The present invention relates to a process for cracking a hydrocarbon feedstock in a steam cracker unit, comprising the following steps of:                feeding a liquid hydrocarbon feedstock to a hydrocracking unit,        separating the stream thus hydrocracked in said hydrocracking unit into a high content aromatics stream and a gaseous stream comprising C2-C4 paraffins, hydrogen and methane,        separating C2-C4 paraffins from said gaseous stream,        feeding said C2-C4 paraffins thus separated to the furnace section of a steam cracker unit.

The present invention relates to a process for cracking a hydrocarbon feedstock in a steam cracker unit.
Conventionally, crude oil is processed, via distillation, into a number of cuts such as naphtha, gas oils and residua. Each of these cuts has a number of potential uses such as for producing transportation fuels such as gasoline, diesel and kerosene or as feeds to some petrochemicals and other processing units.
Light crude oil cuts such a naphthas and some gas oils can be used for producing light olefins and single ring aromatic compounds via processes such as steam cracking in which the hydrocarbon feed stream is evaporated and diluted with steam then exposed to a very high temperature (800° C. to 860° C.) in short residence time (<1 second) furnace (reactor) tubes. In such a process the hydrocarbon molecules in the feed are transformed into (on average) shorter molecules and molecules with lower hydrogen to carbon ratios (such as olefins) when compared to the feed molecules. This process also generates hydrogen as a useful by-product and significant quantities of lower value co-products such as methane and C9+ Aromatics and condensed aromatic species (containing two or more aromatic rings which share edges).
Typically, the heavier (or higher boiling point), higher aromatic content streams, such as residua are further processed in a crude oil refinery to maximize the yields of lighter (distillable) products from the crude oil. This processing can be carried out by processes such as hydro-cracking (whereby the hydro-cracker feed is exposed to a suitable catalyst under conditions which result in some fraction of the feed molecules being broken into shorter hydrocarbon molecules with the simultaneous addition of hydrogen). Heavy refinery stream hydrocracking is typically carried out at high pressures and temperatures and thus has a high capital cost.
An aspect of such a combination of crude oil distillation and steam cracking of the lighter distillation cuts is the capital and other costs associated with the fractional distillation of crude oil. Heavier crude oil cuts (i.e. those boiling beyond ˜350° C.) are relatively rich in substituted aromatic species and especially substituted condensed aromatic species (containing two or more aromatic rings which share edges) and under steam cracking conditions these materials would yield substantial quantities of heavy by products such as C9+ aromatics and condensed aromatics. Hence, a consequence of the conventional combination of crude oil distillation and steam cracking is that a substantial fraction of the crude oil is not processed via the steam cracker as the cracking yield of valuable products from heavier cuts is not considered to be sufficiently high.
Another aspect of the technology discussed above is that even when only light crude oil cuts (such as naphtha) are processed via steam cracking a significant fraction of the feed stream is converted into low value heavy by-products such as C9+ aromatics and condensed aromatics. With typical naphthas and gas oils these heavy by-products might constitute 2% to 25% of the total product yield (Table VI, Page 295, Pyrolysis: Theory and Industrial Practice by Lyle F. Albright et al, Academic Press, 1983). Whilst this represents a significant financial downgrade of expensive naphtha in lower value material on the scale of a conventional steam the yield of these heavy by-products does not typically justify the capital investment required to up-grade these materials (e.g. by hydrocracking) into streams that might produce significant quantities of higher value chemicals. This is partly because hydrocracking plants have high capital costs and, as with most petrochemicals processes, the capital cost of these units typically scales with throughput raised to the power of 0.6 or 0.7. Consequently, the capital costs of a small scale hydro-cracking unit are normally considered to be too high to justify such an investment to process steam cracker heavy by-products.
Another aspect of the conventional hydrocracking of heavy refinery streams such as residua is that this is typically carried out under compromise conditions chosen to achieve the desired overall conversion. As the feed streams contain a mixture of species with a range of easiness of cracking this result in some fraction of the distillable products formed by hydrocracking of relatively easily hydrocracked species being further converted under the conditioned necessary to hydrocrack species more difficult to hydrocrack. This increases the hydrogen consumption and heat management difficulties associated with the process and also increases the yield of light molecules such as methane at the expense of more valuable species.
A feature of such a combination of crude oil distillation and steam cracking of the lighter distillation cuts is that steam cracking furnace tubes are typically unsuitable for the processing of cuts which contain significant quantities of material with a boiling point greater than ˜350° C. as it is difficult to ensure complete evaporation of these cuts prior to exposing the mixed hydrocarbon and steam stream to the high temperatures required to promote thermal cracking. If droplets of liquid hydrocarbon are present in the hot sections of cracking tubes coke is rapidly deposited on the tube surface which reduces heat transfer and increases pressure drop and ultimately curtails the operation of the cracking tube necessitating a shut-down of the tube to allow for decoking. Due to this difficulty a significant proportion of the original crude oil cannot be processed into light olefins and aromatic species via a steam cracker.
US2009173665 relates to a catalyst and process for increasing the monoaromatics content of hydrocarbon feedstocks that include polynuclear aromatics, wherein the increase in monoaromatics can be achieved with an increase in gasoline/diesel yields and while reducing unwanted compounds thereby providing a route for upgrading hydrocarbons that include significant quantities of polynuclear aromatics.
FR 2 364 879 relates to a selective process for producing light olefinic hydrocarbons having 2 and 3 carbon atoms respectively per molecule, particularly ethylene and propylene, which are obtained by hydrogenolysis or hydrocracking followed with steam-cracking.
DE 2708412 relates to an integrated process for producing ethylene comprising a step of introducing a hydrocarbon feed stock in a hydrocracking reactor free of non-thermal hydrocracking catalyst under conditions of temperature in the range of from 510-815° C., a pressure in the range of from 15-70 atm and a residence time in the range of from 5-60 sec, a step of separating aromatic hydrocarbons, a step of separating a stream consisting essentially of hydrocarbons C2-C3 by cryogenic techniques; and introducing said stream into a cracking zone maintained under conditions for converting hydrocarbons in a stream mainly comprising ethylene.
U.S. Pat. No. 3,944,481 relates to a process for converting crude oil fractions into an olefin product by hydrocracking the crude oil fractions to C2-C5 paraffins and thermally cracking these to a C2-C3 olefin mixture, wherein hydrogen, methane, and the C6-C9 components are separated from the C2-C5 fraction and the C2-C5 fraction is then mixed with steam and injected into the thermal cracker.
EP 0023802 relates to a process for producing light paraffins which comprises hydrocracking a crude oil fraction boiling in the range 93° C. to 538° C. at a pressure above 2859 kPa, a temperature of 300 to 565° C., a hydrogen/hydrocarbon mole ratio of 4:1 to 50:1 and a residence time of 1 to 180 seconds over a catalyst, and recovering a C2-C5 alkane product, wherein said alkane product is thermally cracked to ethylene and propylene.
GB 1148967 relates to a process for the preparation of ethylene, comprising hydrocracking a hydrocarbon oil boiling below 250° C. at elevated temperature in the presence of hydrogen and a catalyst, separating a hydrocarbon mixture from the reaction product of the hydrocracking, thermally cracking this mixture at an elevated temperature in the presence of steam, and separating ethylene from the reaction product of the thermal cracking. The hydrocarbon mixture formed from the hydrocarbon oil as a result of the hydrocracking is present as a liquid in the gas/liquid separating system and is passed through a line to the steam cracking furnace.
