Enhancement of the Catalytic Performance of NiMoO_4 and Modification of the Kinetic parameters of Oxidative Dehydrogenation of Propane over NiMoO_4/Sb_2O_4 Biphasic Catalyst by Oxygen spillover

摘要

Partial oxidation of propane to propene was investigated over monophasic NiMoO_4 and biphasic NiMoO_4/α-Sb_2O_4 in different proportions in heterogeneous reaction region. The existence of α-Sb_2O_4 in the mixture with NiMoO_4 produces a synergetic effect between the two phases. Selectivity towards propene was maximal with a mass ratio of NiMoO_4/(NiMoO_4+α-Sb_2O_4) close to 0.25. The presence of α-Sb_2O_4 in the mixture with NiMoO_4 modifies the kinetic parameters of the reaction namely, decreases the partial pressure propane order and activation energy of propene formation. XRD and XPS characterization of pure NiMoO_4 and mechanical mixtures before and after reaction revealed neither formation of new oxide phases between NiMoO_4 and α-Sb_2O_4 nor contamination of one phase by an element of the other phase. Confocal LRS indicated that the addition of α-Sb_2O_4 to NiMoO_4 modifies the coordination state of Mo in the NiMoO_4. These results could be explained as an action of oxygen spillover.