Vanadium phosphorus oxide (VPO) catalyst samples with different P/V molar ratios were prepared in mixture of isobutanol and benzyl alcohol, and their catalytic performance for selective oxidation of propane to acrylic acid (AA) and acetic acid (HAc) by lattice oxygen was investigated in a pulse reactor. The results showed that the AA and HAc only formed over the catalyst samples with n (P)/ n (V)>1 0. The proper n (P)/ n (V) is about 1 1, with which the catalyst samples have the best catalytic performance and maximum reversible oxygen storage capacity. It was also found that the ratio of n (AA)/ n (HAc) increased with the increasing of both the reaction temperature and the n (P)/ n (V) in the catalyst. The XRD results indicated that the title reaction is sensitive to the crystal structure and the active phase is (VO) 2P 2O 7.
The selective oxidation of propane over vanadium phosphorus oxide(VPO) catal yst has been investigated by using chromatography in a pulse reactor. The results showed that it is the lattice oxygen that oxidizes propane to form acrylic acid and acetic acid. This mechanism was also supported by TPD and XPS data. It is concluded that the oxidation of propane takes place on the surface of the catalyst according to Mars van Krevelen mechani sm , so that it could be implemented in a circulating fluidized bed(CFB) riser reactor. The re oxidation of VPO catslyst is found to be the rate controlling step in the oxidation reaction.
