The present invention features novel methods and compositions for coating textile substrates, wherein the coating compositions are composed of a coating agent selected from one of (a) an azetidinium polymer, (b) a guanidine polymer, (c) a mixture of an azetidinium polymer and a guanidine polymer, and (d) a copolymer of an azetidinium monomer and a guanidine monomer. Textile substrates coated with the compositions provide high quality printed images when printed with an ink containing a reactive dye having ionizable and/or nucleophilic groups capable of reacting with the coating agent in the textile coating composition. Images printed on a textile substrate coated with a coating composition of the invention are bleed-resistant, water-resistant (e.g., water-fast), detergent-resistant (e.g., detergent-fast), and/or are characterized by an enhanced chroma and hue.

The present invention is directed to treatment of textiles, and more particularly relates to a method and composition for treating textiles to improve the quality of images printed thereon.
Current textile printing technologies are deficient in meeting modem, time-driven, demand-responsive manufacturing strategies. In general, the conventional method of printing on textiles involves crosslinking a colorant to the cellulosic fiber of the textile itself. This approach is limited in that it relies on processes that involve multiple, time-consuming steps. Furthermore, the types of substrates and colorants that can be used are limited.
One approach for increasing textile printing speed involves the use of inkjet printing. Inkjet printers are very popular, due at least in part to their reliability, relatively quiet operation, versatility, graphics capability, print quality, and low cost. Moreover, inkjet printers have made possible xe2x80x9con demandxe2x80x9d color printing without the need for complicated devices. Because inkjet printing has become so popular in both home and commercial use, several water-soluble inks are available. The inks are typically composed of water and a colorant, usually a dye or pigment dispersion, and often contain a number of additives for imparting certain features to the ink, e.g., improved stability and flow, smear resistance, and the like.
Unfortunately, the use of inkjet printing techniques to print on textiles has met with several problems. First, and in spite of the large number of inkjet inks currently available, inkjet printed images on textiles are often of low quality. For example, the printed images often smear upon handling, exhibit bleed (the intrusion of one color into an adjacent color), are moisture sensitive, and are dull, i.e., colored inks when printed fail to accurately produce the expected hues. Moreover, the printed images are often neither water-fast nor detergent-resistant, resulting in fading of the printed image after washing. Printed textile images with these drawbacks are wholly unacceptable to the textile industry, which requires not only that the image be both water-resistant and detergent-resistant, but also that the colors and hues are those deemed acceptable in the textile field. In addition, the textile industry also demands that while the colorant of the ink must adhere tenaciously to the substrate, it also must not alter the desirable hand properties of the substrate. This combination of requirements is very difficult to accomplish.
Although there have been developments and improvements in the field of textile printing, the methods currently used still do not provide optimum results. Thus, there is a need in the art for a textile treatment that can overcome the above problems, is relatively inexpensive, and can generally provide a high quality inkjet printed image on a textile substrate, preferably using presently available dyes. The present invention is addressed to this need.
The present invention features a novel method and composition for coating textile substrates, wherein the composition is composed of a coating agent selected from one of (a) an azetidinium polymer, (b) a guanidine polymer, (c) a mixture of an azetidinium polymer and a guanidine polymer, and (d) a copolymer of an azetidinium monomer and a guanidine monomer. When applied to a textile substrate, the coating composition provides a coated textile substrate that yields high quality printed images when printed with an ink containing a reactive dye having ionizable and/or nucleophilic groups capable of reacting with the coating agent. Images printed on a textile substrate coated with the coating composition of the invention are bleed-resistant, water-resistant (e.g., water-fast), detergent-resistant (e.g., detergent-fast), and/or are characterized by an enhanced chroma and hue.
It is a primary object of the invention to address the above-mentioned need in the art by providing a coating composition that can be readily applied to a variety of textile substrates and that efficiently binds colorant upon printing, thus providing an economical, efficient means for processing textiles so as to facilitate production of a high quality printed image.
Another object of the invention is to provide a printed textile substrate that is of high quality (particularly with respect to optical density and brightness of the printed image), and that is bleed-resistant, water-resistant (e.g., water-fast), and detergent-resistant (e.g., detergent-fast).
Still another object of the invention is to provide a method for coating textiles using the coating compositions of the invention.
Still an additional object of the invention is to provide a method for printing on a coated textile substrate to provide water-resistant (e.g., water-fast) and/or detergent-resistant (e.g., detergent-fast) images thereon.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention.
Definitions and Nomenclature
It must be noted that, as used in the specification and the appended claims, the singular forms xe2x80x9ca,xe2x80x9d xe2x80x9canxe2x80x9d and xe2x80x9cthexe2x80x9d include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to xe2x80x9ca colorant-reactive componentxe2x80x9d in a composition means that more than one colorant-reactive component can be present in the composition, reference to xe2x80x9ca colorantxe2x80x9d in a composition means that more than one colorant can be present in the composition, reference to xe2x80x9ca polymerxe2x80x9d includes combinations of different polymers, and the like.
xe2x80x9cTextilexe2x80x9d or xe2x80x9ctextile substratexe2x80x9d as used herein refers to any cellulose-based or non-cellulose based textile material suitable for use as a printing substrate in connection with the coatings and/or methods of the invention. In general, where appropriate, the textile substrate has been sized, internally and/or externally, prior to application of the compositions of the invention.
The terms xe2x80x9ctreated textile substrate,xe2x80x9d xe2x80x9ccoated textile substrate,xe2x80x9d xe2x80x9ctreated textile substrate,xe2x80x9d and xe2x80x9ccoated textile substratexe2x80x9d are generally used herein to refer to a textile substrate that is treated with, i.e., has applied to its surface and/or is partially or wholly saturated with, a coating of the present invention, to provide for improved printing performance, particularly with respect to water resistance (e.g., water-fastness), detergent resistance (e.g., detergent-fastness), brightness, and the like. The coating may be applied as a pretreatment, i.e., prior to printing, simultaneously with printing, or as an after-treatment. Preferably, the coating is applied to the substrate in a separate coating operation prior to printing, typically in amounts ranging from fifty (50) to five hundred (500) pounds per ton of substrate.
xe2x80x9cCoating compositionxe2x80x9d as used herein is generally meant to refer to a composition of the invention comprised of a coating agent as described herein. The coating composition may contain components in addition to the coating agents described herein, such as binders, colorants, etc. The use of the term xe2x80x9ccoatingxe2x80x9d in the phrase xe2x80x9ccoating compositionxe2x80x9d is not limited to the presence of the composition on a surface of a textile substrate, but is also intended to encompass a textile substrate that has been infiltrated with the composition, such that the composition is present within the fibers of the treated substrate. Unless specifically indicated otherwise, xe2x80x9ccoatingxe2x80x9d in reference to the coating compositions and coating agents of the invention is used only as a term of convenience, and is not meant to be limiting as to the manner of application of the compositions of the invention, or their final location on and/or within a treated textile substrate.
xe2x80x9cAqueous based inkxe2x80x9d refers to an ink composed of an aqueous carrier medium and a colorant, such as a dye or a pigment dispersion. An aqueous carrier medium is composed of water or a mixture of water and one or more water-soluble organic solvents. Exemplary aqueous based ink compositions are described in detail below.
xe2x80x9cColorantxe2x80x9d as used herein is meant to encompass dyes, pigments, stains, and the like compatible for use with the coating agents and compositions of the invention.
The term xe2x80x9ccolorant-reactive componentxe2x80x9d as used herein refers to a component (e.g., a chemical moiety) of a coating agent of the invention that is capable of reacting with a selected colorant, particularly a colorant having a nucleophilic and/or ionizable group, to form a coating agent-colorant complex. The coating agent-colorant complex is formed through either a covalent, electrostatic, or ionic association between the colorant-reactive coating agent and the colorant. When a coating agent having a colorant-reactive component and a selected colorant form a coating agent-colorant complex in the context of a printed image on a textile substrate, the association between the colorant and the color-reactive component of the coating agent is effective to impart advantageous qualities to the printed image on the textile substrate, particularly with respect to water resistance, detergent resistance, enhanced optical density, enhanced brightness, and the like.
The term xe2x80x9corganic solventxe2x80x9d is used herein in its conventional sense to refer to a liquid organic compound, typically a monomeric organic material in the form of a liquid, preferably a relatively nonviscous liquid, the molecular structure of which contains hydrogen atoms, carbon atoms, and optionally other atoms as well, and which is capable of dissolving solids, gases or liquids.
The term xe2x80x9csignificantxe2x80x9d, as when used with reference to xe2x80x9csignificantly enhanced brightnessxe2x80x9d or xe2x80x9csignificantly improved water resistancexe2x80x9d generally refers to a difference in a quantifiable, measurable, or otherwise detectable parameter, e.g., optical density, LAB graphs (color sphere), dot spread, bleed through, between the two groups being compared (e.g., untreated versus treated textile substrates) that is statistically significant using standard statistical tests. For example, the degree of visual wicking or water resistance in a treated textile substrate as detected in a print assay may be quantified using standard methods, and the degree of wicking or water resistance under different conditions can be compared for both treated and untreated textile substrates to detect statistically significant differences.
The term xe2x80x9cfluid resistancexe2x80x9d is used herein to describe the resistance of a textile substrate to penetration by a fluid, with the term xe2x80x9cwater resistancexe2x80x9d specifically referring to resistance of a textile substrate to penetration by a fluid.
The term xe2x80x9cwater-fastxe2x80x9d is used herein to describe a form of water resistance, and is normally used to refer to the nature of the ink composition after drying on a substrate. In general, xe2x80x9cwater-fastxe2x80x9d means that the dried composition is substantially insoluble in water, such that upon contact with water, the dried ink retains at least about 70%, preferably at least about 85%, and more preferably at least about 95%, of optical density.
The term xe2x80x9cdetergent-resistantxe2x80x9d is used herein to describe the nature of the ink composition after exposure to detergent (e.g., during washing). xe2x80x9cDetergent-fastxe2x80x9d is intended to refer to a particular high-level of xe2x80x9cdetergent resistance,xe2x80x9d and is generally used to mean that the dried composition is substantially insoluble in water, such that upon contact with water, the dried ink retains at least about 70%, preferably at least about 85%, and more preferably at least about 95%, of optical density.
The term xe2x80x9cbleed resistancexe2x80x9d is meant to refer to the retardation of the penetration of water into a textile substrate, which retardation is associated with creation of a low energy hydrophobic surface at the textile fiber-water interface which increases the contact angle formed between a drop of liquid and the surface, and thus decreases the wettability. Contact angles have been shown to be sensitive to molecular packing, surface morphology, and chemical constitution of the textile substrate and any components added thereto.
