Catalytic studies were performed in a previously described fixed-bed reactor in upward flow configuration (Figure ). Briefly, 3 g of catalyst were placed in the isothermal zone in the center of the stainless-steel reactor (ID = 1.6 cm, length = 20 cm). The catalyst powders were pressed (8 tons), crushed, and sieved to 100-200 micron particles to avoid mass transfer limitations (Figure ). Neat acetone was fed into the reactor with an HPLC pump, and the reaction was performed at 200-300 °C and 75 bar to maintain liquid/supercritical conditions. The outlet of the reaction feed was continuously mixed with a standard solution of 1,4-dioxane (1.15 mol L -1 ) in 1-butanol downstream. The product solution was analyzed via online-gas chromatography (Shimadzu GC-2030, MEGA-5 column, 40-250 °C, 10 K min -1 , H2) equipped with an FID (Figure ). Acetone, mesityl oxide, mesitylene, isophorone, 2-butanone, and 1,3,5-triethylbenzene were calibrated with pure compounds while the other identified products were estimated via the concept of the effective carbon number combined with GC-MS.