INVESTIGATION OF THE NATURE OF THE OXIDANT (SELECTIVE AND UNSELECTIVE) IN ON A VANADYL PYROPHOSPHATE CATALYST/

The anaerobic oxidation of CO by a (VO)(2)P2O7 catalyst has been used to investigate the nature of the oxidant (selective and unselective) i n/on that material. Three peaks were observed in the rate of productio n of CO2 - at 993, 1073 and 1093 K. The temperature of the maximum in the rate of production of the First CO2 peak and the amount of oxygen associated with it are the same as that observed in the selective anae robic oxidation of n-butane to butene and butadiene, but-1-ene to buta diene and furan and but-1,3-diene to dihydrofuran, furan and maleic an hydride. The interaction of CO with the (VO)(2)P2O7 catalyst forming C O2 at 993 K is therefore concluded to be with the selective oxygen. Th e total amount of oxygen removed by the CO from the (VO)(2)P2O7 lattic e (> 5 monolayers) is about six times greater than that of the selecti ve oxygen. The higher activation energies for the removal of the unsel ective oxygen accounts for the high selectivities (similar to 80%) enc ountered commercially for the anaerobic oxidation of n-butane to malei c anhydride. Re-oxidation of the CO reduced (VO)(2)P2O7 by N2O quantit atively replaces all of the lattice oxygen removed by the formation of CO2, but does not restore the original morphology.