The term xe2x80x9crub resistancexe2x80x9d is normally meant to refer to a characteristic of the ink composition after drying on a substrate, more specifically, the ability of a printed image to remain associated with the substrate upon which it is printed despite application of force (e.g., rubbing) to the printed image. In general, xe2x80x9crub-resistantxe2x80x9d means that the dried ink composition is substantially resistant to rubbing force so that the dried ink retains at least about 70%, preferably at least about 85%, and more preferably at least about 95%, of optical density after rubbing of the printed image.
The term xe2x80x9calkylxe2x80x9d as used herein refers to a branched or unbranched saturated hydrocarbon group of 1 to 24 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl, tetradecyl, hexadecyl, eicosyl, tetracosyl and the like, as well as cycloalkyl groups such as cyclopentyl, cyclohexyl and the like. The term xe2x80x9clower alkylxe2x80x9d intends an alkyl group of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms.
The term xe2x80x9calkylenexe2x80x9d as used herein refers to a difunctional, branched or unbranched saturated hydrocarbon group of 1 to 24 carbon atoms, including without limitation methylene, ethylene, ethane-1,1-diyl, propane-2,2-diyl, propane-1,3-diyl, butane-1,3-diyl, and the like. xe2x80x9cLower alkylenexe2x80x9d refers to an alkylene group of 1 to 6 carbon atoms.
The term xe2x80x9calkoxyxe2x80x9d as used herein intends an alkyl group bound through a single, terminal ether linkage; that is, an xe2x80x9calkoxyxe2x80x9d group may be defined as xe2x80x94OR where R is alkyl as defined above. A xe2x80x9clower alkoxyxe2x80x9d group intends an alkoxy group containing 1 to 6 carbon atoms.
xe2x80x9cHaloxe2x80x9d or xe2x80x9chalogenxe2x80x9d refers to fluoro, chloro, bromo or iodo, and usually relates to halo substitution for a hydrogen atom in an organic compound.
The term xe2x80x9cpolymerxe2x80x9d is used herein in its conventional sense to refer to a compound having two or more monomer units, and is intended to include homopolymers as well as copolymers. The term xe2x80x9cmonomerxe2x80x9d is used herein to refer to compounds which are not polymeric.
xe2x80x9cOptionallyxe2x80x9d or xe2x80x9coptionallyxe2x80x9d means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. For example, the phrase xe2x80x9coptionally substitutedxe2x80x9d aromatic ring means that the aromatic ring may or may not be substituted and that the description includes both an unsubstituted aromatic ring and an aromatic ring bearing one or more substituents.
Overview of the Invention
The present invention is based upon the discovery that a coating composition containing a coating agent that is (a) an azetidinium polymer, (b) a guanidine polymer, (c) a mixture of an azetidinium polymer and a guanidine polymer, or (d) a copolymer of an azetidinium monomer and a guanidine monomer, can be used to treat a textile substrate to significantly improve the quality of images printed thereon. Textile substrate that has been treated with a coating agent of the invention can provide high quality printed images having improved color fastness, that is, the printed images do not run when exposed to moisture and/or detergent, as a result of the substantially non-reversible binding of aqueous colorants to the image-enhancing agent present in the image-enhancing composition. These images are therefore characterized as xe2x80x9cwater-resistantxe2x80x9d (e.g., water-fast) and/or detergent-resistant (e.g., detergent-fast) due to the characteristics of the printed image following exposure to water and/or detergent.
The coated textile substrates of the invention can be used with conventional textile printing processes, or may be used with digital printing techniques such as inkjet printing (including drop-on-demand printing and continuous printing), to provide highly brilliant, printed images that are significantly improved in color quality, for example, with respect to chroma and hue. The coating agents and compositions of the invention thus provide a number of advantages over conventional textile printing methods.
The coating agents, compositions, methods of treating textile substrates using the compositions described herein, and other features of the invention are described in greater detail below.
Coating Compositions
In general, the coating composition of the invention is composed of a coating agent selected from the group consisting of (a) an azetidinium polymer, (b) a guanidine polymer, (c) a mixture of an azetidinium polymer and a guanidine polymer, and (d) a copolymer of an azetidinium monomer and a guanidine monomer. In general, the coating agents have a colorant-reactive component, which is capable of reacting with a selected colorant, particularly a colorant having a nucleophilic and/or ionizable group, to form a coating agent-colorant complex through a covalent, electrostatic, or ionic association. The association of the coating agent and colorant imparts bleed resistance, water resistance (e.g., water-fastness), detergent resistance (e.g., detergent-fastness), and other desirable characteristics to the printed, treated textile substrate. In addition to the coating agent, the coating compositions can include components such as film-forming binders, pigments, and other additives.
In general, the compositions can be readily prepared from commercially available starting materials and/or reagents, are compatible with additional binders or additives, can be used with a variety of base textile substrates, are compatible with a variety of printing methods, including conventional textile printing as well as digital printing methods (particularly inkjet printing, including drop-on-demand and continuous printing), and can also be used with existing commercial textile coating processes and equipment. The coating compositions are inexpensive to prepare, and relatively small amounts are required to provide a coated textile substrate having the advantageous features described herein. The coating compositions are also easy to handle due to their solubility in water (the active coating agents are hydrophilic polymers), and do not require the use of large volumes of organic solvents. The coating compositions also possesses good film-forming properties.
The treated textile substrates prepared using the coating compositions of the invention exhibit improved stability upon prolonged storage, and in some instances, improved durability, as evidenced by improved strength, e.g., tear strength. The treated textile substrate does not discolor or yellow, and maintains a high degree of brightness for extended periods of time. Textile substrates treated with the coating compositions of the invention react rapidly with a number of aqueous based colorants, thus providing a versatile coating system for use with a wide variety of available colorants. Furthermore, because the colorant reacts quickly with the coating compositions, the printed substrate does not require a separate curing step, but rather is fast-drying. This fast-drying characteristic provides for printed images that are xe2x80x9cnon-sticky,xe2x80x9d thus allowing the printed textile substrate to be handled immediately after printing, for example, to allow stacking. The treated textile substrate of the invention can also be used to prepare images with varying degrees of gloss, depending upon variations in pigment.
In addition to their water resistance, textile substrates treated with a coating composition of the invention are highly bleed-resistant (as evidenced by small dot size measurements, i.e., less wicking action), detergent-resistant and rub-resistant.
The various components of the coating compositions of the invention will now be described.
Coating Agents
Coating agents in the coating compositions of the invention generally comprise an azetidinium polymer, a guanidine polymer, a copolymer of an azetidinium monomer and a guanidine monomer, or a mixture of an azetidinium polymer and a guanidine polymer. In general, the coating agent represents approximately 1 wt. % to 100 wt. %, typically 50 wt. % to 95 wt. %, preferably 70 wt. % to 95 wt. % of the coating composition after drying on a substrate.
(A) Azetidinium Polymers
In one embodiment, the coating agent is an azetidinium polymer. An xe2x80x9cazetidinium polymerxe2x80x9d is a polymer comprised of monomeric subunits containing a substituted or unsubstituted azetedine ring (i.e., a four membered nitrogen-containing heterocycle). In general, the azetidinium polymers useful herein are composed of monomer units having the structural formula (I):
in which R1 and R2 are independently lower alkylene, Xxe2x88x92 is an anionic, organic or inorganic counterion, and Y1, Y2 and Y3 are selected from the group consisting of hydrogen, hydroxyl, halo, alkoxy, alkyl, amino, carboxy, acetoxy, cyano and sulfhydryl. Preferred such polymers are wherein R1 and R2 are methylene, Xxe2x88x92 is selected from the group consisting of halide, acetate, methane sulfonate, succinate, citrate, malonate, fumarate, oxalate and hydrogen sulfate, Y1 and Y3 are independently hydrogen or lower alkyl, and Y2 is hydrogen or hydroxyl. In particularly preferred azetidinium polymers herein, Y1 and Y3 are hydrogen and Y2 is hydroxyl.
The azetidinium polymer may be a homopolymer, or it may be a copolymer, wherein one or more non-azetidinium monomer units are incorporated into the polymer structure. Any number of comonomers may be employed to form suitable azetidinium copolymers for use herein; however, a particularly preferred azetidinium copolymer is aminoamide azetidinium. Further, the azetidinium polymer may be essentially straight-chain or it may be branched or crosslinked.
Azetidinium polymers can associate with colorant in two different ways. First, the azetidinium polymer can associate with colorant through an ionic interaction, where the colorant provides anionic groups, such as carboxy or sulfonate, that can ion-exchange with the polymer counterions (Xxe2x88x92 in Formula (I), above), thus fixing the colorant to the textile substrate via an electrostatic-type interaction. Second, nucleophilic groups present within the colorant can react with the azetidinium groups of the polymer via a ring-opening reaction. A characteristic ring-opening reaction of an azetidinium polymer of the invention may be illustrated as follows:
The colorant (◯-Nucxe2x88x92) thus covalently bonds to the coating agent, to form a cross-linked coating agent-colorant complex. Colorant thus applied to a coated textile substrate is rapidly and irreversibly bound to the textile substrate.
The percentage of reactive azetidinium groups in the polymer can be adjusted in a controlled manner to tailor the number of reactive groups in the polymer. Azetidinium groups are insensitive to pH change; however, such groups are highly sensitive to the presence of anionic and nucleophilic species. In some cases, it may be desirable to adjust the reaction conditions used to prepare the azetidinium polymer (e.g., by raising the pH) to generate anionic groups within the polymer, which then participate in intramolecular crosslinking.
A preferred azetidinium polymer for use in the present invention is shown in Formula (II)
Commercially available such polymers include xe2x80x9cAMRES(copyright),xe2x80x9d available from Georgia Pacific Resins, Inc., Atlanta, Ga., xe2x80x9cKYMENE(copyright),xe2x80x9d from Hercules, Inc., Wilmington, Del., and xe2x80x9cPolycup(copyright),xe2x80x9d also from Hercules, Inc. These azetidinium polymers are generally referred to as poly(aminoamide)-epichlorohydrin (PAE) resins; such resins are typically prepared by alkylating a water-soluble polyamide containing secondary amino groups with epichlorohydrin. Other suitable azetidinium polymers will be known to those skilled in the art and/or are described in the pertinent texts, patent documents, and literature references; see, for example, Moyer, et al., in WET STRENGTH IN PAPER AND PAPERBOARD, Tappi Monograph Series No. 29, Tappi Press, Ch. 3, p. 33-37 (1965); Chan, in TAPPI WET AND DRY STRENGTH SHORT COURSE, Tappi Press, Atlanta, Apr. 13-15, 1988; and Espy, in WET STRENGTH RESINS AND THEIR APPLICATION, Ed., Lock L. Chan, Tappi Press, Atlanta, Ga. (1994).
