Synthesis of CexZr1-xO2/SiO2 supports for chromium oxide catalysts of oxidative dehydrogenation of propane with carbon dioxide

BACKGROUND: Propane dehydrogenation is an alternative way both to produce propylene and to utilize CO2. Because of the high oxygen mobility in cerium-zirconium oxide (CexZr1-xO2), it looks promising as a support for the chromium oxide catalysts of propane dehydrogenation with CO2. Supports of CexZr1-xO2 on mesoporous silica were synthesized in this work to combine the high oxygen mobility of the former and the pore structure of the latter. RESULTS: Two applied synthetic approaches resulted in materials with different structure and properties. The wet impregnated catalysts demonstrated a higher activity and selectivity to propylene. At the same time, they had larger pore size distribution maxima (similar to 9 nm) than the samples prepared by the introduction of metals simultaneously with Si-precursor hydrolysis (similar to 2 nm). For the chromium catalysts with the same support, the catalytic activity decreased with varying chromium loading as follows: 5% Cr > 3% Cr approximate to 7% Cr. For the catalysts with different CexZr1-xO2 supports and equal chromium loading, the activity decreased with x changing as follows: 0.5 > 0.6 > 0.8 for the samples prepared by wet impregnation, and 0.8 approximate to 0.6 > 0.5 for the other synthetic path. CONCLUSIONS: Catalysts were tested in oxidative dehydrogenation of propane with CO2. The wet impregnation approach turned out to be much more promising in terms of catalytic activity and selectivity to propylene in the reaction of propane dehydrogenation with CO2. The selectivity achieved was <= 80% at a 40% conversion. (c) 2023 Society of Chemical Industry (SCI).