Abstract: 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 N2 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[KG-45x]=[KG-20x]O was the active site on the Pd/V2O5-SiO2 catalyst, and the valence of vanadium in the V[KG-45x]=[KG-20x]O was positive 5. Isobutane was chemisorbed on the lattice oxygen of V[KG-45x]=[KG-20x]O through the H atoms in -[KG-20x]CH3 and -[KG-20x]CH of i-C4H10. Carbon dioxide was chemisorbed horizontally on the catalyst through the synergetic effect of Pd and V4+. The V5+←[KG-*4]→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 ℃, 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.

Key words: palladium, vanadium pentoxide, silica, surface complex, carbon dioxide, isobutane, oxidative dehydrogenation, isobutene