Modification of the Surface Pathways in Alkane Oxidation by Selective Doping of Broensted Acid Sites of Vanadyl Pyrophosphate

Article abstract of DOI:10.1021/j100380a050

The modification of Broensted POH groups of (VO)2P2O7 by selective doping with K in an anhydrous medium causes a considerable modification of the surface oxidation pathways in C4- and C5-alkane oxidative transformation, with (i) a considerable decrease in the selective formation of maleic anhydride from n-butane and of maleic anhydride and phthalic anhydrides from n-pentane, (ii) an increase in the relative formation phthalic anhydride with respect to maleic anhydride from n-pentane, and (iii) an increase in the formation of C-containing surface residues.It is suggested that these effects are due to an inhibition of the catalyzed transformation of furan-like intermediates to corresponding lactones and then to anhydrides in the presence of gaseous O2 and to a change in the relative rates of O-insertion and H-abstraction on these surface intermediates.The role of the dynamics of competitive surface transformations of adsorbed intermediates on the overall behavior of vanadyl pyrophosphate in C4- and C5-alkane selective oxidation is also discussed.