GB 1250615 relates to an aromatic extraction process whereby aromatics can be extracted from aromatic-containing hydro crackates
U.S. Pat. No. 3,842,138 relates to a method of thermal cracking in the presence of hydrogen of a charge of hydrocarbons of petroleum wherein the hydrocracking process is carried out under a pressure of 5 and 70 bars at the outlet of the reactor with very short residence times of 0.01 and 0.5 second and a temperature range at the outlet of the reactor extending from 625 to 1000° C.
An object of the present invention is to provide a method for upgrading naphtha to aromatics and steam cracker feedstock comprising C2-C4 paraffins.
Another object of the present invention is to provide a method for converting relatively heavy liquid feeds, such as diesel and atmospheric gasoil to produce a hydrocracking product stream comprising mono-aromatic hydrocarbons and C2-C4 paraffins.
Another object of the present invention is to process a heavy liquid feedstock while minimizing the production of heavy C9+ byproducts.
The present invention relates to a process for cracking a hydrocarbon feedstock in a steam cracker unit, comprising the following steps of:
feeding a liquid hydrocarbon feedstock to a hydrocracking unit,
separating the stream thus hydrocracked in said hydrocracking unit into a high content aromatics stream and a gaseous stream comprising C2-C4 paraffins, hydrogen and methane,
separating C2-C4 paraffins from said gaseous stream,
feeding said C2-C4 paraffins thus separated to the furnace section of a steam cracker unit.
On basis of such a process one or more of the presents objects are achieved.
According to such a method the hydrocracked feedstock can be used as a feedstock for a steam cracker unit. The aromatics get separated from the gaseous stream and will not be sent to the steam cracker unit but will be further processed in a separate unit. Methane and other light components can be pretreated in a separator to separate C2-C4 paraffins from said gaseous stream and the C2-C4 paraffins be sent to a steam cracker unit. The typical gas produced in a steam cracker unit usually contains a lot of hydrogen often fueled to satisfy the energy demand of the steam cracker. This therefore will improve the energy performance and hydrogen balance.
Consequently the main aim of the present invention is to produce LPG (Ethane, propane, butanes), which can be processed in a gas steam cracker unit. By placing a suitably designed hydrocracker unit in front of a gas steam cracker, and feeding said hydrocracker unit with a liquid hydrocarbon feedstock, such as for instance naphtha, it effectively acts as a feed pretreatment unit to the gas steam cracker making an otherwise unsuitable feed suitable for processing in existing gas steam crackers. Potential feeds to be processed according to the present method could be hydrocarbon streams such as diesel, kerosene, atmospheric gasoils (AGO), gas condensates, naphtha and waxy materials.
According to the present invention the process for producing C2-C4 olefins and aromatic hydrocarbons having one aromatic ring comprises a step of contacting a liquid hydrocarbon feedstock having a boiling point in the range of 20-350° C. in the presence of hydrogen with a hydrocracking catalyst to produce a hydrocracking product stream comprising aromatic hydrocarbons having one aromatic ring and C2-C4 paraffins, a step of separating the aromatic hydrocarbons having one aromatic ring from the hydrocracking product stream; and a step of separating the C2-C4 paraffins from the hydrocracking product stream and preferably feeding said separated C2-C4 paraffins into dedicated pyrolysis furnaces to conduct a pyrolysis reaction to produce a pyrolysis product stream comprising C2-C4 olefins.
In preferred embodiments a portion of the hydrogen comprised in the pyrolysis product stream is separated and fed to the hydrocracking step, C5+ hydrocarbons comprised in the pyrolysis product stream are separated and are fed to the hydrocracking step, aromatic hydrocarbons having one aromatic ring are separated from the hydrocracking product stream using separator, e.g. a distillation process or a solvent extraction process, C2-C4 paraffins are separated from the hydrocracking product stream gaseous fraction using a separator, e.g. a distillation process.
According to other preferred embodiments one can pretreat the hydrocarbon feed (e.g. by solvent extraction) to separate the aromatics+naphtenes (extract) and the paraffins (raffinate). Consequently, one could process the aromatics+naphtenes stream via a hydrocracker (to do the HDS and remove any traces of paraffins and dehydrogenate the naphtenes to make sales specification aromatics) and send the paraffins to the steam cracker to make light olefins. This combination of processes will minimize the hydrogen consumption and minimize fuel gas make from the steam cracker unit.
As discussed above, the present process further comprises separating said high content aromatics stream into a stream of heavy aromatics and a stream high in mono-aromatics, especially using a separator of the distillation type.
According to another embodiment of the present invention the present process further comprises feeding the gaseous stream, i.e. predominantly comprising C2-C4 paraffins, to a dehydrogenation unit for obtaining hydrogen, C3-olefins and C4-olefins. This means that the gaseous stream produced in the hydrocracking unit can be sent to different routes, that is to the steam cracker unit or to the dehydrogenation unit. This choice of routes provides flexibility to the present method. Processes for the dehydrogenation of lower alkanes such as propane and butanes are described as lower alkane dehydrogenation process.
In a preferred embodiment the present process further comprises separating C2-C4 paraffins into individual streams, each stream predominantly comprising C2 paraffins, C3 paraffins and C4 paraffins, respectively, and feeding each individual stream to a specific furnace section of said steam cracker unit. This means that a C2 stream, which stream predominantly comprises C2 paraffins, is sent to a specific C2 furnace section of the steam cracker unit. The same holds for a C3 stream and a C4 stream. Such a separation into specific streams has a positive influence on the product yield of the steam cracker unit. In a preferred embodiment the C3 stream and the C4 stream, as separate streams or as a combined C3+C4 stream, are sent to a dehydrogenation unit. More in detail, the present method further comprises separating C2-C4 paraffins into individual streams, each stream predominantly comprising C2 paraffins, C3 paraffins and C4 paraffins, respectively, and feeding the predominantly comprising C2 paraffin stream to a steam cracker whilst feeding the predominantly comprising C3 paraffin stream to a propane dehydrogenation unit and feeding the predominantly comprising C4 paraffin stream to a butane dehydrogenation unit.
As discussed above, the gaseous stream produced in the hydrocracking unit contains a broad spectrum of hydrocracked products. In a preferred embodiment not only the C2-C4 paraffins will be recovered from the gaseous product but the other valuable components, such as hydrogen and methane as well. The hydrogen and methane containing stream will preferably be recycled to the hydrocracking unit. In addition, it is also preferred to have a purge stream in the hydrocracking unit to prevent accumulation of unwanted components.
The method for separating said C2-C4 paraffins from said gaseous stream is preferably carried out by a separation of the type chosen from cryogenic distillation or solvent extraction.
The preferred process conditions in said hydrocracking include a temperature of 300-550° C., a pressure of 300-5000 kPa gauge and a Weight Hourly Space Velocity of 0.1-10 h−1. More preferred hydrocracking conditions include a temperature of 350-550° C., a pressure of 600-3000 kPa gauge and a Weight Hourly Space Velocity of 0.2-2 h−1.
The reactor type design of the said hydrocracking unit is chosen from the group of the fixed bed type, ebulating bed reactor type and the slurry type, wherein the fixed bed type is preferred.
Examples of the hydrocarbon feedstock to said hydrocracking unit are of the type naphtha, kerosene, diesel, atmospheric gas oil (AGO), gas condensates, naphtha, waxes, or combinations thereof.
