Cr doped mesoporous silica spheres for propane dehydrogenation in the presence of CO2: Effect of Cr adding time in sol-gel process

CrOX-doped mesoporous silica spheres (Cr/MSS-X) were prepared by adding Cr precursors at different preparation stages using sol-gel method (X = 1, 2, 3) and incipient-wetness impregnation method (X = 4), and their catalytic performances of propane oxidative dehydrogenation were evaluated in the presence of CO2. The results indicate that for the Cr/MSS-X catalysts prepared by sol-gel method, Cr adding time significantly influences the Cr dispersion, surface physic-chemical properties and their catalytic performance. Cr/MSS-2 catalysts obtained by adding Cr precursor after the tetraethyl-orthosilicate (TEOS) show the optimal catalytic activity. Although Cr/MSS-1 also shows good CrOX dispersion, part CrOX wrapped in the center of mesoporous silica spheres presents weaker catalytic activity. In this work, the catalyst preparation method is quite facile and has the potential to be utilized for industrial production.