(B) Guanadine Polymers
In another embodiment, the coating agent is a guanidine polymer, also termed a xe2x80x9cpolyguanidine.xe2x80x9d The guanidino group is extremely basic, possessing a pKa of about 12-13. Polyguanidines for use in the invention are typically provided as acid salts wherein the imine nitrogen atoms are for the most part in protonated form.
In general, guanidine polymers useful as coating agents in the present invention are either homopolymers or copolymers. All guanidine polymers herein are comprised of recurring monomer units having the structural formula
wherein R3 is hydrogen or lower alkyl and R4 is hydrogen, alkyl, alkoxy, or hydroxyl-substituted alkoxy. Preferably, R3 and R4 are hydrogen. Particularly preferred guanidine polymers for use herein are comprised of monomer units having the structural formula (IV)
wherein n is an integer in the range of 1 to 10 inclusive, R3 is hydrogen or lower alkyl and R4 is hydrogen, alkyl, alkoxy, or hydroxyl-substituted alkoxy. Preferably, R3 and R4 are hydrogen.
A particularly preferred guanidine polymer for use in the methods and compositions of the invention has the structure of formula (IV) wherein R3 and R4 are H and n is 6 (3,12-diimino-2,4,11,13-tetraazatetradecanediimidamide), available under the tradenames xe2x80x9cBAQUACIL(copyright)xe2x80x9d and xe2x80x9cVANTOCIL(copyright),xe2x80x9d from Zeneca, Inc.
Polyguanidine polymers of the invention react electrostatically with anionic groups present in the dye via ion-exchange type interactions, to rapidly and irreversibly bind anionic type dyes to print textile substrates coated with such polymers.
(C) Mixtures of Azetidinium Polymers and Guanidine Polymers
In another embodiment, the coating agent comprises a mixture of an azetidinium polymer and a guanidine polymer. The two polymers may be present in any suitable ratio relative to one another. The relative amounts of polyguanidine and polyazetidinium can range from about 0.05% polyguanidine/99.95% polyazetidinium to 0.05% polyazetidinium/99.95% polyguanidine. The actual relative amounts of polyguanidine and polyazetidinium will vary according to the composition of the ink to be used (e.g., the nature of the colorant in the ink), the nature of the textile substrate, and other factors affecting the use of the polymers, such as the relative market price for each polymer. In general, it is preferable to use a smaller amount of guanidine relative to azetidinium.
In this embodiment, it is important that the pH of the coating composition be acidic, as the composition tends to gel at basic pH. If necessary, then, an acid should be added to the coating composition to ensure that the pH is below 7.0, preferably less than about 5.5, and most preferably in the range of about 1.0 to 5.5. Suitable acids include sulfuric acid, hydrochloric acid, acetic acid, and the like.
Although it will be appreciated that any of a number of azetidinium or guanidine polymers can be used to prepare the coating compositions and coated textile substrates described herein, a preferred polymer is a poly (aminoamide)-azetidinium polymer, e.g., a polyazetidinium chloride-based polymer, such as a polyamide-polyamine-epichlorohydrin resin.
(D) Copolymers of Azetidinium Monomers and Guanidine Monomers
In another embodiment, the coating agent is a copolymer of an azetidinium monomer unit and a guanidine monomer unit. In general, the azetidinium monomer unit has the structural formula (I)
in which R1 and R2 are independently lower alkylene, Xxe2x88x92 is an anionic, organic or inorganic counterion, and Y1, Y2 and Y3 are selected from the group consisting of hydrogen, hydroxyl, halo, alkoxy, alkyl, amino, carboxy, acetoxy, cyano and sulfhydryl. Preferred monomers are wherein R1 and R2 are methylene, Xxe2x88x92 is selected from the group consisting of halide, acetate, methane sulfonate, succinate, citrate, malonate, fumarate, oxalate and hydrogen sulfate, Y1 and Y3 are independently hydrogen or lower alkyl, and Y2 is hydrogen or hydroxyl. In particularly preferred azetidinium monomers, Y1 and Y3 are hydrogen and Y2 is hydroxyl. The guanidine monomer has the structural formula (III)
or the structural formula (IV)
wherein R3, R4 and n are as defined earlier herein.
The ratio of azetidinium monomers to guanidine monomers in the copolymer, as well as the distribution of each monomer type in the copolymer, can be varied according to a number of factors, and may be, for example, tailored for use with specific colorants having certain types of ionic and/or nucleophilic groups. The precise composition of the copolymer may also be varied to best accommodate the nature of the textile substrate to be coated.
Film-Forming Binders
The textile coating compositions of the invention preferably include a film-forming binder. By xe2x80x9cfilm-forming binderxe2x80x9d is meant a substance that provides for improved strength of a textile substrate upon application of the substance to the substrate. xe2x80x9cFilm-forming bindersxe2x80x9d used in connection with the coating compositions of the invention include any film-forming binder that is compatible with the coating agent and other components of the composition. Exemplary film-forming binders include, but are not necessarily limited to: polysaccharides and derivatives thereof, e.g., starches, cellulosic polymers, dextran and the like; polypeptides (e.g., collagen and gelatin); and synthetic polymers, particularly synthetic vinyl polymers such as poly(vinyl alcohol), poly(vinyl phosphate), poly(vinyl pyrrolidone), vinyl-pyrrolidone-vinyl acetate copolymers, vinyl alcohol-vinyl acetate copolymers, vinyl pyrrolidone-styrene copolymers, and poly(vinylamine), and cationic film-forming binders such as quaternized vinyl pyrrolidone-dimethylaminoethyl-methacrylate copolymer, dimethylaminoethyl-methacrylate-co-methyl methacrylate, polydiallyldimethyl ammonium chloride and quaternized aminoacrylate polymers. The coating agents herein are themselves film-forming substances; however, it is generally desirable to use these coating agents with additional film-forming substances.
Polysaccharide binders: Starches, as noted above, represent one category of suitable film-forming binders for use herein. Suitable starches may be any of a variety of natural, converted, and synthetically modified starches. Exemplary starches include, but are not necessarily limited to starch (e.g., SLS-280 (St. Lawrence Starch)), cationic starches (e.g., Cato-72 (National Starch), hydroxyalkylstarch, wherein the alkyl has at least one carbon atom and wherein the number of carbon atoms is such that the material is water soluble, preferably from about 1 to about 10 carbon atoms, such as methyl, ethyl, propyl, butyl, or the like (e.g., hydroxypropyl starch #02382 (PolySciences, Inc.), hydroxyethyl starch #06733 (PolySciences, Inc.), Penford Gum 270 and 280 (Penford), and Film-Kote (National Starch)), starch blends (see, e.g., U.S. Pat. No. 4,872,951, describing a blend of cationic starch and starch treated with an alkyl or alkenyl succinic anhydride (ASA), preferably 1-octenyl succinic anhydride (OSA)), and the like. The film-forming binder can also be a synthetically produced polysaccharide, such as a cationic polysaccharide esterified by a dicarboxylic acid anhydride (see, e.g., U.S. Pat. No. 5,647,898). Additional saccharide binders include cellulosic materials such as alkyl celluloses, aryl celluloses, hydroxy alkyl celluloses, alkyl hydroxy alkyl celluloses, hydroxy alkyl celluloses, dihydroxyalkyl cellulose, dihydroxyalkyl cellulose, hydroxy alkyl hydroxy alkyl cellulose, halodeoxycellulose, amino deoxycellulose, dialkylammonium halide hydroxy alkyl cellulose, hydroxyalkyl trialkyl ammonium halide hydroxyalkyl cellulose, dialkyl amino alkyl cellulose, carboxy alkyl cellulose salts, cellulose sulfate salts, carboxyalkylhydroxyalkyl cellulose and the like). Still additional film-forming binders of this type include dextran (e.g., dialkyl aminoalkyl dextran, amino dextran, and the like), carrageenan, Karaya gum, xanthan, guar and guar derivatives, (e.g., carboxyalkyl hydroxyalkyl guar, cationic guar, and the like), and gelatin.
Additional exemplary film-forming binders include resins (e.g., such as formaldehyde resins such as melamine-formaldehyde resin, urea-formaldehyde resin, alkylated urea-formaldehyde resin, and the like), acrylamide-containing polymers (e.g., poly(acrylamide), poly(N,N-dimethylacrylamide), and the like), poly(alkyleneimine)-containing polymers (e.g., poly(ethyleneimine), poly(ethyleneimine) epichlorohydrin, alkoxylated poly(ethyleneimine), and the like), polyoxyalkylene polymers (e.g., poly(oxymethylene), poly(oxyethylene), ethylene oxide/propylene oxide copolymers, ethylene oxide/2-hydroxyethyl methacrylate/ethylene oxide and ethylene oxide/hydroxypropyl methacrylate/ethyleneoxide triblock copolymers, ethylene oxide-4-vinyl pyridine/ethylene oxide triblock copolymers, ethylene oxide-isoprene/ethylene oxide triblock copolymers, epichlorohydrin-ethylene oxide copolymer, and the like), etc.
Any of the above exemplary film-forming binders can be used in any effective relative amounts, although typically the film-forming binder, if present, represents approximately 1 wt. % to 40 wt. %, preferably 1 wt. % to 25 wt. %, most preferably 1 wt. % to 15 wt. % of the composition, after drying on a textile substrate.
Other Components of the Textile Coating Composition
Additional coating composition components may include, but are not necessarily limited to, inorganic fillers, anti-curl agents, or additional conventional components such as a surfactant, plasticizer, humectant, UV absorber, light fastness enhancer, polymeric dispersant, dye mordant, optical brightener, fabric softener or leveling agent, as are commonly known in the art. Preferred additives are optical brighteners and fabric softeners, each of which generally represents approximately 0.5 wt. % to 2.0 wt. % of the coating composition after drying on a substrate. Illustrative examples of such additives are provided in U.S. Pat. Nos. 5,279,885 and 5,537,137. The coating compositions may also include a crosslinking agent, such as zirconium acetate, ammonium zirconium carbonate, or the like, for intramolecular and/or intermolecular crosslinking of coating agent(s) in the coating composition and/or a chelating agent such as boric acid. Additional components that may be desirable for use in the textile coating compositions of the invention will be known to those skilled in the art and/or described in the pertinent texts and literature.
