Propane oxidative dehydrogenation over V-containing mixed oxides derived from decavanadate-exchanged ZnAl-layered double hydroxides prepared by a sol-gel method

摘要

The catalytic properties of ZnAlVO mixed oxides derived from decavanadate-exchanged ZnAl layered double hydroxide (LDH) precursors prepared by a sol-gel method (ZnAlVO-LDHx,y) were investigated in the oxidative dehydrogenation of propane and compared with those of supported catalysts obtained by conventional impregnation of NH4VO3 on ZnO (ZnVO-I,y) and ZnAlO mixed oxide (ZnAlVO-I,y) supports. The effects of composition and calcination time on the catalytic behavior were particularly examined. Higher propane conversions were achieved at higher vanadium content and calcination time of the precursors. The LDH-derived catalysts were the most active ones in all the temperature range studied (300-425 degrees C). The order of activity for propane conversion for the different catalyst families varies as ZnAlVO-LDHx,y ZnAlVO-I ZnVO-I and follows the strength of the Lewis and Bronsted acid sites determined by monitoring of pyridine adsorption by Fourier transform infrared spectroscopy, whereas the propene selectivities are close together in agreement with the similar densities of basic sites determined by CO2-temperature-programmed desorption measurements. It was indeed established that the acidity, rather than the nature of the crystalline phases, the reducibility, or the specific surface area of the samples, governs the catalytic activity. (C) 2017 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.