| 摘要 |
PURPOSE:To produce methacrylic acid in high yield and selectivity by catalytically oxidizing methacrolein with molecular oxygen by using a specific catalyst prepared by adding a specified element to a P-Mo-Sb-Cu system and heat- treating the resultant system. CONSTITUTION:Methacrolein is catalytically oxidized with molecular oxygen in the vapor phase by using a catalyst expressed by the formula [X is Co, Ni, Nb, Ag or W; Y is Cr, Mn, Fe, Zn, W, etc.; when (a) is 12, (b) is 0.5-3; (c) is 0.5-2; (d) is 0.5-2; (e) is 0-2; (f) is 0-2; (e+f) is not 0; (g) is determined by the oxidation state of the catalyst] to afford methacrylic acid. This catalyst used therein is obtained by adding a specific element to a catalyst containing P, Mo, Sb and Cu, passing the resultant catalyst through an ammonium salt type heteropoly acid, heat-treating and converting the heteropoly acid into a proton type heteropoly acid. The resultant catalyst assumes an ammonium salt type heteropoly acid structure without containing an ammonium salt and is valuable as an industrial catalyst. |