The coating composition is preferably provided in an aqueous liquid vehicle, although small amounts of a water-soluble organic solvent may be present. The aqueous liquid vehicle will generally be water, although other nonorganic compounds that are either water soluble or water miscible may be included as well. It may on occasion be necessary to add a solubilizing compound during preparation of the coating composition so that the components dissolve in the aqueous liquid vehicle, e.g., an inorganic base such as ammonia and/or an organic amine. Suitable organic amines include lower alkyl-substituted amines such as methylamine, dimethylamine, ethylamine, and trimethylamine, as well as ethanolamine, diethanolamine, triethanolamine, and substituted ethanolamines, typically lower alkyl-substituted ethanolamines such as N-methyl and N,N-dimethyl ethanolamines, and morpholine. Such compounds are also useful for bringing the pH into the desired range for basic formulations, and, if present, will generally represent not more than about 20 wt. % of the composition, and in most cases will represent not more than about 10 wt. % of the composition.
Textile Substrates
In general, the textile coating compositions and printing methods of the invention can be used with any textile substrate amenable to use with such coating compositions and methods. Suitable textile substrates for use with the present invention include textiles having natural, synthetic, cellulose-based, or non-cellulose-based fibers or any combination thereof. Exemplary textile substrates include, but are not limited to, textiles having hydroxy group-containing fibers such as natural or regenerated cellulosic fibers (cotton, rayon, and the like); nitrogen group-containing fibers such as polyacrylonitrile; natural or synthetic polyamides (including wool, silk, or nylon); and/or fibers having acid-modified polyester and polyamide groups. The substrates may be additionally pre-treated or after-treated with resins or other substances compatible with the coating compositions and methods of the invention, and may be finished or unfinished. The textile substrate may also be sized prior to application of the present coating compositions. Alternatively, the present coating compositions may be incorporated into an external sizing process, so that sizing and coating is conducted in a single step.
The fibers of the textile substrate may be in any suitable form compatible with the selected printing process. e.g., loose yams, or fabrics. Fabrics are a convenient and preferred form. The fibers may be blended with other fibers that are susceptible to treatment with a coating composition of the invention, or with fibers that may prove less susceptible to such treatment. The process may also be used with leather, vinyl and other natural or synthetic materials. Additional exemplary substrates for use in the invention include polyester films such as xe2x80x9cMYLARxe2x80x9d flexible film, polysulfones, cellulose triacetates, and the like. Coated transparent films are also contemplated.
Application of the Coating Compositions to Textile Substrates
Coated textile substrates, also referred to herein as xe2x80x9ctreated textile substrates,xe2x80x9d can be prepared by any of a number of conventional coating processes commonly employed in the art. In general, the coating composition is applied to the textile substrate to provide a treated textile substrate in a manner that leaves the coating agent physically and chemically accessible to inks for reaction of the colorant-reactive coating agent within the colorant contained in the ink. The term xe2x80x9ccoatingxe2x80x9d as used herein encompasses both a surface coating as well as a coating that has infiltrated the textile to some degree, so long as, in the latter case, the coating agent is still accessible to colorant for printing.
The textile coating composition is applied to a textile substrate to achieve a desired coating layer thickness and/or to achieve delivery of a desired amount of coating composition to the textile substrate. The amount of coating composition used will vary with a number of factors, including, for example, the absorptive nature of the substrate, the ink to be used in printing on the substrate, the printing application to be used, and the like. In general, the coating composition is applied in an amount that results in a coating representing approximately 0.5 wt. % to 20 wt. % of the textile substrate after drying.
The coating is applied to at least one surface of the textile substrate, and may be applied to both a top and bottom surface of the substrate to facilitate printing on opposing substrate surfaces. The coating composition may also be applied by saturating a textile substrate. As will be appreciated by those skilled in the art, the coating compositions of the invention are applied by any suitable means, which may include continuous processes, application as a continuous film, padding, dipping, spraying, foam application, exhaust processes, or by using a rod, roll, flexopress, blade, or air-knife coater.
The coating composition may be applied to the textile substrate as a pretreatment, simultaneously with printing, or as an after-treatment. Preferably, the coating composition is applied to the substrate as a pretreatment, i.e., prior to printing.
The coated textile substrate described herein possesses advantageous features. For example, the coated textile substrate does not discolor or yellow. Additionally, the coating composition is compatible with a variety of textiles. Moreover, textile substrates coated with the coating compositions described herein react rapidly with applied aqueous colorants.
Preparation of Printed Images on Treated Textile Substrates:
The coated textile substrates of the invention can be printed on using any suitable inks and any suitable printing method, e.g., conventional methods of printing, digital printing (e.g., inkjet printing, including drop on-demand and continuous jet printing), and the like.
In general, aqueous inks are used in the preparation of a printed image on the treated textile substrates of the invention. Aqueous inks for use in preparing a printed image may be any suitable ink having a colorant, e.g., a pigment, dye, or stain, having one or more reactive groups suitable for reacting, either covalently or ionically, with a colorant-reactive component of a coating agent in the coating of the treated textile substrate. The selection of the specific ink and colorant will vary with colorant-reactive component of the coating agent. For example, when the colorant-reactive component is an azetidinium group, the colorant has an anionic or nucleophilic group for reaction with the azetidinium group. When the colorant-reactive component is a guanidino group, the colorant has an anionic group for reaction with the guanidino group. Thus, preferred colorants for use in printing on a textile substrate coated with an azetidinium-containing coating composition are those containing one or more nucleophiles, e.g., having an amino, carboxy, sulfonato, thiosulfonato, cyano, hydroxy or sulfido group or the like. Preferred colorants for use in printing a treated textile substrate coated with a polyguanidine-containing coating composition are those containing an anionic group, e.g., having a carboxy, sulfonato, thiosulfonato, cyano, halo, or phosphonato group or the like.
The inks used in conjunction with the textile coating compositions of the invention may be inkjet inks. Water-soluble colorants in the inkjet inks may be acid dyes, direct dyes, basic dyes or dispersive dyes; preferred dyes are described in U.S. Pat. Nos. 5,425,805, 5,537,137, and 5,441,561.
The selection of the aqueous based ink will depend upon the requirements of the specific application, such as desired surface tension, viscosity, drying time, the type of textile substrate upon which the ink is to be applied (printing medium), and the like. The aqueous liquid vehicle of inks suitable for use in the invention will generally be water, although other nonorganic compounds which are either water soluble or water miscible may be included as well. The colorant may be dissolved, dispersed or suspended in the aqueous liquid vehicle, and is present in an amount effective to provide the dried ink with the desired color and color intensity.
In some instances, the dye is contained in a carrier medium composed of ink and a water soluble organic solvent. For applications utilizing such a carrier medium, representative solvents include polyhydridic alcohols such as polyethylene alcohol, diethylene glycol, propylene glycol, and the like. Additional solvents are simple alcohols such as ethanol, isopropanol and benzyl alcohol, and glycol ethers, e.g., ethylene glycol monomethyl ether, diethylene glycol monoethyl ether. Representative examples of water soluble organic solvents are described in U.S. Pat. Nos. 5,085,698 and 5,441,561.
Preferred colorants contained in the inks useful with the invention are dyes, including azo or xe2x80x9cdirectxe2x80x9d dyes as well as dyes containing acidic groups (e.g., carboxylate, phosphonate or sulfonate moieties), basic groups (e.g., unsubstituted amines or amines substituted with 1 or 2 alkyl, typically lower alkyl, groups), or both. Specific examples of suitable colorants include, but are not limited to, the following: Dispersol Blue Grains (Zeneca, Inc.), Duasyn Acid Blue (Hoechst Celanese), Duasyn Direct Turquoise Blue (Hoechst Celanese), Phthalocyanine blue (C.I. 74160), Diane blue (C.I. 21180), Pro-jet Cyan 1 (Zeneca, Inc.), Pro-jet Fast Cyan 2 (Zeneca, Inc.), Milori blue (an inorganic pigment equivalent to ultramarine) as cyan colorants; Dispersol Red D-B Grains (Zeneca, Inc.), Brilliant carmine 6B (C.I. 15850), Pro-jet magenta 1 (Zeneca, Inc.), Pro-jet Fast magenta 2 (Zeneca, Inc.), Brilliant Red F3B-SF (Hoechst Celanese), Red 3B-SF (Hoechst Celanese), Acid Rhodamine (Hoechst Celanese), Quinacridone magenta (C.I. Pigment Red 122) and Thioindigo magenta (C.I. 73310) as magenta colorants; Dispersol Yellow D-7G 200 Grains (Zeneca, Inc.), Brilliant yellow (Hoechst Celanese), Pro-jet yellow 1 (Zeneca, Inc.), Pro-jet Fast Yellow 2 (Zeneca, Inc.), benzidine yellow (C.I. 21090 and C.I. 21100) and Hansa Yellow (C.I. 11680) as yellow colorants; organic dyes; and black materials such as carbon black, charcoal and other forms of finely divided carbon, iron oxide, zinc oxide, titanium dioxide, and the like. Specific and preferred black colorants include Acid Black 48 (Aldrich), Direct Black 58756 A (Crompton and Knowles), BPI Molecular Catalytic Gray (Brain Power), Fasday Cool Gray (Hunter Delator), Dispersol Navy XF Grains (Zeneca, Inc.), Dispersol Black CR-N Grains (Zeneca, Inc.), Dispersol Black XF Grains (Zeneca, Inc.), Disperse Black (BASF), Color Black FW18 (Degussa), Color Black FW200 (Degussa), Hostafine Black TS (Hoechst Celanese), Hostafine Black T (Hoechst Celanese), Duasyn Direct Black (Hoechst Celanese), Pro-jet Black 1 (Zeneca, Inc.) and Pro-jet Fast Black 2 (Zeneca, Inc.).
Printed Textiles
The invention also features a printed, treated textile substrate produced using the methods and compositions described herein. The treated textile substrates of the invention can be printed using any suitable printing method, e.g., conventional methods of printing, digital printing, particularly inkjet printing, including drop on-demand printing and continuous jet printing, and the like. In one embodiment of particular interest, the treated textile substrates are printed by an inkjet printing method. In general, the printing process involves applying an aqueous recording liquid to a treated textile substrate in an imagewise pattern. Inkjet printing processes are well known in the art; see, e.g., U.S. Pat. Nos. 4,601,777; 4,251,824; 4,410,899; 4,412,224; and 4,532,530.
