Patent ID: 7704917

Claim:
A process for producing a catalyst for cyanhydrin hydration, the catalyst comprising a manganese oxide as a main component, potassium, and one or more elements selected from the group consisting of bismuth, vanadium and tin, which comprises: mixing the manganese oxide or a manganese-containing precursor thereof and compounds containing potassium and one or more of said elements together in an aqueous system; subjecting the resulting precipitate in a form of slurry to solid-liquid separation; and drying the resulting hydrous cake in at least two separate stages comprising a predrying and a main drying, wherein the predrying is carried out at a drying temperature of 20 to 50° C. and at an average drying rate of 2 to 10 wt%/hr (based on dry weight) until water content of the hydrous cake reaches 100 wt% (based on dry weight) at the maximum and wherein the main drying is carried out at a drying temperature of 100 to 200° C. until water content of the hydrous cake reaches 15 wt % (based on dry weight) at the maximum, whereby said catalyst is obtained.