INFLUENCE OF ZIRCONIUM-PHOSPHATE ON THE PROPERTIES OF (VO)(2)P2O7 CATALYSTS FOR THE SELECTIVE OXIDATION OF N-BUTANE TO MALEIC-ANHYDRIDE

The effect of zirconium phosphate on the catalytic, textural and struc tural properties of (VO)(2)P2O7 catalysts has been studied. Catalysts with different P/V and Zr/V ratios were prepared using different prepa ration methods and characterized by thermoanalytical and texture measu rements, X-ray diffraction (XRD), potentiometric titration, FTIR, X-ra y absorption [X-ray absorption near-edge structure (XANES) and extende d X-ray absorption fine structure (EXAFS)] and laser Raman spectroscop y. The n-butane conversion and the maxima of maleic anhydride (MA) yie ld shift to lower reaction temperatures on modification of (VO)(2)P2O7 with zirconium phosphate. There is no correlation between catalytic a nd textural properties of the modified catalysts. The zirconium phosph ate modification causes a partial amorphization of the (VO)(2)P2O7 cat alysts and leads to an enhancement of the VOPO4 microdomains (alpha(1) , beta-VOPO4 and amorphous VOPO4).