The separation of the high content aromatics stream is preferably of the distillation type.
According to a preferred embodiment the process according to the present invention further comprises separating C7 to C9 aromatics, for example toluene and xylene rich fraction, from the stream high in mono-aromatics, and converting said C7 to C9 aromatics into a benzene rich fraction.
Moreover, the process according to the present invention further comprises recovering a portion of hydrogen from the product stream of said steam cracker unit and feeding said hydrogen to said hydrocracking unit.
As discussed above, the present method further comprises recovering C5+ hydrocarbons from the product stream of said steam cracker unit and feeding said C5+ hydrocarbons to said hydrocracking unit.
The term "crude oil" as used herein refers to the petroleum extracted from geologic formations in its unrefined form. Any crude oil is suitable as the source material for the process of this invention, including Arabian Heavy, Arabian Light, other Gulf crudes, Brent, North Sea crudes, North and West African crudes, Indonesian, Chinese crudes and mixtures thereof, but also shale oil, tar sands and bio-based oils. The crude oil is preferably a conventional petroleum having an API gravity of more than 20° API as measured by the ASTM D287 standard. More preferably, the crude oil used is a light crude oil having an API gravity of more than 30° API. Most preferably, the crude oil comprises Arabian Light Crude Oil. Arabian Light Crude Oil typically has an API gravity of between 32-36° API and a sulfur content of between 1.5-4.5 wt-%.
The term "petrochemicals" or "petrochemical products" as used herein relates to chemical products derived from crude oil that are not used as fuels. Petrochemical products include olefins and aromatics that are used as a basic feedstock for producing chemicals and polymers. High-value petrochemicals include olefins and aromatics. Typical high-value olefins include, but are not limited to, ethylene, propylene, butadiene, butylene-1, isobutylene, isoprene, cyclopentadiene and styrene. Typical high-value aromatics include, but are not limited to, benzene, toluene, xylene and ethyl benzene.
The term "fuels" as used herein relates to crude oil-derived products used as energy carrier. Unlike petrochemicals, which are a collection of well-defined compounds, fuels typically are complex mixtures of different hydrocarbon compounds. Fuels commonly produced by oil refineries include, but are not limited to, gasoline, jet fuel, diesel fuel, heavy fuel oil and petroleum coke.
The term "aromatic hydrocarbons" or "aromatics" is very well known in the art. Accordingly, the term "aromatic hydrocarbon" relates to cyclically conjugated hydrocarbon with a stability (due to delocalization) that is significantly greater than that of a hypothetical localized structure (e.g. Kekulé structure). The most common method for determining aromaticity of a given hydrocarbon is the observation of diatropicity in the 1H NMR spectrum, for example the presence of chemical shifts in the range of from 7.2 to 7.3 ppm for benzene ring protons. The terms "naphthenic hydrocarbons" or "naphthenes" or "cycloalkanes" is used herein having its established meaning and accordingly relates types of alkanes that have one or more rings of carbon atoms in the chemical structure of their molecules.
The term "olefin" is used herein having its well-established meaning. Accordingly, olefin relates to an unsaturated hydrocarbon compound containing at least one carbon-carbon double bond. Preferably, the term "olefins" relates to a mixture comprising two or more of ethylene, propylene, butadiene, butylene-1, isobutylene, isoprene and cyclopentadiene.
The term "LPG" as used herein refers to the well-established acronym for the term "liquefied petroleum gas". LPG generally consists of a blend of C2-C4 hydrocarbons i.e. a mixture of C2, C3, and C4 hydrocarbons.
The term "BTX" as used herein relates to a mixture of benzene, toluene and xylenes.
As used herein, the term "C # hydrocarbons", wherein "#" is a positive integer, is meant to describe all hydrocarbons having # carbon atoms. Moreover, the term "C #+ hydrocarbons" is meant to describe all hydrocarbon molecules having # or more carbon atoms. Accordingly, the term "C5+ hydrocarbons" is meant to describe a mixture of hydrocarbons having 5 or more carbon atoms. The term "C5+ alkanes" accordingly relates to alkanes having 5 or more carbon atoms.
As used herein, the term "hydrocracker unit" or "hydrocracker" relates to a refinery unit in which a hydrocracking process is performed i.e. a catalytic cracking process assisted by the presence of an elevated partial pressure of hydrogen; see e.g. Alfke et al. (2007) loc.cit. The products of this process are saturated hydrocarbons and, depending on the reaction conditions such as temperature, pressure and space velocity and catalyst activity, aromatic hydrocarbons including BTX. The process conditions used for hydrocracking generally includes a process temperature of 200-600° C., elevated pressures of 0.2-20 MPa, space velocities between 0.1-10 h−1
Hydrocracking reactions proceed through a bifunctional mechanism which requires a acid function, which provides for the cracking and isomerization and which provides breaking and/or rearrangement of the carbon-carbon bonds comprised in the hydrocarbon compounds comprised in the feed, and a hydrogenation function. Many catalysts used for the hydrocracking process are formed by composting various transition metals, or metal sulfides with the solid support such as alumina, silica, alumina-silica, magnesia and zeolites.
As used herein, the term "feed hydrocracking unit" or "FHC" refers to a refinery unit for performing a hydrocracking process suitable for converting a complex hydrocarbon feed that is relatively rich in naphthenic and paraffinic hydrocarbon compounds—such as straight run cuts including, but not limited to, naphtha- to LPG and alkanes. Preferably, the hydrocarbon feed that is subject to feed hydrocracking comprises naphtha. Accordingly, the main product produced by feed hydrocracking is LPG that is to be converted into olefins (i.e. to be used as a feed for the conversion of alkanes to olefins). The FHC process may be optimized to keep one aromatic ring intact of the aromatics comprised in the FHC feedstream, but to remove most of the side-chains from said aromatic ring. In such a case, the process conditions to be employed for FHC are comparable to the process conditions to be used in the GHC process as described herein above. Alternatively, the FHC process can be optimized to open the aromatic ring of the aromatic hydrocarbons comprised in the FHC feedstream. This can be achieved by modifying the GHC process as described herein by increasing the hydrogenation activity of the catalyst, optionally in combination with selecting a lower process temperature, optionally in combination with a reduced space velocity. In such a case, preferred feed hydrocracking conditions thus include a temperature of 300-550° C., a pressure of 300-5000 kPa gauge and a Weight Hourly Space Velocity of 0.1-10 h−1. More preferred feed hydrocracking conditions include a temperature of 300-450° C., a pressure of 300-5000 kPa gauge and a Weight Hourly Space Velocity of 0.1-10 h−1. Even more preferred FHC conditions optimized to the ring-opening of aromatic hydrocarbons include a temperature of 300-400° C., preferably a temperature of 350-450° C., more preferably 375-450° C., a pressure of 600-3000 kPa gauge and a Weight Hourly Space Velocity of 0.2-2 h−1.
