Spray dried VCrO/SiO2 micro-spheroidal catalyst for the ammoxidation of p-chlorotoluene

Formulation and shaping of heterogeneous catalysts are vital in the successful industrial application. Here micro-sized vanadium chromium composite oxides catalysts with the spherical shape were prepared via spray drying with colloidal silica as a binder material. The physicochemical properties of catalysts with different Cr/V molar ratios were characterized by XRD, XPS, FT-IR, TPR, and particle size distribution analysis. It was revealed that the addition of Cr inhibited the formation of the crystalline phase V 2 O 5 and decreased the reduction temperature of pentavalent vanadium species, and also resulted in the formation of monoclinic CrVO 4 and a highly dispersed state of vanadia species. VCrO/SiO 2 particles with various Cr/V atomic ratio were studied as catalysts for p -chlorotoluene ammoxidation to p -chlorobenzonitrile, in which the catalyst with Cr/V ratio of 1 exhibited the best catalytic performance. When the Cr/V ratio was less than 1, mixed phases of orthorhombic CrVO 4 and monoclinic Cr 2 V 4 O 13 were formed and resulted in a low catalytic activity. With the increase of Cr/V ratio, the content of monoclinic CrVO 4 in the catalysts increased, resulting in the catalytic activity of the catalysts improved. However, too large an amount of Cr led to the formation of highly oxidizing hexagonal-Cr 2 O 3 phase, which reduced the selectivity of the catalytic reaction. Graphic abstract