VANADIUM-PHOSPHORUS CATALYST MODIFIED WITH MANGANESE OR COBALT

Vanadium-phosphorus catalysts modified with Mn or Co elements essentia lly increase not only the specific rate of butane conversion and malei c anhydride formation but the selectivity of the process studied as we ll in comparison with the unmodified V-P-O catalyst. It seems likely t hat the effect of modifiers relates to the acido-basicity of the surfa ce and to lattice defects. The modifiers slightly decrease the apparen t activation energy (app. 4 kJ.mol(-1)) compared with the unmodified c atalyst.