The "aromatic ring opening unit" refers to a refinery unit wherein the aromatic ring opening process is performed. Aromatic ring opening is a specific hydrocracking process that is particularly suitable for converting a feed that is relatively rich in aromatic hydrocarbon having a boiling point in the kerosene and gasoil boiling point range to produce LPG and, depending on the process conditions, a light-distillate (ARO-derived gasoline). Such an aromatic ring opening process (ARO process) is for instance described in U.S. Pat. Nos. 3,256,176 and 4,789,457. Such processes may comprise of either a single fixed bed catalytic reactor or two such reactors in series together with one or more fractionation units to separate desired products from unconverted material and may also incorporate the ability to recycle unconverted material to one or both of the reactors. Reactors may be operated at a temperature of 200-600° C., preferably 300-400° C., a pressure of 3-35 MPa, preferably 5 to 20 MPa together with 5-20 wt-% of hydrogen (in relation to the hydrocarbon feedstock), wherein said hydrogen may flow co-current with the hydrocarbon feedstock or counter current to the direction of flow of the hydrocarbon feedstock, in the presence of a dual functional catalyst active for both hydrogenation-dehydrogenation and ring cleavage, wherein said aromatic ring saturation and ring cleavage may be performed. Catalysts used in such processes comprise one or more elements selected from the group consisting of Pd, Rh, Ru, Ir, Os, Cu, Co, Ni, Pt, Fe, Zn, Ga, In, Mo, W and V in metallic or metal sulphide form supported on an acidic solid such as alumina, silica, alumina-silica and zeolites. In this respect, it is to be noted that the term "supported on" as used herein includes any conventional way to provide a catalyst which combines one or more elements with a catalytic support. A further aromatic ring opening process (ARO process) is described in U.S. Pat. No. 7,513,988. Accordingly, the ARO process may comprise aromatic ring saturation at a temperature of 100-500° C., preferably 200-500° C. and more preferably 300-500° C., a pressure of 2-10 MPa together with 5-30 wt-%, preferably 10-30 wt-% of hydrogen (in relation to the hydrocarbon feedstock) in the presence of an aromatic hydrogenation catalyst and ring cleavage at a temperature of 200-600° C., preferably 300-400° C., a pressure of 1-12 MPa together with 5-20 wt-% of hydrogen (in relation to the hydrocarbon feedstock) in the presence of a ring cleavage catalyst, wherein said aromatic ring saturation and ring cleavage may be performed in one reactor or in two consecutive reactors. The aromatic hydrogenation catalyst may be a conventional hydrogenation/hydrotreating catalyst such as a catalyst comprising a mixture of Ni, W and Mo on a refractory support, typically alumina. The ring cleavage catalyst comprises a transition metal or metal sulphide component and a support. Preferably the catalyst comprises one or more elements selected from the group consisting of Pd, Rh, Ru, Ir, Os, Cu, Co, Ni, Pt, Fe, Zn, Ga, In, Mo, W and V in metallic or metal sulphide form supported on an acidic solid such as alumina, silica, alumina-silica and zeolites. By adapting either single or in combination the catalyst composition, operating temperature, operating space velocity and/or hydrogen partial pressure, the process can be steered towards full saturation and subsequent cleavage of all rings or towards keeping one aromatic ring unsaturated and subsequent cleavage of all but one ring. In the latter case, the ARO process produces a light-distillate ("ARO-gasoline") which is relatively rich in hydrocarbon compounds having one aromatic ring.
As used herein, the term "dearomatization unit" relates to a refinery unit for the separation of aromatic hydrocarbons, such as BTX, from a mixed hydrocarbon feed. Such dearomatization processes are described in Folkins (2000) Benzene, Ullmann's Encyclopedia of Industrial Chemistry. Accordingly, processes exist to separate a mixed hydrocarbon stream into a first stream that is enriched for aromatics and a second stream that is enriched for paraffins and naphthenes. A preferred method to separate aromatic hydrocarbons from a mixture of aromatic and aliphatic hydrocarbons is solvent extraction; see e.g. WO 2012135111 A2. The preferred solvents used in aromatic solvent extraction are sulfolane, tetraethylene glycol and N-methylpyrolidone which are commonly used solvents in commercial aromatics extraction processes. These species are often used in combination with other solvents or other chemicals (sometimes called co-solvents) such as water and/or alcohols. Non-nitrogen containing solvents such as sulfolane are particularly preferred. Commercially applied dearomatization processes are less preferred for the dearomatization of hydrocarbon mixtures having a boiling point range that exceeds 250° C., preferably 200° C., as the boiling point of the solvent used in such solvent extraction needs to be lower than the boiling point of the aromatic compounds to be extracted. Solvent extraction of heavy aromatics is described in the art; see e.g. U.S. Pat. No. 5,880,325. Alternatively, other known methods than solvent extraction, such as molecular sieve separation or separation based on boiling point, can be applied for the separation of heavy aromatics in a dearomatization process.
A process to separate a mixed hydrocarbon stream into a stream comprising predominantly paraffins and a second stream comprising predominantly aromatics and naphthenes comprises processing said mixed hydrocarbon stream in a solvent extraction unit comprising three main hydrocarbon processing columns: solvent extraction column, stripper column and extract column. Conventional solvents selective for the extraction of aromatics are also selective for dissolving light naphthenic and to a lesser extent light paraffinic species hence the stream exiting the base of the solvent extraction column comprises solvent together with dissolved aromatic, naphthenic and light paraffinic species. The stream exiting the top of the solvent extraction column (often termed the raffinate stream) comprises the relatively insoluble, with respect to the chosen solvent) paraffinic species. The stream exiting the base of the solvent extraction column is then subjected, in a distillation column, to evaporative stripping in which species are separated on the basis of their relative volatility in the presence of the solvent. In the presence of a solvent, light paraffinic species have higher relative volatilities than naphthenic species and especially aromatic species with the same number of carbon atoms, hence the majority of light paraffinic species may be concentrated in the overhead stream from the evaporative stripping column. This stream may be combined with the raffinate stream from the solvent extraction column or collected as a separate light hydrocarbon stream. Due to their relatively low volatility the majority of the naphthenic and especially aromatic species are retained in the combined solvent and dissolved hydrocarbon stream exiting the base of this column. In the final hydrocarbon processing column of the extraction unit, the solvent is separated from the dissolved hydrocarbon species by distillation. In this step the solvent, which has a relatively high boiling point, is recovered as the base stream from the column whilst the dissolved hydrocarbons, comprising mainly aromatics and naphthenic species, are recovered as the vapour stream exiting the top of the column. This latter stream is often termed the extract.
The process of the present invention may require removal of sulfur from certain crude oil fractions to prevent catalyst deactivation in downstream refinery processes, such as catalytic reforming or fluid catalytic cracking. Such a hydrodesulfurization process is performed in a "HDS unit" or "hydrotreater"; see Alfke (2007) loc. cit. Generally, the hydrodesulfurization reaction takes place in a fixed-bed reactor at elevated temperatures of 200-425° C., preferably of 300-400° C. and elevated pressures of 1-20 MPa gauge, preferably 1-13 MPa gauge in the presence of a catalyst comprising elements selected from the group consisting of Ni, Mo, Co, W and Pt, with or without promoters, supported on alumina, wherein the catalyst is in a sulfide form.
In a further embodiment, the process further comprises a hydrodealkylation step wherein the BTX (or only the toluene and xylenes fraction of said BTX produced) is contacted with hydrogen under conditions suitable to produce a hydrodealkylation product stream comprising benzene and fuel gas.
The process step for producing benzene from BTX may include a step wherein the benzene comprised in the hydrocracking product stream is separated from the toluene and xylenes before hydrodealkylation. The advantage of this separation step is that the capacity of the hydrodealkylation reactor is increased. The benzene can be separated from the BTX stream by conventional distillation.
