SURFACE STRUCTURE, PHASE COMPOSITION AND CATALYTIC PROPERTIES OF V-Sb-O/Al2O3 OXIDE SYSTEMS IN THE REACTION OF OXIDATIVE DEHYDROGENATION OF PROPANE

Experimental results of studying the morphology, phase composition, magnetic and catalytic properties of vanadium-antimony-containing aluminum oxide samples in the reaction of oxidative dehydrogenation of propane (ODP) with carbon dioxide are presented. It has been shown that in the X-ray diffraction patterns of vanadium-aluminum and antimony-vanadium-aluminum oxide catalysts with a vanadium content of less than 15 and an antimony content of less than 5 wt.%, respectively, only peaks belonging to γ-Al2O3 are observed. It is assumed that the absence of V2O5 peaks is due to the presence of vanadium oxide in these catalysts in a highly dispersed amorphous state in the form of polymer structures (VOx)n. In the X-ray diffraction patterns of the catalyst with the composition 5%Sb-15%V/Al2O3, peaks characteristic of the Sb2O3 and SbVO4 phases are observed. According to the EPR spectra, vanadium ions in the +4 oxidation state are identified as vanadyl ions VO2+. It has been shown that the introduction of antimony into the composition of a vanadium-aluminum oxide catalyst increases the amount of vanadyl ions VO2+ and its activity in the ODP reaction. It was found that samples of the used γ-Al2O3 carrier are inactive in the ODP reaction and acquire this activity after introducing vanadium into them. The introduction of antimony into vanadium-containing aluminum oxides enhances the catalytic activity and significantly increases their selectivity in the ODP reaction. The thermodynamics of the reactions of formation of vanadium-antimony oxide structures and ODP with their participation have been studied