The compositions of the invention make it possible to print the treated textile substrates of the invention using printing methods that are conventionally used in connection with cellulosic paper substrates. For example, printing and/or copying process using dry or liquid electrophotographic-type developers, such as electrophotographic processes, ionographic process, and the like, may be adapted for printing the treated textile substrates of the invention. The treated textile substrates of the invention can also be printed on using a process for generating images that involves generating an electrostatic latent image on an imaging member in an imaging apparatus, developing the latent image with a toner, and transferring the developed image to a treated textile substrate of the invention. Electrophotographic processes are known in the art; see, e.g., U.S. Pat. No. 2,297,691. Ionographic and electrographic processes are also well known in the art, see, e.g., U.S. Pat. Nos. 3,611,419; 3,564,556; 4,240,084; 4,569,584; 2,919,171; 4,524,371; 4,619,515; 4,463,363; 4,254,424; 4,538,163; 4,409,604; 4,408,214; 4,365,549; 4,267,556; 4,160,257; and 4,155,093.
The printing process using treated textiles does not require a separate curing step. For example, reaction of the colorant-reactive component of the coating agent in the coating composition with the colorant in the ink can occur at room temperature. However, exposure of the printed, coated textile substrate to heat (e.g., using conventional heat press processes) will speed the reaction of the dye with the coating agent.
After printing, the printed, coated textile substrates can be further treated using any compositions and processes that are compatible with the coating agents and coated textile substrates described herein.
Characteristics of Printed Images:
The printed, treated textile substrates as described herein interact rapidly and, in most cases, non-reversibly with a number of aqueous based dyes, providing a versatile medium for use with a wide variety of aqueous dyes. The printed, treated substrates are also water-resistant and bleed-resistant (as evidenced by small dot size measurements, i.e., less wicking action) and maintain a high degree of brightness for extended periods of time. Printed images formed upon the treated textile substrate are also fast-drying. Moreover, the coating composition can be used to prepare images with varying degree of gloss, depending upon variations in pigment.
Images printed upon a treated textile substrate of the type described herein can be analyzed for any of a number of representative features using standard analytical techniques to obtain measurements for optical density, water-fastness, chroma and hue (via LAB graphs), dot size, and the like. As can be seen on the basis of the results below, upon application of ink with an inkjet printer, substrates treated with a variety of coating compositions in accordance with the invention result in superior print images which are clear, durable, highly luminant, non-feathered, and water-resistant and/or water-fast.
In addition, images printed on treated textile substrates according to the present invention are also detergent resistant and/or detergent-fast. The detergent to which the images are resistant include a variety of commercially available detergents, (e.g., anionic detergents, cationic detergents, non-ionic detergents, amphoteric detergents, etc.). Anionic detergents to which the printed, treated textile substrates are resistant include, but are not necessarily limited to, alkyl aryl sulfonates (e.g., linear alkyl benzene sulfonate), alkyl aryl condensates (e.g., DDB (dodecyl benzene)), long chain (fatty) alcohol sulfates (e.g., having a chain of 12 to 18 carbon atoms), olefin sulfates and sulfonates, alpha olefin sulfate and sulfonates, sulfate monoglycerides, sulphate ethers, sulfosuccinates, alkane sulfonates, phosphate esters, alkyl isothionates, and sucrose esters.
The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to prepare and use the compounds disclosed and claimed herein. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in xc2x0 C. and pressure is at or near atmospheric.
Also, in these examples, unless otherwise stated, the abbreviations and terms employed have their generally accepted meanings. Abbreviations and tradenames are as follows (note that suppliers of each material are indicated as well):
Amres=azetidinium polymer (Georgia Pacific);
Gaufquat-755=cationic film-forming binder (ISP);
Gum 280=starch (Penford);
ISP 937=polyvinylpyrrolidone-dimethylaminomethacrylate (ISP);
Polectron=styrene/poly(vinyl pyrrolidone) copolymer (Polectron 430, ISP Technologies);
Polycup=azetidinium polymer;
PVOH=polyvinyl alcohol (Airvol 523S, Air Products);
PVP=polyvinyl pyrrolidone (Aldrich);
Sif=fumed silica (Aerosil MOX 170, Degussa);
Sip=precipitated silica (FK310, Degussa);
Tinopal=brightener (Ciba Additives);
Vantocil=3,12-diimino-2,4,11,13-tetraazatetradecanediimidamide, 20% aqueous solution (Vantocil IB, Zeneca, Inc.).
All patents, patent applications, journal articles and other references mentioned herein are incorporated by reference in their entireties.


There is provided a process for regenerating the activity of used metal catalysts for the hydrogenation of carbon monoxide comprising decreasing the hydrocarbon content thereof, calcining under an oxidant-containing atmosphere, impregnating with a solution of at least one of a metal compound, calcining under an oxidant-containing atmosphere and activating by contacting with a hydrogen-contacting gas at elevated temperatures to form an active catalyst. The process regenerates and enhances both supported and dispersed active metal (DAM) catalysts. Used catalysts enhanced by the process are initially treated to decrease their hydrocarbon content. The treatment may be carried out in a single reactor, or by carrying out up to all steps after catalyst may be withdrawn from a reactor and returned to at least one reactor, both preferably during operation thereof. Up to all steps may be effected in a subsequent reactor, or in specialized apparatus.

This invention relates to the production of higher hydrocarbons from synthesis gas utilizing a metal catalyst, particularly a cobalt catalyst.
The conversion of synthesis gas, i.e. carbon monoxide and hydrogen, to higher value products is well known and has been in commercial use for many years. Typical processes include, for example, methanol syntheses, higher alcohol synthesis, hydroformylation and Fischer-Tropsch synthesis. The synthesis gas mixture is contacted with a suitable catalyst typically comprising at least one Group VIII metals. Suitable Fischer-Tropsch catalysts comprise one or more catalytic Group VIII metals, such as iron, cobalt and nickel. For oxygenate synthesis, copper may be included as well.
There exist many variations of the formulation and preparation of catalysts useful for the conversion of synthesis gas. In general, the catalysts are classified into two broad types, unsupported metals, known as Dispersed Active Metals and a larger groups of catalysts metals supported on refractory oxides, such as silica, alumina, titania or mixtures thereof. Such catalysts, whether supported or unsupported may be enhanced by the addition of other metals or metal oxides, known as promoter metals.
Supports for catalyst metals are generally pilled, pelleted, beaded, extruded, spray-dried or sieved materials. There are many methodologies reported in the literature for the preparation of supported catalyst metals. Examples of such techniques include incipient wetness impregnation, slurry impregnation, coprecipitation, and the like. It will be appreciated that high metal loadings are generally obtained by coprecipitation or multiple, i.e. two or three, impregnations, whereas low metal loading catalysts may be prepared utilizing a single impregnation. The catalyst metal content of such catalysts may vary from one to fifty weight percent. Promoter metals or metal oxides may be added during the impregnation steps using soluble salts of the respective metals such as Pt, Pd, Rh, Ru, Os, Ir, Mo, W, Cu, Si, Cr, Ti, Mg, Mn, Zr, Hf, Al, Th and the like. It will further be appreciated that the choice of a particular metal combination and the amount thereof to be utilized will depend upon the specific application used in the conversion of synthesis gas. When a suitable support has been impregnated with one or more metals as by impregnation to form a catalyst precursor, it may be dried and then calcined in an oxygen-containing environment. The precursor is thereafter activated by reduction at elevated temperature in the presence of a reducing gas, typically containing hydrogen. Optionally, the catalyst is activated by contacting with hydrogen gas in presence of liquid hydrocarbons as disclosed in U.S. Pat. No. 5,292,705.
Regardless of the particular formulation and method of preparation, all catalysts lose productivity and/or selectivity in use. Selectivity may vary with the particular synthesis, but is generally expressed in terms of the percent of an undesirable substance in the product mix. For example, methane selectivity in a Fischer-Tropsch reaction is the percent of methane formed with the desired higher hydrocarbons. Degradation of the catalyst productivity may be due to a number of phenomena including, without limitation, contamination by catalytic poisons, deposition of carbonaceous residues, sintering, phase transformation of the metal or metals and the like. U.S. Pat. No. 5,283,216 discloses a method for rejuvenating a hydrocarbon synthesis catalyst, which has been subjected to reversible, partial deactivation in a slurry synthesis process by contacting the catalyst with hydrogen at elevated temperatures in presence of liquid hydrocarbons. However, not all deactivated catalysts are rejuvenable. It is commercially significant to extend the useful life of a used catalyst by various treatment procedures, for example, by means of regeneration.
There are catalyst regeneration methods described in the literature. Typically, these techniques rely on contacting the used catalyst at elevated temperature with an oxygen-containing gas and/or steam. Such treatment may be used to remove carbonaceous deposits and poisons additionally converting the metal to its corresponding oxide or oxides. The regenerated catalyst is thereafter reactivated by means of a reduction with a hydrogen-containing gas at elevated temperatures. Such a treatment is described, for example, in U.S. Pat. No. 4,399,234.
There are catalyst regeneration methods described in the literature. Typically, these techniques rely on contacting the used catalyst at elevated temperature with an oxygen-containing gas and/or steam. Such treatment may be used to remove carbonaceous deposits and poisons additionally converting the metal to its corresponding oxide or oxides. The regenerated catalyst is thereafter reactivated by means of a reduction with a hydrogen-containing gas at elevated temperatures. Such a treatment is described, for example, in U.S. Pat. No. 4,399,234.
U.S. Pat. No. 2,369,956 discloses a method for regeneration of a Fischer-Tropsch catalyst wherein the catalyst is dissolved and subsequently restored by re-precipitation of the catalytic metals. It was noted, however, that there were deposits remaining in the contact substance that materially increased the difficulty of restoring the catalyst. An example of such substances is the high molecular weight paraffins from the used catalyst that make it difficult to filter the metal salt produced by dissolution of the catalyst with acid. Since these materials make purification of the salt difficult, it is taught in the patent that hydrocarbon deposits on the catalyst must be initially removed by treatment with flowing hydrogen at elevated temperatures. The process of dissolution and re-precipitation may then be carried out. It is also taught in the patent that the pyrophoricity of the treated catalyst might be mitigated by treatment with steam prior to dissolution with strong acid. However, there is nothing in the patent regarding the efficiency of the disclosed process or the effect of exposing a catalyst support, such as described above, with strong acid.