Processes for hydrodealkylation of hydrocarbon mixtures comprising C6-C9 aromatic hydrocarbons are well known in the art and include thermal hydrodealkylation and catalytic hydrodealkylation; see e.g. WO 2010/102712 A2. Catalytic hydrodealkylation is preferred as this hydrodealkylation process generally has a higher selectivity towards benzene than thermal hydrodealkylation. Preferably catalytic hydrodealkylation is employed, wherein the hydrodealkylation catalyst is selected from the group consisting of supported chromium oxide catalyst, supported molybdenum oxide catalyst, platinum on silica or alumina and platinum oxide on silica or alumina.
The process conditions useful for hydrodealkylation, also described herein as "hydrodealkylation conditions", can be easily determined by the person skilled in the art. The process conditions used for thermal hydrodealkylation are for instance described in DE 1668719 A1 and include a temperature of 600-800° C., a pressure of 3-10 MPa gauge and a reaction time of 15-45 seconds. The process conditions used for the preferred catalytic hydrodealkylation are described in WO 2010/102712 A2 and preferably include a temperature of 500-650° C., a pressure of 3.5-8 MPa gauge, preferably of 3.5-7 MPa gauge and a Weight Hourly Space Velocity of 0.5-2 h−1. The hydrodealkylation product stream is typically separated into a liquid stream (containing benzene and other aromatics species) and a gas stream (containing hydrogen, H2S, methane and other low boiling point hydrocarbons) by a combination of cooling and distillation. The liquid stream may be further separated, by distillation, into a benzene stream, a C7 to C9 aromatics stream and optionally a middle-distillate stream that is relatively rich in aromatics. The C7 to C9 aromatic stream may be fed back to reactor section as a recycle to increase overall conversion and benzene yield. The aromatic stream which contains polyaromatic species such as biphenyl, is preferably not recycled to the reactor but may be exported as a separate product stream and recycled to the integrated process as middle-distillate ("middle-distillate produced by hydrodealkylation"). The gas stream contains significant quantities of hydrogen may be recycled back the hydrodealkylation unit via a recycle gas compressor or to any other refinery that uses hydrogen as a feed. A recycle gas purge may be used to control the concentrations of methane and H2S in the reactor feed.
As used herein, the term "gas separation unit" relates to the refinery unit that separates different compounds comprised in the gases produced by the crude distillation unit and/or refinery unit-derived gases. Compounds that may be separated to separate streams in the gas separation unit comprise ethane, propane, butanes, hydrogen and fuel gas mainly comprising methane. Any conventional method suitable for the separation of said gases may be employed. Accordingly, the gases may be subjected to multiple compression stages wherein acid gases such as CO2 and H2S may be removed between compression stages. In a following step, the gases produced may be partially condensed over stages of a cascade refrigeration system to about where only the hydrogen remains in the gaseous phase. The different hydrocarbon compounds may subsequently be separated by distillation.
A process for the conversion of alkanes to olefins involves "steam cracking" or "pyrolysis". As used herein, the term "steam cracking" relates to a petrochemical process in which saturated hydrocarbons are broken down into smaller, often unsaturated, hydrocarbons such as ethylene and propylene. In steam cracking gaseous hydrocarbon feeds like ethane, propane and butanes, or mixtures thereof, (gas cracking) or liquid hydrocarbon feeds like naphtha or gasoil (liquid cracking) is diluted with steam and briefly heated in a furnace without the presence of oxygen. Typically, the reaction temperature is 750-900° C., but the reaction is only allowed to take place very briefly, usually with residence times of 50-1000 milliseconds. Preferably, a relatively low process pressure is to be selected of atmospheric up to 175 kPa gauge. Preferably, the hydrocarbon compounds ethane, propane and butanes are separately cracked in accordingly specialized furnaces to ensure cracking at optimal conditions. After the cracking temperature has been reached, the gas is quickly quenched to stop the reaction in a transfer line heat exchanger or inside a quenching header using quench oil. Steam cracking results in the slow deposition of coke, a form of carbon, on the reactor walls. Decoking requires the furnace to be isolated from the process and then a flow of steam or a steam/air mixture is passed through the furnace coils. This converts the hard solid carbon layer to carbon monoxide and carbon dioxide. Once this reaction is complete, the furnace is returned to service. The products produced by steam cracking depend on the composition of the feed, the hydrocarbon to steam ratio and on the cracking temperature and furnace residence time. Light hydrocarbon feeds such as ethane, propane, butane or light naphtha give product streams rich in the lighter polymer grade olefins, including ethylene, propylene, and butadiene. Heavier hydrocarbon (full range and heavy naphtha and gas oil fractions) also give products rich in aromatic hydrocarbons.
To separate the different hydrocarbon compounds produced by steam cracking the cracked gas is subjected to a fractionation unit. Such fractionation units are well known in the art and may comprise a so-called gasoline fractionator where the heavy-distillate ("carbon black oil") and the middle-distillate ("cracked distillate") are separated from the light-distillate and the gases. In the subsequent optional quench tower, most of the light-distillate produced by steam cracking ("pyrolysis gasoline" or "pygas") may be separated from the gases by condensing the light-distillate. Subsequently, the gases may be subjected to multiple compression stages wherein the remainder of the light distillate may be separated from the gases between the compression stages. Also acid gases (CO2 and H2S) may be removed between compression stages. In a following step, the gases produced by pyrolysis may be partially condensed over stages of a cascade refrigeration system to about where only the hydrogen remains in the gaseous phase. The different hydrocarbon compounds may subsequently be separated by simple distillation, wherein the ethylene, propylene and C4 olefins are the most important high-value chemicals produced by steam cracking. The methane produced by steam cracking is generally used as fuel gas, the hydrogen may be separated and recycled to processes that consume hydrogen, such as hydrocracking processes. The acetylene produced by steam cracking preferably is selectively hydrogenated to ethylene. The alkanes comprised in the cracked gas may be recycled to the process for olefins synthesis.
The term "propane dehydrogenation unit" as used herein relates to a petrochemical process unit wherein a propane feedstream is converted into a product comprising propylene and hydrogen. Accordingly, the term "butane dehydrogenation unit" relates to a process unit for converting a butane feedstream into C4 olefins. Together, processes for the dehydrogenation of lower alkanes such as propane and butanes are described as lower alkane dehydrogenation process. Processes for the dehydrogenation of lower alkanes are well-known in the art and include oxidative dehydrogenation processes and non-oxidative dehydrogenation processes. In an oxidative dehydrogenation process, the process heat is provided by partial oxidation of the lower alkane(s) in the feed. In a non-oxidative dehydrogenation process, which is preferred in the context of the present invention, the process heat for the endothermic dehydrogenation reaction is provided by external heat sources such as hot flue gases obtained by burning of fuel gas or steam. In a non-oxidative dehydrogenation process the process conditions generally comprise a temperature of 540-700° C. and an absolute pressure of 25-500 kPa. For instance, the UOP Oleflex process allows for the dehydrogenation of propane to form propylene and of (iso)butane to form (iso)butylene (or mixtures thereof) in the presence of a catalyst containing platinum supported on alumina in a moving bed reactor; see e.g. U.S. Pat. No. 4,827,072. The Uhde STAR process allows for the dehydrogenation of propane to form propylene or of butane to form butylene in the presence of a promoted platinum catalyst supported on a zinc-alumina spinel; see e.g. U.S. Pat. No. 4,926,005. The STAR process has been recently improved by applying the principle of oxydehydrogenation. In a secondary adiabatic zone in the reactor part of the hydrogen from the intermediate product is selectively converted with added oxygen to form water. This shifts the thermodynamic equilibrium to higher conversion and achieves a higher yield. Also the external heat required for the endothermic dehydrogenation reaction is partly supplied by the exothermic hydrogen conversion. The Lummus Catofin process employs a number of fixed bed reactors operating on a cyclical basis. The catalyst is activated alumina impregnated with 18-20 wt-% chromium; see e.g. EP 0 192 059 A1 and GB 2 162 082 A. The Catofin process has the advantage that it is robust and capable of handling impurities which would poison a platinum catalyst. The products produced by a butane dehydrogenation process depends on the nature of the butane feed and the butane dehydrogenation process used. Also the Catofin process allows for the dehydrogenation of butane to form butylene; see e.g. U.S. Pat. No. 7,622,623.

