Oxidative dehydrogenation of n-butane and 1-butene on undoped and K-doped VOx/Al2O3 catalysts

The oxidative dehydrogenation (OXDH) of n-butane and 1-butene on undoped an d K-doped alumina-supported vanadia catalysts has been studied. The low sel ectivity to OXDH products on alumina-supported vanadia catalysts is a conse quence of the isomerization of olefins (low temperatures) and the formation of carbon oxides (high temperatures) on acid sites. The presence of potass ium results in a decrease of the number of acid sites and a higher selectiv ity to OXDH products from both n-butane and 1-butene. Infrared spectroscopy data of 1-butene adsorbed on the catalysts suggest the presence of differe nt adsorbed species: (i) O-containing species on the undoped catalyst, or ( ii) adsorbed butadiene on K-doped catalyst. A reaction network including pa rallel and consecutive reactions is proposed. (C) 2000 Elsevier Science B.V . All rights reserved.