U.S. Pat. No. 3,256,205 discloses a method of catalyst regeneration by treatment with a strong acid to the point of incipient wetness of the catalyst prior to removal of carbonaceous deposits accumulated during the catalytic cycle. It is specifically stated that removal of the carbonaceous deposits is detrimental in that the catalyst support would be damaged by contact with the strong acid utilized. Suitable acids are stated as having a dissociation constant greater that 10xe2x88x922 and are added to the catalyst in an amount varying from 0.5 stoichiometry to the stochiometry required to form the salts of the metals present in the catalyst.
It is clear from the foregoing discussion that there is not a clear incentive in the art to utilize any particular methodology in attempting to improve on the process of catalyst regeneration. In fact, the two patents discussed above would appear to negate each other since the first teaches that it is necessary to remove the carbonaceous deposits from the catalyst prior to treatment with acid, yet the second teaches that the carbonaceous deposits are necessary to prevent the acid from attacking the support structure. It also must be considered that it is generally not possible to use an aqueous-based solvent on a catalyst containing a waxy hydrocarbon deposit because it is hydrophobic as typically observed with Fischer-Tropsch catalysts. Hence, it would appear that the process of the second patent would not have applicability to a Fischer-Tropsch catalyst since a characteristic of the process is that the pores of the used catalyst are filled with wax that prevents good wetting by aqueous treatment solutions.
In hydroprocessing and oxidation catalysts, carbonaceous deposits are typically removed by calcination with an oxygen-containing gas at elevated temperatures. During such treatments, the metal-containing active phase of the catalyst is converted to oxides. To further improve the recovery of catalytic activity, contaminating metals are then removed by treatment with a basic solution, particularly one containing ammonium carbonate or sodium cyanide. Such treatments are illustrated, for example, in U.S. Pat. No. 4,795,726 and German Patent DE 43 02 992.
The modifying of hydroprocessing catalysts is taught, for example, in U.S. Pat. No. 5,438,028 wherein a finished catalyst is enhanced by the addition of a modifying agent in solution after which the catalyst is dried and optionally heated to a temperature of from 120xc2x0 C. to about 1000xc2x0 C. The process does not include a final reduction step to reactivate the catalyst. The modifiers disclosed in column three, with the exception of boron, which is not a metallic element, are all recognized poisons for Fischer-Tropsch catalysts. U.S. Pat. No. 5,389,502 discloses application of the same process for the enhancing of a hydroprocessing catalyst that has been regenerated by an oxidative treatment. The application of the modifying agent to the surface of the catalyst may be carried out to the point of incipient wetness. In both of these patents, the preferred modifying agent is boron.
U.S. Pat. No. 6,201,030 discloses a process and apparatus for regenerating a particulate catalyst during operation of a reactor. The process consists of withdrawing a partially spent catalyst as a slurry from a reactor to one of two regeneration stations, operating in parallel, treating the slurry with hydrogen and returning it to the reactor. The two regenerating stations are utilized in the alternative operating out of phase thereby facilitating continuous withdrawal and return of the slurry without substantial change in the liquid level within the reactor. The disclosed process effectively fails to provide any means of regenerating severely deactivated catalyst or of improving process reliability, such as by removing fines that may have formed in the turbulent environment of the reactor.
It is generally recognized that the economic worth of a given catalyst is a function of its original cost, its activity its regenerability and its value as a used catalyst, e.g. for metals recovery. It is apparent from the foregoing discussion that there has been considerable effort going back over many years to improve the economic worth of catalysts, since a process that will effectively increase the value of a catalyst and/or extend the useful life thereof before it must be disposed of through conventional metal recovery will significantly improve the worth of that catalyst. Effective catalyst regeneration effected while at the same time maintaining the reliability of the process requires the use of specific apparatus or combinations of specialized pieces of apparatus in combination with specific treatment techniques. Such process techniques and apparatus for carrying them out are provided in accordance with the present invention.
In accordance with the present invention, there is provided a significant improvement in the catalytic hydrogenation of carbon monoxide to form a mixture of hydrocarbons wherein the catalyst is a Fischer-Tropsch metal catalyst. The useful life of used Fischer-Tropsch catalysts is extended by a process of regeneration comprising: initially decreasing the hydrocarbon content thereof, calcining in the presence of an oxidant-containing atmosphere; impregnating with a solution of a compound at least one of a catalyst metal and a promoter metal for the catalyst; calcining again in the presence of an oxidant-containing atmosphere and finally reducing by treatment with a hydrogen-containing gas at elevated temperatures to form an active catalyst. Preferably, the catalyst particles are dried preceding each calcining step. The catalyst may also be passivated after the activation step.
The catalyst treated according to the invention is advantageously reused for the hydrogenation of carbon monoxide. Optionally, the catalyst is withdrawn from a carbon monoxide hydrogenation reactor and returned to at least one reactor, preferably during operation of the reactors. One up to all of the treating steps through activation of the catalyst may be carried out prior to withdraw, subsequent to return, or between withdraw and return. The withdraw and return steps may be carried out periodically or continuously.
The catalyst metal substrates treated in accordance with the process of the present invention are selected from the group consisting of Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, Re and Pt with cobalt and ruthenium being preferred. The process of the present invention is applicable to both supported and unsupported catalysts. Unsupported catalysts be in a variety of forms such as gauzes, fibers, wools and the like, but are preferably particulates since particulates have more surface available for enhancement of catalytic activity by the subject process
Preferred unsupported catalyst substrates are Dispersed Active Metals (xe2x80x9cDAMxe2x80x9d) which are primarily, i.e. at least about 50 wt. %, preferably at least 80 wt. %, composed of one or a mixture of metals such as described above and are, without further treatment, capable of catalyzing Fischer-Tropsch synthesis. DAM catalysts may be prepared by any of a number of art-recognized processes. The particle size range for the metal substrate particulates of the process is generally from about 0.1 micron to 5 millimeters, preferably from about 1 to 50 microns at their significant dimension. The term xe2x80x9csignificant dimensionxe2x80x9d as utilized herein will vary depending on the form of the substrate metal. Wherein the metal is a wire or a spheroid, the significant dimension is the diameter thereof, for an oval or a rhomboid or an irregular shape, the significant dimension is the smallest thickness.
Supported metal catalysts, which correspond essentially to reduced metals formed by one of the recognized techniques discussed above onto a suitable support structure, typically a refractory inorganic oxide, such as titania, silica, silica-alumina, aluminum and the like, are utilized in a broad range of applications such as hydrogenation of hydrocarbons and carbon monoxide. Titania is a preferred support material for the catalyst metal substrates treated in accordance with the present invention. Start-up procedures for such reactions, which may include specific activation sequences, are highly dependent upon the catalytic reaction, the process design and, in particular, the reaction vessel design and configuration. The slurry bubble column reactor, is a preferred vessel for carrying out carbon monoxide hydrogenation. The use of slurry bubble column for CO hydrogenation is particularly convenient in combination with the catalyst regeneration process of the present invention. In such reactors, the solid phase catalyst is dispersed or held in suspension in a liquid hydrocarbon phase by a gas phase, which continuously bubbles through the liquid phase. Supported catalysts useful for such applications contain at least 5 wt. %, preferably from 10 to 50 wt. %, of the catalyst metal in the reduced metallic form.
In the carbon monoxide hydrogenation reaction, syngas comprising a mixture of hydrogen and carbon monoxide is contacted with the catalyst thereby being converted into liquid and gaseous products, preferably C10+ liquid hydrocarbons, with shifting or non-shifting conditions, preferably the latter, wherein little or no water gas shift takes place. This hydrocarbon synthesis (xe2x80x9cHCSxe2x80x9d) process is generally carried out at temperatures of from about 160xc2x0 C. to 260xc2x0 C., pressures of from about 1 atm to about 100 atm, preferably from 10 atm to 40 atm, and gas space velocities of from about 100 V/Hr/V to about 40,000 V/Hr/V, preferably from about 1,000 V/Hr/V to about 15,000 V/Hr/V. The expression xe2x80x9cV/Hr/Vxe2x80x9d represents the standard volumes of gaseous carbon monoxide and hydrogen mixtures at 25xc2x0 C. and 1 atm per hour per volume of catalyst, respectively. The molar ratio of hydrogen to carbon monoxide in the syngas feed is about 2.1:1 for the production of higher hydrocarbons. This ratio may vary to from about 1:1 to 4:1, and preferably is from about 1.8:1 to 2.2:1. These reaction conditions are well known and a particular set of reaction conditions can readily be determined from the parameters given herein. The hydrocarbon-containing products formed in the process are essentially free of sulfur and nitrogen-containing contaminants.
The hydrocarbons produced in a process as described above are typically upgraded to more valuable products by subjecting all or a portion of the C5+ hydrocarbons to fractionation and/or conversion. By xe2x80x9cconversionxe2x80x9d is meant one or more operations in which the molecular structure of at least a portion of the hydrocarbons is changed and includes both non-catalytic processing, e.g. steam cracking, and catalytic processing, e.g. catalytic cracking, in which the portion, or fraction, is contacted with a suitable catalyst. If hydrogen is present as a reactant, such process steps are typically referred to as hydroconversion and variously as hydroisomerization, hydrocracking, hydrodewaxing, hydrorefining and the like. More rigorous hydrorefining is typically referred to as hydrotreating. These reactions are conducted under conditions well documented in the literature for the hydroconversion of hydrocarbon feeds, including hydrocarbon feeds rich in paraffins. Illustrative, but non-limiting, examples of more valuable products from such feeds by these processes include synthetic crude oil, liquid fuel, emulsions, purified olefins, solvents, monomers or polymers, lubricant oils, medicinal oils, waxy hydrocarbons, various nitrogen- or oxygen-containing products and the like. Examples of liquid fuels includes gasoline, diesel fuel and jet fuel, while lubricating oil includes automotive oil, jet oil, turbine oil and the like. Industrial oils include well drilling fluids, agricultural oils, heat transfer oils and the like.
The syngas utilized in carbon monoxide hydrogenation may be formed by various means known to those of ordinary skill in the art, such as a fluid bed syngas generating unit as is disclosed, for example, in U.S. Pat. Nos. 4,888,131, and 5,160,456. Regardless of the source, syngas typically may contain chemical species, such as hydrogen cyanide, which over time cause deactivation of the catalyst. Other deactivating chemical species may be formed during the carbon monoxide hydrogenation process itself. It is generally recognized that deactivation by those contaminants can be reversed by treatment with hydrogen thereby renewing the catalyst. Certain other causes of catalyst deactivation that cannot be renewed by hydrogen treatment are often addressed by steam treatment and/or calcination in air, such treatments being carried out at high temperatures.