This patent is subject to a terminal disclaimer.

Method for cracking a hydrocarbon feedstock in a steam cracker unit


A cosmetic cleansing article is provided which includes an effervescent cleanser composition held within a sachet having at least one water permeable wall. The effervescent composition is an intimate mixture of an acid material such as citric acid and an alkaline material such as sodium bicarbonate. Water contact causes the combination to effervesce. The powdered mixture of alkaline/acid materials is storage stabilized against premature effervescent action by dispersing therewithin plant solids.

1. Field of the Invention
The invention concerns an effervescent foaming composition in a storage stabilized dry form, the composition preferably being applied for body cleansing and delivered within a water permeable sachet.
2. The Related Art
Classically the process of cleansing skin or other substrates has employed a surfactant composition. Sometimes an implement has joined the composition. Implements such as sachets serve a multi-purpose. One function is as a delivery package for the surfactant. Sachets may also assist in generating foam. They also function as an abrasive assisting in the cleansing function.
An early example of cleansing pad technology is found in U.S. Pat. No. 1,808,834 (Busch Sr.). A fabric pouch is disclosed surrounding a cleansing composition mainly consisting of calcium and sodium carbonate.
U.S. Pat. No. 4,234,442 (Cornelissens) describes a sachet which can consist of a water permeable material filled with an acidic and an alkaline constituent. Adipic, succinic and glutaric acids exemplify the acidic constituent. Sodium bicarbonate and carbonate represent the alkaline ingredient.
U.S. Pat. No. 4,272,393 (Gergely) describes a cleaning article formed of a porous flexible substrate, especially a cellulosic paper, impregnated with detergent and a gas-generating system. The latter is formed by separating an acidic component such as citric acid from a basic component such as sodium carbonate in two separate areas of the substrate.
U.S. Pat. No. 4,515,703 (Haq), U.S. Pat. No. 4,600,620 (Lloyd et al.) and U.S. Pat. No. 4,603,069 (Haq et al.) all describe wiping articles impregnated with surfactant. These do not contain any effervescent ingredients.
WO 97/43366 (Askew et al.) reports an effervescent system to improve dispensability of granular laundry detergent powders into wash water of automatic washing machines. Citric acid and bicarbonate combinations are employed to generate effervescence.
WO 99/48469 (Yagnik et al.) discloses powdered compositions some of which may be delivered via a tea bag. These compositions are formulated with an exothermic ingredient, a pH adjusting agent such as citric acid, optionally sodium bicarbonate for an effervescent effect and an aromatic ingredient for fragrance.
Common to those of the aforementioned systems employing effervescent anhydrous powders is the need to maintain them in a dry state under storage conditions. Seepage of atmospheric moisture into the powders will prematurely activate effervescence.
Accordingly, it is an object of the present invention to stabilize against premature activation a powdered effervescent cleanser composition.
Another object of the present invention is to provide a powdered system for effervescing wherein the powders are stabilized against caking.
Yet another object of the present invention is to provide a cleansing article such as a sachet containing an effervescent system which upon being activated by water generates carbon dioxide to enhance the lathering of cleanser components.
Still a further object of the invention is to provide a cleansing article which imparts a pleasant sensory feel to skin during and after use.
It is to be noted that the subsequently described invention is broader than the objects or technical problems it is directed to solve.
A cosmetic article is provided for cleansing body surfaces, the article including:
a sachet having at least one water permeable wall, the sachet being sealed along its perimeter; and
an effervescent cleanser composition in the form of an anhydrous dry solid being positioned within the sachet, the composition including:
(i) from about 1 to about 80% of an alkaline material;
(ii) from about 0.5 to about 80% of an acid material; and
(iii) from about 0.1 to about 80% of dried plant solids.
Also provided is a method for cleansing skin involving wetting with water a cosmetic article containing the effervescent composition delineated above, generating foam from the article and contacting skin surfaces with the generated foam, particularly in the context of bathing.
Now it has been found that dried plant solids can be interspersed with a powdered composition of alkaline material and acid material to act as a stabilizing agent against premature activation of effervescence. Plant solids of almost any description can be employed. These solids will be in particle form having sizes ranging from about 1 mm to about 40 mm in length, and of comparable width. Preferably, the solids will have particle sizes ranging from about 5 mm to about 25 mm, more preferably from about 10 mm to about 15 mm. So long as they are dried, most any portion of a plant may be employed including stems, flowers and leaves. Leaves are most desirable. Amounts of the plant solids will range from about 0.1 to about 80%, preferably from 5 to 50%, optimally from about 10 to about 30% by weight.
Non-limiting examples of plant solids may include herbs, teas (e.g. green, black and oolong tea) and potpourri. Among suitable plant solids are those derived from the leaves, flowers, stems and roots of such botanicals as wintergreen, bay (leaves) cocoa, eucalyptus, cotton, biti, lemongrass, lily, spanish moss, rosemary, parsley, tarragon, angelica, basil, hops, oregano, thyme, zatar, ginseng, willow, poplar, dandelion, comfrey and combinations thereof. These solids need not be fragrance emitting, and indeed it is preferred to add aroma chemicals separate from the plant solids. In a preferred embodiment, the aroma chemicals and fragrances are sprayed onto a solid substrate, preferably a polysaccharide, and the mixture then incorporated with the alkaline and acid powdered materials.
Cosmetic wiping articles of the present invention when contacted with water billow to many times (more than 10 but often more than 40 times) their dry size when activated by water. The effervescent cleansing system exudes copious amounts of lather. A plumped xe2x80x9cpillowxe2x80x9d arises from the effervescent action. By careful control of the acidic and alkaline components, a squeaky clean rinsed feeling is felt on a user""s skin.
An important component of compositions within the sachet is that of an acidic material. Suitable for this purpose are any acids present in dry solid form. Especially appropriate are C2-C20 organic mono- and poly-carboxylic acids and especially alpha- and beta-hydroxycarboxylic acids; C2-C20 organophosphorus acids such as phytic acid; C2-C20 organosulfur acids such as toluene sulfonic acid; and peroxides such as hydrogen peroxide. Typical hydroxycarboxylic acids include adipic, glutaric, succinic, tartaric, malic, maleic, lactic, salicylic and citric acids as well as acid forming lactones such as gluconolactone and glucarolactone. Most preferred is citric acid. Also suitable as acid material may be encapsulated acids. Typical encapsulating material may include water soluble synthetic or natural polymers such as polyacrylates (e.g. encapsulating polyacrylic acid), cellulosic gums, polyurethane and polyoxyalkylene polymers. By the term xe2x80x9cacidxe2x80x9d is meant any substance which when dissolved in deionized water at 1% concentration will have a pH of less than 7, preferably less than 6.5, optimally less than 5. These acids preferably at 25xc2x0 C. are in solid form, i.e. having melting points no less than 25xc2x0 C. Concentrations of the acid should range from about 0.5 to about 80%, preferably from about 10 to about 65%, optimally from about 20 to about 45% by weight of the total composition.
