Structural and catalytic activity of V2O5-supported on AlPO4 catalysts

A series of AlPO4-V2O5 (APV) systems with various vanadia amounts 1-30 mol% were prepared by the impregnation method and calcinated at 400 and 600degreesC for 4 h. The catalysts were characterized by TG/DTG, DSC, IR spectroscopy, XRD, N-2 adsorption, and electrical conductivity measurements. The surface acidity and basicity of the catalysts were studied by the dehydration-dehydrogenation of isopropyl alcohol and the adsorption of pyridine. The catalytic gas phase esterification of acetic acid with ethyl alcohol was carried out at 210degreesC in a flow system at 1 atm using air as a carrier gas. The results showed that the catalysts calcinated at 400degreesC were active and selective towards the formation of ethyl acetate whereas the calcination of samples at 600degreesC led to a drastic reduction in both activity and selectivity. Good correlations were obtained between catalytic activities towards ester formation and acidity of the prepared catalysts.