Regardless of the particular formulation, method of preparation, morphology and size of catalysts, all catalysts will undergo a loss in productivity and/or selectivity in use. Selectivity may vary with the particular synthesis, but is generally expressed in terms of the percent of an undesirable substance in the product mixture. For example, methane is an undesired presence in the Fischer-Tropsch product mixture since the object of the process is to form higher molecular weight hydrocarbons. Hence, one method of expressing the worth of a catalyst is its methane selectivity, i.e. the amount of undesirable methane in the reactor mixture.
Degradation of catalyst productivity may be due to a number of phenomena including contamination by catalytic poisons, deposition of carbonaceous residues, sintering, phase transformation of the metal or metals in the catalyst and the like. Attrition of the catalyst particulates may also occur and may lead to operational problems in slurry reactors due to the accumulation of fines, particles typically less than 10 microns in size. It is commercially significant to improve the operational reliability of the process and extend the useful life of a given catalyst prior to its disposal, for example, by means of regeneration.
In accordance with the present invention, significant enhancement in both the productivity and methane selectivity of catalysts for the Fischer-Tropsch synthesis is realized by treating a used catalyst to decrease the hydrocarbon content thereof; calcining in the presence of an oxidant-containing atmosphere, impregnating with an solution of at least one compound chosen from a group consisting of catalyst metals and promoter metals for the catalyst, again calcining in the presence of an oxidant-containing atmosphere and finally reducing with hydrogen-containing gas at elevated temperatures to form an active catalyst.
The term xe2x80x9cusedxe2x80x9d catalyst in the context of the present invention means a catalyst that has been exposed to process conditions for the hydrogenation of carbon monoxide and, as a result, contains hydrocarbons. Used catalysts are first treated to decrease their hydrocarbon content, often referred to as xe2x80x9ccatalyst dewaxingxe2x80x9d. This may be carried out by one or more of several techniques. For example, separation may be effected by gravitational or centrifugal separation, which allows the hydrocarbon to be decanted, or removed by filtration, all of which require the hydrocarbons to be in a fluid state. The catalyst may also be treated with a solvent or supercritical fluid that effectively weakens the interaction of the hydrocarbons with the catalyst surface so that the liquid and solid phases can readily be separated in the same manner. This is referred to as solvent washing. Suitable solvents include, for example, paraffin solvents or naphthas, alcohols, and aromatic solvents. Supercritical fluids include, for example, carbon dioxide, light paraffins and cyclopentane.
Another means of decreasing the hydrocarbon content of used catalysts is to contact them with a hydrogen-containing gas at elevated temperatures, i.e. from about 200xc2x0 C. to 600xc2x0 C., preferably from 250xc2x0 C. to 400xc2x0 C. Typically, the hydrogen pressure would be from atmospheric to about 100 atm, preferably from atmospheric to 30 atm and gas hourly space velocities of from about 100 V/Hr/V to about 40,000 V/Hr/V, preferably from about 1,000 V/Hr/V to about 20,000 V/Hr/V, expressed as standard volumes of the hydrogen containing gas (25xc2x0 C., 1 atm.) per hour per volume of catalyst, respectively. This treatment reduces at least a portion of the catalytic metal to its metallic state.
Alternatively, the catalyst may be contacted with an oxygen-containing gas or steam at elevated temperatures to effectively decrease the hydrocarbon content. Solvent washing, oxygen and hydrogen treatment may also be advantageously combined in the subject process. The duration of the dewaxing is adjusted to produce a low residual carbon content, for example less than 5 wt. %, preferably less than 2 wt. % and typically ranges from 30 minutes to about 8 hours. If the dewaxing step involves or includes contacting the catalyst with a solvent or supercritical fluid, it is preferably dried prior to the impregnation step described below. The dewaxing process may be carried out in any suitable reactor, including the HCS reactor itself For example, fixed bed HCS reactors are well suited for dewaxing by contacting the catalyst at elevated temperatures with reactive gases, such as hydrogen or an oxidant-containing gas. When using slurry bubble column HCS reactors it is preferred to withdraw a mixture of catalyst and hydrocarbons, more preferably during operation of the reactor and further treat the catalyst in a dedicated processing device.
Any of the foregoing techniques for dewaxing the catalyst are followed by contacting with an oxidant-containing gas at elevated temperatures to carry out the initial oxidation of the catalytic metal to its oxide. This step is often referred to as calcination. Typically, the calcination step in the process is to contact the catalyst with an oxidant-containing gas at elevated temperatures, i.e. from about room temperature to 600xc2x0 C., preferably from room temperature to 400xc2x0 C. The oxidant is chosen from the group consisting of air, oxygen, ozone and nitrogen oxides. When oxygen or air is used, the oxygen concentration in the gas may vary from 10 ppm to 21%. Preferably the temperature and the concentration of the oxidant in the oxidant-containing gas may be gradually increased to provide for control of the exotherm generated by the oxidation of the catalyst, particularly when the dewaxing was effected by hydrogen treatment at elevated temperatures. In the latter case, it may be advantageous to treat the catalyst with steam prior to calcination. Typically, the oxidant-containing gas pressure would be from atmospheric to about 100 atm, preferably from atmospheric to 30 atm and gas hourly space velocities of from about 100 V/Hr/V to about 40,000 V/Hr/V, preferably from about 1,000 V/Hr/V to about 20,000 V/Hr/V, expressed as standard volumes of gas (25xc2x0 C., 1 atm.) per hour per volume of catalyst, respectively.
In accordance with the present invention, the calcined dewaxed catalyst is impregnated with a solution of at least one metal compound such as metal salts, metal complexes or metal-containing acids. The choice of solvent is dependent primarily on the capacity thereof to solubilize the metal compound. The solvent is preferably water, however, other solvents, e.g. certain organic solvents, may be combined therewith provided that they are miscible with water and do not introduce any known catalytic poison. Mixtures of water and immiscible organic solvents can be utilized as well as mixtures of water with solvents in combination with suitable dispersing or emulsifying agents present to form a continuous phase, i.e. an emulsion. Such other suitable liquids include hydrocarbons, particularly those derived from the Fischer-Tropsch synthesis, dense fluids, for example, supercritical fluids such as liquid phase light hydrocarbons, i.e. C3-5, alkanes, cyclopentane and the like. Preferred mixed liquids include, without any intended limitation, water/lower alkanols, water/Fischer-Tropsch products, and water/alkanols/alkanes.
The metal compounds utilized in the treatment solution are preferably those that contain a catalytic metal or a promotor metal for the hydrogenation of carbon monoxide. Such catalytic metals include, but are not limited to Co, Ni, Cu, Ru, Pt, Rh, Ir, Os, Pd, whereas promotor metals include, but are not limited to Mo, W, Si, Cr, Ti, Mg, Mn, Zr, Hf Al, Th, La, Ce, Y and the like. The non-metal ions of the metal salts utilized in the impregnation solution are preferably those that are easily removable from the catalyst without the deposition of any material that might have a deleterious effect on the performance of the catalyst. Ions containing sulfur, halogens, phosphorus and the like are to be avoided. Preferred non-metal ions include, without intended limitation, nitrate, nitrite, cyanide and the like. The ion component of the metal salts may also be a weak organic acid moiety, such as carbonate, carboxylates and the like. Salts of those metals listed above that are amphoteric may be formed with ions such as ammonium and alkyl ammonium, wherein alkyl ammonium includes mono-, di-, tri- and tetra-alkyl ammonium ions or any mixture thereof Particularly preferred metal salts include the nitrate, acetate and, where applicable, the ammonium salt.
The carboxylate ions of the metal salts are defined as the salts derived from weak organic acids such as carboxylic acids having the general formula Rxe2x80x94(COOH)n wherein n is 1-3 and R represents a cyclic or aliphatic, saturated or unsaturated moiety that may be substituted with one or more nitro, amino, hydroxyl or alkoxyl groups. Specific examples of suitable carboxylates include, without intended limitation, formates, acetates, citrate, succinate, malonate, propionate, butyrate, valerate, caproate, glutarate, adipate, lactate, benzoate, phthalate, salicylate, ascorbate, oxalate and the like. Preferred examples of suitable meta-containing acids include, without intended limitation, perrhenic acid, molybdic acids and tungstic acids. Metal complexes include, without intended limitation, metal acetylacetonate, metal ethylene diamine, metal diethylene triamines and the like.
The concentration of each of the constituents of the treatment solution will depend on a number of factors including the solubility of the complex, acid or salt, the volume of liquid utilized, the metal content and pore volume of the catalyst, the desired amount of metal to be added to the catalyst and the like. In general, the impregnating solution will contain from about 1 wt % to about 80 wt %, preferably from about 5 wt % to about 50 wt %, by weight of the metal compound. Typically, the amount of metal added to the catalyst will vary from about 1 wt % to about 80 wt % of the total metal content of the catalyst being impregnated, preferably 10 to 30 wt %. The solution of the metal compounds may be prepared by simply dissolving them in the selected solvent, or by combining solutions of suitable reactants.
The impregnation will typically be carried out until the catalyst substrate has absorbed a volume of impregnating solution equal to at least about 10% of its calculated pore volume, preferably to where conditions of incipient wetness are attained. By incipient wetness is meant that the substrate catalyst has adsorbed an amount of solution generally equivalent to its calculated pore volume. Pore volume is a discernible quantity that can be measured directly or indirectly by known techniques such as porosimetry. The volume of impregnating solution contemplated will vary from 10% to 5,000% of the calculated pore volume of the catalyst. Preferably, the volume of treatment solution will be from 30% to 1000%, most preferably from about 70% to 100% of the calculated pore volume of the catalyst.
The impregnating solution will remain in contact with the catalyst for from 1 minute to 24 hours, preferably from about 5 to 120 minutes. The time required for the treatment will vary depending on factors such as the quantity of the catalyst being treated, the composition and volume of the impregnating solution, the reactor configuration and the like. The treatment is carried out at a temperature from about 0xc2x0 C. to about 100xc2x0 C., preferably from room temperature, i.e. 20xc2x0-25xc2x0 C., to about 80xc2x0 C. The pressure is not particularly critical and can be from 0.1 to 100 atmospheres, with atmospheric pressure being preferred. The atmosphere is preferably air, but any non-reactive atmosphere is suitable. By non-reactive we mean an atmosphere that will not react with the solution during the impregnation step.