Another important component of compositions within the sachet is that of an alkaline material. The alkaline material is a substance which can generate a gas such as carbon dioxide, nitrogen or oxygen, i.e. effervesce, when contacted with water and the acidic material. Suitable alkaline materials are anhydrous salts of carbonates and bicarbonates, alkaline peroxides (e.g. sodium perborate and sodium percarbonate) and azides (e.g. sodium azide). Preferably the alkaline material is sodium or potassium bicarbonate. Amounts of the alkaline material may range from about 1 to about 80%, preferably from about 5 to about 49%, more preferably from about 15 to about 40%, optimally from about 25 to about 35% by weight of the total composition.
By the term xe2x80x9canhydrousxe2x80x9d is meant the presence of no more than 5%, preferably no more than 3.5% and optimally no more than 1% water by weight of the total composition. Water of hydration is not considered to be water for purposes of the anhydrous definition. However, it is preferred to minimize, preferably to eliminate any water of hydration.
Advantageously the combined amount of acidic and alkaline materials will be at least about 1.5%, preferably from about 40 to about 95%, optimally from about 60 to about 80% by weight of the total composition.
Advantageously but not necessarily compositions can include a surfactant, preferably, a dry surfactant solid at 20xc2x0 C. Most suitable for the present invention is sodium cocoyl isethionate. Other useful surfactants include sodium methyl cocoyl taurate and sodium lauryl sulfate. Surfactants may be of the anionic, cationic, nonionic, amphoteric, zwitterionic varieties and combinations thereof. Amounts of the dry surfactant may range from about 0.1 to about 30%, preferably from about 1 to about 30%, optimally from about 8 to about 15% by weight of the total composition.
A variety of skin benefit agents may be included to improve afterfeel properties. Advantageously these substances will be available as anhydrous dry powders. Alternatively these substances may be liquids deposited upon or into a powdered substrate (e.g. sodium bicarbonate or zeolite) to achieve a resultant dry flowing powder. Within the skin benefit agent scope are several categories of materials. These include emollients, antiaging actives, antibacterials and fungicides, skin lighteners, sunscreens and combinations thereof. Amounts of the skin benefit agents may range from about 0.001 to about 30%, preferably from about 0.1 to about 20%, more preferably from about 0.5 to about 10%, optimally between about 1 and about 5% by weight of the total composition.
Emollients may be in the form of natural or synthetic esters, silicone oils, hydrocarbons, starches, fatty acids and mixtures thereof. Typically the emollient may range in concentration from about 0.1 to about 35% by weight of the total composition.
Silicone oils may be divided into the volatile and nonvolatile variety. The term xe2x80x9cvolatilexe2x80x9d as used herein refers to those materials which have a measurable vapor pressure at ambient temperature. Volatile silicone oils are preferably chosen from cyclic or linear polydimethylsiloxanes containing from 3 to 9, preferably from 4 to 5, silicon atoms.
Linear volatile silicone materials generally have viscosities less than about 5 centistokes at 25xc2x0 C. while cyclic materials typically have viscosities of less than about 10 centistokes.
Nonvolatile silicone oils useful as an emollient material include polyalkyl siloxanes, polyalkylaryl siloxanes and polyether siloxane copolymers. The essentially non-volatile polyalkyl siloxanes useful herein include, for example, polydimethyl siloxanes with viscosities of from about 5 to about 100,000 centistokes at 25xc2x0 C. Among the preferred non-volatile emollients useful in the present compositions are the polydimethyl siloxanes having viscosities from about 10 to about 400 centistokes at 25xc2x0 C.
Among the ester emollients are:
(1) Alkenyl or alkyl esters of fatty acids having 10 to 20 carbon atoms. Examples thereof include isoarachidyl neopentanoate, isononyl isonanonoate, oleyl myristate, oleyl stearate, and oleyl oleate.
(2) Ether-esters such as fatty acid esters of ethoxylated fatty alcohols.
(3) Polyhydric alcohol esters. Ethylene glycol mono and di-fatty acid ester, diethylene glycol mono- and di-fatty acid esters, polyethylene glycol (200-6000) mono- and di-fatty acid esters, polypropylene glycol 2000 monooleate, polypropylene glycol 2000 monostearate, ethoxylated propylene glycol monostearate, glyceryl mono- and di-fatty acid esters, polyglycerol poly-fatty esters, ethoxylated glyceryl monostearate, 1,3-butylene glycol monostearate, 1,3-butylene glycol distearate, polyoxyethylene polyol fatty acid ester, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters are satisfactory polyhydric alcohol esters.
(4) Wax esters such as beeswax, spermaceti, myristyl myristate, stearyl stearate and arachidyl behenate.
(5) Sterols esters, of which cholesterol fatty acid esters are examples thereof.
(6) Triglycerides such as sunflower seed oil, maleated sunflower seed oil, borage seed oil and safflower oil.
Hydrocarbons suitable as emollients include petrolatum, mineral oil, isoparaffins and hydrocarbon waxes such as polyethylene.
Starches are also suitable emollients. Typical of this class is tapioca and arabinogalactan.
Fatty acids may also be suitable as emollients. The fatty acids normally have from 10 to 30 carbon atoms. Illustrative of this category are pelargonic, lauric, myristic, palmitic, stearic, isostearic, hydroxystearic, oleic, linoleic, riconleic, arachidic, behenic and erucic acids.
Antiaging actives are also useful as skin benefit agents. Included within this category are vitamins, retinoids and combinations thereof. Amounts of these materials may range from about 0.001 to about 20% by weight of the total composition. Suitable vitamins include ascorbic acid, Vitamin B6, Vitamin B12, tocopherol as well as salts and C1-C20 esters thereof. Suitable retinoids include retinoic acid as well as its C1-C22 esters and salts, retinol and C1-C22 fatty esters of retinol including retinyl linoleate.
Another class of antiaging actives are the alpha- and beta-hydroxycarboxylic acids and salts thereof. Representative of this group are glycolic acid, lactic acid, malic acid, hydroxyoctanoic acid and mixtures of these as well as their salts. Suitable salts are the alkalimetal, ammonium and C1-C10 alkanol ammonium salts.
Antibacterials and fungicidals may also be included as skin benefit agents. Representative of these categories are triclosan, tricloban, hexetidene, chlorhexadene, gluconates, zinc salts (e.g. zinc citrate and zinc phenolsulfonate) and combinations thereof.
Skin lighteners may also be included under the skin benefit agents. Typical of this category are niacinamide, kojic acid, arbutin, vanillin, ferulic acid and esters thereof, resorcinol, hydroquinone, placental extract and combinations thereof.
Sunscreens may also be included as skin benefit agents. Particularly preferred are such materials as ethylhexyl p-methoxycinnamate, available as Parsol(copyright) MCX, and benzophenone-3, also known as Oxybenzone. Inorganic sunscreen actives may be employed such as microfine titanium dioxide, polyethylene and various other polymers. Amounts of the sunscreen agents will generally range from 0.1 to 30%, preferably from 2 to 20%, optimally from 4 to 10% by weight.
