Pd/V2O5-SiO2 catalyst for oxidative dehydrogenation of isobutane with CO2 to isobutene

A series of supported Pd catalysts were prepared by incipient impregnation using a V2O5-SiO2 surface complex prepared by surface modification as the support. Their structure, valence states, chemisorption properties for isobutane, and catalytic activity for isobutane partial oxidation with CO2 were characterized by N-2 adsorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed desorption, chemisorption-infrared spectroscopy, and microreactor techniques. The results showed that the lattice oxygen of V=O was the active site on the Pd/V2O5-SiO2 catalyst, and the valence of vanadium in the V=O was positive 5. Isobutane was chemisorbed on the lattice oxygen of V=O through the H atoms in -CH3 and -CH of i-C4H10. Carbon dioxide was chemisorbed horizontally on the catalyst through the synergetic effect of Pd and V4+. The V5+ <-> V4+ couple played a key role in the redox mechanism of the catalytic reaction. In the presence of Pd/25% V2O5-SiO2 and under the conditions of 525 degrees C, 0.1 MPa, CO2/i-C4H10 volume ratio of 1, and mixed gas space velocity of 1200 h(-1), 22.8% conversion of isobutane and 89.1% selectivity for isobutene were achieved.