In the subject process, the catalyst impregnated as described above is then calcined under an oxidant-containing atmosphere prior to the activation step, preferably after drying the catalyst. The atmosphere is preferably air, but may be an inert atmosphere containing a controlled amount of oxygen, e.g. such as would be produced as a product gas stream or a waste gas stream from an air separation plant. Such controlled oxidant-containing atmospheres would contain from 10 ppm to 21% by volume, preferably from about 1% to 21% by volume, oxygen with the remainder being a non-oxidative gas, preferably an inert gas, such as nitrogen. The gas flow in the furnace is from about 100 to 10,000, preferably from about 1,000 to 5,000 GSHV. The calcination is carried out at elevated temperatures, i.e. from about 150xc2x0 C. to about 600xc2x0 C., preferably from about 200xc2x0 C. to 450xc2x0 C., for from about 1 to 8 hours, preferably from 1 to about 4 hours. Suitable apparatus for the calcining step may be a rotary calciner such as described in Perry""s chemical Engineer""s Handbook, Seventh Edition, Chapter 12, McGraw-Hill, N.Y.(1997), a fluidized processor as will be described below or an HCS reactor itself.
The treated catalyst particles are activated by reduction with hydrogen-containing gas at elevated temperatures, i.e. from about 200xc2x0 C. to 600xc2x0 C., preferably from about 250xc2x0 C. to 400xc2x0 C. Hydrogen partial pressure during the reduction would range from about 1 to 100 atmospheres, preferably from about 1 to 40 atmospheres, and the gas hourly space velocities would be from about 100 V/Hr/V to about 40,000 V/Hr/V, preferably from about 1,000 V/Hr/V to about 20,000 V/Hr/V, expressed as standard volumes of the gas or gas mixtures (25xc2x0 C., 1 atm) per hour per volume of catalyst, respectively. The resulting catalyst particles regenerated in accordance with the present invention have been found to have a significant portion of their original activity restored, both in terms of production of the desired hydrocarbons and in methane selectivity.
It is a further optional step within the scope of the present invention to passivate the treated catalyst after the activation with hydrogen-containing gas has been carried out. The passivation may be carried out by contacting the catalyst with a gas containing carbon monoxide, or carbon monoxide and hydrogen, under conditions such that carbon monoxide does not significantly decompose and is not hydrogenated to a material degree. Such conditions, for example, would be a temperature below about 150xc2x0 C., preferably between about 25xc2x0 C. and 100xc2x0 C., and pressure below about 20 atm, particularly between about 1 and 10 atm and the gas hourly space velocities would be from about 1 V/Hr/V to about 1,000 V/Hr/V, preferably from about 10 V/Hr/V to about 500 V/Hr/V, expressed as standard volumes of the gas or gas mixtures (25xc2x0 C., 1 atm) per hour per volume of catalyst, respectively. It will be appreciated that some decomposition or hydrogenation, respectively, of the carbon monoxide may take place regardless of the precautions taken by the operator. However, it has been found that, typically, significant decomposition/hydrogenation will not take place wherein the concentration of carbon monoxide or carbon monoxide and hydrogen in the feed gas does not exceed about 5% by volume. Other passivating agents include, for example, traces of oxygen or carbon dioxide.
Often in commercial usage, a plurality of reactors is operated in parallel and in series. In accordance with the present invention, the treated catalyst is reused for the hydrogenation of carbon monoxide. The treatment may be effected in one or more reactors or in combination with other specialized apparatus as will be discussed below. All treating steps may be carried out in a single HCS reactor. Alternatively, the catalyst may be withdrawn and returned to at least one of said HCS reactors. It is within the scope of the present invention to carry out any up to all of the treating steps in the initial reactor prior to the withdrawing step, or in the subsequent one or more reactors after the returning step. Further, one or more of the treating steps may be carried out in the initial reactor or the subsequent one or more reactors and the remainder carried out in other specialized apparatus as will be described below. For example, when using a fixed bed HCS reactor, it is preferred to carry out at least the dewaxing step in the original reactor since it is well suited to such treatment.
When using slurry reactors, it is preferred to initially withdraw the catalyst as a mixture with hydrocarbon, typically molten wax, and carry out at least one of the treatment steps in specialized apparatus or the subsequent one or more reactors. While the amount of catalyst removed can vary within a wide range, those of ordinary skill in the art will appreciate that it is necessary that sufficient catalyst remain in the reactor to sustain the desired level of production. Generally, from about 0.01 wt. % to about 10 wt. % of the catalyst will be withdrawn from the reactor at a given point in time during production. It is not intended that such amount of catalyst be removed in a single quantity. Rather, portions of the withdrawn catalyst will be at various stages of the process of the invention at any given time so that, when a portion is returned to the subsequent one or more reactor, an estimated like amount can be withdrawn. It will be appreciated that, as utilized herein, the term xe2x80x9creactorxe2x80x9d is not intended to be restricted to the singular and includes both the singular and the plural. When using the slurry reactor, it is a preferred option to continuously withdraw and replace catalyst while the reactor(s) is (are) in production.
The hydrocarbon content of the mixture withdrawn from the slurry reactor is essentially similar to that of the reactor at the mixture collection port. It is recognized that the hydrocarbon content of the mixture depends upon the type of reactor utilized, its configuration and operating conditions. For example, it is expected that a lower hydrocarbon content will be obtained when operating a bubble column reactor with a slumped bed as opposed to operating it with a dispersed bed. The mixture withdrawn from the reactor may be initially treated by conventional techniques, for example by physical screening, to separate the fines from the remaining catalyst particles. Although the criteria for what are classified as fines particles may vary with the reactor, generally fines are recognized as particles smaller than 10 microns.
Formation and accumulation of fines through attrition of the catalyst particles can result from normal operation of the reactor or from processing of the withdrawn catalyst. Accumulation of fines in the reactor can lead to operational problems. Many methods are recognized as useful for removing fines. For example, fines may be removed by classifying or screening of dry flowing powders or decantation of catalyst slurry after a specified catalyst settling time. Even though the removal of fines may be effected on dry catalyst or catalyst slurry obtained prior to returning the catalyst to a reactor, it is preferred to remove the fines during or after the dewaxing step. The activity of the supported catalyst particles separated from the fines will be enhanced in accordance with the subject invention. The fines, which may be composed of both catalyst and support material, may be processed into, for example, useful catalyst or further processed for metal recovery.
As stated above, the treatment process in accordance with the present invention may be carried out in one or more HCS reactors, in a series of apparatus particularly adapted to a specific step or steps or any combination thereof. For example, the step of decreasing the hydrocarbon content of a catalyst withdrawn from an HCS slurry reactor may advantageously be carried out in a mixer-settler vessel as is described in Perry""s Chemical Engineers"" Handbook, Seventh Edition, Chapter 18, McGraw-Hill, N.Y. 1997. Such a vessel would typically be provided with a heating jacket, agitator and liquid phase withdrawing means. After treatment therein, the catalyst would be withdrawn, typically as a slurry, and be passed to a processor for solvent removal and drying.
The processor is a device that can impart mixing and fluidization to the process. It would be configured to enhance heat transfer, mixing liquid-contacting, and gas solid transfer. Examples of suitable processors are gas fluidized beds, vibro-fluidized beds, mechanical blenders, e.g. double cone, vee, ribbon and the like and mixers such as plow, planetary, paddle and the like. These devices fluidize the processed material by passing a gas directly through it, by mechanical agitation or by a combination of both actions. Processing in such a device causes the material being treated to attain fluid-like properties resulting in intimate contact between each particle and the gas stream thus creating an extremely efficient mass and heat transfer. A devices that provides at least mechanical fluidization is particularly preferred since, although both a slurry and a powder can be made to readily flow, during the drying process from one to the other, the material will pass through what is termed the xe2x80x9cmud stagexe2x80x9d where it is extremely difficult to fluidize. Hence, for the drying operation wherein a catalyst is in a slurry, the processor should have at least mechanical and, preferably, both mechanical and gas fluidization.
A preferred processor for carrying out the subject process is the plow mixer, a device with a jacketed horizontal cylinder with an axial agitator shaft containing several sets of blade or triangular agitators. Such a device will typically also have both gas and liquid inlets and outlets as well as an inlet and outlet for the solid material being processed. While this is a preferred device, any comparable mixer possessing the foregoing capabilities could be utilized as well, provided that it has the capacity to continue to fluidize the material through the mud stage of drying. Such a device will also facilitate the solvent washing that can be part of the process of decreasing the hydrocarbon content of the material as well as the subsequent hydrogen treatment at elevated temperatures. This is a preferred method of decreasing hydrocarbon content since it permits recovery of the wax, an important consideration.
The next step, calcining of the dried catalyst may be carried out in the processor, or is a suitable device as described above. Following calcination, the treatment with the impregnation solution as described above can likewise be carried out in a mechanical mixer, such as a plow mixer for the reasons previously stated. The mixer is advantageous in that the liquid may be added while the material is in a fluidized condition. Because the mixer has inlet and outlet means for gas, when the material has been impregnated to the desired degree, the subsequent calcination in an oxidant-containing atmosphere may be affected therein as well. The material may remain in the processor, or may be removed for further processing, for example, the removal of fines, drying and calcination steps discussed above. All of these operations may be carried out in the processor if desired. However, suitable devices for removal of fines from dry particulate solids, for example by sieving, elutriation from fluidized beds, gas classification and the like, are described in Perry""s Chemical Engineers"" Handbook, Seventh Edition, Chapters 17, 19 and 20, McGraw-Hill, N.Y. 1997.
The final activation of the material to form an active catalyst can be carried out in a fluidized processor as described above. A larger variety of devices may be utilized for this step, however, since the material does not pass through a mud phase, hence gas fluidizers can be utilized for the excellent solidlo gas contact they provide. It is particularly useful when the catalyst has undergone the decrease of hydrocarbon content in a fixed bed reactor. Further, a gas fluidizer may be utilized for the activating the catalyst, reducing a fresh batch of catalyst and optionally for the passivation step described above as, again, the material does not transcend through a mud phase. It can be appreciated, that a series of varied devices can be utilized to carry out the process of the present invention, which may be advantageous for large-scale operations. However, as described above, it is also possible to carry out the entire process of regeneration of the used catalyst in a mechanical fluidizer having the capabilities of solid, gas and liquid transfer.
It is understood that various other embodiments and modifications in the practice of the invention will be apparent to, and can be readily made by, those of ordinary skill in the art without departing form the scope and spirit of the invention as described above. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the exact description set forth above, but rather that the claims be construed as encompassing all of the features of patentable novelty that reside in the present invention, including all the features and embodiments that would be treated as equivalents thereof by those skilled in the art to which the invention pertains. The invention is further described with reference to the following experimental work.

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