Adjunct functional agents may also be incorporated into compositions of the present invention. These include electrolytes, thickeners and mixtures thereof. Amounts of these substances may range from about 0.1 to about 20%, preferably from about 0.3 to about 10%, optimally between about 0.5 and about 5% by weight of the total composition.
Electrolytes may be selected from alkali, alkaline earth or ammonium salts of phosphates, silicates, halides, sulphates and mixtures thereof. Typical phosphates are potassium polymetaphosphate, sodium tripolyphosphate, sodium tetrapyrophosphate, sodium or potassium pyrophosphate and sodium hexametaphosphate. Most preferred is potassium polymetaphosphate available as Lipothix 100B(copyright) which is a 70:30 mixture of potassium polymetaphosphate and sodium bicarbonate, available from Lipo Chemicals, Inc., Paterson, N.J. Preferred sulphates are the magnesium sulphates.
Thickeners which may improve afterfeel properties on skin include inorganic or organic substances. A particularly preferred inorganic thickener is sodium magnesium silicate commercially available as Optigel SH(copyright). Organic thickeners include alginic acid as well as sodium and calcium alginates, sodium carboxymethyl cellulose, hydroxypropyl methylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose and combinations thereof. Most preferred is alginic acid commercially available as Kelacid(copyright) from Sud-Chemie Rheologicals, Louisville, Ky. Alginic acid is highly effective at removing the slimy feel associated with deposits of alkaline material which are not fully rinsed away from the skin. Amounts of the thickener may range from about 0.1 to about 20%.
Polysaccharides useful in this invention are dry solid anhydrous substances such as sorbitol, sugars, (such as trehalose) starches, modified starches (e.g. aluminum octenyl succinate) and mixtures thereof. Most preferred is sorbitol.
Deposition aids may also be incorporated in compositions of the present invention. These assist in depositing skin benefit agents onto the skin surface. Particularly effective are cationic monomers and polymers for this purpose. Most preferred for purposes of this invention are cationic guar gums such as Jaguar C13S(copyright) which is guar hydroxypropyltrimonium chloride. Amounts of the deposition aid may range from about 0.01 to about 1%, preferably from about 0.05 to about 0.5%, optimally from about 0.1 about 0.3% by weight.
Advantageously an emotive agent such as a fragrance and/or botanical extract are included with the effervescent cleansing composition. Fragrances and botanicals are often liquids. For this reason it is necessary to uniformly distribute and allow absorption of liquid components into the solid powder. One method of best achieving this is to spray these liquids onto the solids. Amounts of the fragrance and/or botanicals combined may be at levels from 0.1 to 3%, preferably from 0.5 to 2%, optimally from 0.8 to 1.5% by weight of the total composition.
The terms xe2x80x9cfragrancexe2x80x9d and xe2x80x9cbotanical extractxe2x80x9d are defined as mixtures of odoriferous components, optionally mixed with a suitable solvent diluent or carrier, which is employed to impart a desired odor. Particular preferred odoriferous components are cyclic and acyclic terpenes and terpenoids. These materials are based upon isoprene repeating units. Examples include alpha and beta pinene, myrcene, geranyl alcohol and acetate, camphene, dl-limonene, alpha and beta phellandrene, tricyclene, terpinolene, allocimmane, geraniol, nerol, linanool, dihydrolinanool, citral, ionone, methyl ionone, citronellol, citronellal, alpha terpineol, beta terpineol, alpha fenchol, borneol, isoborneol, camphor, terpinen-1-ol, terpin-4ol, dihydroterpineol, methyl chavicol, anethole, 1,4 and 1,8 cineole, geranyl nitrile, isobornyl acetate, linalyl acetate, caryophyllene, alpha cedrene, guaiol, patchouli alcohol, alpha and beta santalol and mixtures thereof. Botanical extracts of particular use in the present invention include those extracted from yarrow, chamomile, jasmine, lavender, horse chestnut, sage, thyme, yucca, coltsfoot and mixtures thereof.
Preservatives can desirably be incorporated into the cosmetic compositions of this invention to protect against the growth of potentially harmful microorganisms. Particularly preferred preservatives are phenoxyethanol, methyl paraben, propyl paraben, imidazolidinyl urea, sodium dehydroacetate and benzyl alcohol. The preservatives should be selected having regard for the sue of the composition and possible incompatibilities between the preservatives and other ingredients in the emulsion. Preservatives are preferably employed in amounts ranging from 0.01% to 2% by weight of the composition.
Colorants may also be included in compositions of the present invention. These substances may range from about 0.05 to about 5%, preferably between 0.1 and 3% by weight.
Effervescent cleansing compositions of this invention will be placed within a sachet. Preferably the sachet is constructed from a first and second substrate sheet. At least one of the sheets must be water permeable, most preferably both sheets should have water permeability. For definitional purposes, first and second sheets can be folded-over panels of a single unitary sheet. Suitable materials for forming sheets may be rayon, polyester, polyethylene, polypropylene, cotton or any combination thereof. These sheets may be woven or non-woven. Most preferred is a non-woven rayon. Cellulosic paper fiber substrates are best not employed because of their insufficient wet-strength although they may be blended with other fibers referenced above; it is important that the substrate sheets are not readily torn open through consumer rubbing of the article. Unlike laundry sachet articles, sachets of the present invention should not rupture to allow dispersion of their granular contents into wash water. Rather it is intended for all cleanser composition components to exit by dissolution through the permeable walls of the sachet. Advantageously at least one of the sheets should be sufficiently translucent to allow viewing from outside of the ingredients. A calendered pattern helps achieve a translucent panel while still retaining strength and water permeability. Sachets may have any geometric shape including square, round, oval and tetrahedral configurations.
Skin surfaces against which articles of the present invention are useful include face, body, scalp, axilla and even legs/feet. When the article is a foot cleanser, it would be advantageous for the sachet on one of its sides to be coarse while the second of the sheets may be soft and gentle. An abrasive non-woven flexible sheet in a foot cleanser product is useful for rubbing against calluses while the second sheet of the sachet remains smooth.
Articles according to the present invention may be formed in a variety of ways. An illustrative but certainly non-limiting example is as follows. Constituents of the effervescent cleansing composition other than the plant solids are placed into a dry mill or similar apparatus and blended until a uniformly distributed powder results. Liquid fragrance is sprayed onto a polysaccharide powder which in turn is added to the dry mill with concurrent agitation of the powdered composition. Sachets are formed of water permeable rayon/polyester walls in the form of a tetrahedron having three of its sides sealed, leaving an open top side. Plant solids are then added to the sachet through the open side. Subsequently, the effervescent composition is charged into the sachet and the latter sealed shut by heat bonding.
Ultrasonic welding may be employed as an alternative to heat-sealing. Thread stitching, glue application or other closure mechanisms may also be utilized.
Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material are to be understood as modified by the word xe2x80x9caboutxe2x80x9d.
The term xe2x80x9ccomprisingxe2x80x9d is meant not to be limiting to any subsequently stated elements but rather to encompass non-specified elements of major or minor functional importance. In other words the listed steps, elements or options need not be exhaustive.
All measurements referred to herein are made at 25xc2x0 C. unless otherwise specified. All publications, patent applications and issued patents mentioned herein are hereby incorporated in their entirety by reference. Citation of any reference is not an admission regarding any determination as to its availability as prior art to the claimed invention.

Cosmetic effervescent cleansing compositions

Unilever Home and Personal Care USA, division of Conopco, Inc.