VANADIUM-PHOSPHORUS CATALYSTS MODIFIED WITH MAGNESIUM, CALCIUM AND BARIUM

Vanadium-phosphorus catalysts specially modified with promoters can en sure an efficient and selective oxidation of C-4 hydrocarbons, even al so that of butane to maleic anhydride. The catalysts with incorporated Mg, Ca or Ba ions provide a higher conversion of butane, yield of mal eic anhydride, and selectivity for the latter compound than the unmodi fied catalyst. The conversion of butane and yield of maleic anhydride decrease with increasing basicity of the incorporated modifiers in the order: Mg, Ca, Ba, however, the selectivity of formation of maleic an hydride increases in the opposite order, which is interpreted by the i dea that on the modified V-P catalysts the conversion of butane decrea ses faster than the yield of the anhydride with the natural basicity o f the above-mentioned modifiers.