Modification of the surface pathways in alkane oxidation by selective doping of Broensted acid sites of vanadyl pyrophosphate

The modification of Broensted POH groups of (VO)2P2O7 by selective doping with K in an anhyd. medium causes a considerable modification of the surface oxidn. paths 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 and phthalic anhydrides from n-pentane, (ii) an increase in the relative formation of phthalic anhydride with respect to maleic anhydride from n-pentane, and (iii) an increase in the formation of C-contg. surface residues. 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. 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 oxidn. is also discussed. [on SciFinder(R)]