| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a heteropolymerization catalyst of a specified composition used for the preparation of methacrylic acid by gas phase contact oxidization by mixing a catalyst raw material into water, dissolving or suspending, heating in the state of presence of ammonium in a mixed liquid, concentrating and drying a suspension, burning the suspension in an inactive gas. SOLUTION: The heat treatment is carried out at the temperature of 80-200 deg.C for 1-24 hours in the state of the presence of ammonium in a liquid mixed with an ammonium salt and the like, and a suspension is concentrated, dried and solidified, and a dry solidified material is burnt in an inactive gas up to 400-500 deg.C to prepare a catalyst for preparing methacrylic acid. The catalyst is a partially neutralized salt of a heteropoly-acid represented by the formula. In the formula, X represents at least one kind of element selected from the group consisting of rubidium, cesium and thallium. The letters of (a), (b), (c), (d), (e), (f) and (g) represent the atomic ratio of respective elements and when b=12 is set, (a), (b), (c), (d), (e) and (f) represent the values of less than 3 not including 0 respectively, while (g) represents the value by the valences and atomic ratios of other elements. |
