Preparation of catalysts

Claim 1

A PROCESS FOR THE PRODUCTION OF A COMPOSITE CATALYST COMPRISING AN AUQEOUS SOLUTION OF PHOSPHORIC ACID IMPREGNATED UPON A POROUS SILICEOUS CARRIER MATERIAL, SAID PROCESS COMPRISING: A. SATURATING A CARRIER MATERIAL CONSISTING OF A POROUS CERAMICALLY BONDED AGGREGATE OF DIATOM SKELETONS RESULTING FROM THE CALCINATION OF A MATERIAL COMPRISING ESSENTIALLY THE SKELETONS OF DIATOMS IN INTIMATE ADMIXTURE WITH A MINOR AMOUNT, RELATIVE TO THE WEIGHT THEREOF, OF CLAY WITH A SOLUTION OF PHOSPHORIC ACID CONTAINING AT LEAST 70% BY WEIGHT OF H2PO4, B. HEATING THE RESULTING PHOSPHORIC ACID-SATURATED CARRIER MATERIAL AT A TEMPERATURE OF FROM ABOUT 150*C. TO ABOUT 400*C. IN AN ATMOSPHERIC CONTAINING WATER VAPOR SUFFICIENT IN AMOUNT THAT THE PARTIAL PRESSURE OF WATER VAPOR IN SAID ATMOSPHERE IS AT LEAST 50 MILLIMETERS MERCURY, BUT LESS THAN THE PARTIAL PRESURE OF WATER VAPOR IN AN ATMOSPHERE IN EQUILIBRUIM WITH THE AQUEOUS SOLUTION OF PHOSPHORIC ACID MENTIONED IN STEP A AT THE TEMPERATURE AT WHICH SAID HEATING IS EFFECTED, C. DIGESTING THE RESULTING HEATED PHOSPHORIC ACID-SATURATED CARRIER MATERIAL IN AT LEAST THREE-QUARTERS OF ITS VOLUME OF WATER HAVING A PH OF 2.5 OR LESS, D. IMPREGNATING THE RESULTING DIGESTED CARRIER MATERIAL WITH AN AQUEOUS SOLUTION OF PHOSPHORIC ACID CONTAINING AT LEAST 50% BY WEIGHT OF H3PO4.