| abstract |
HIGHLY ACITIVE CATALYSTS FOR THE PREPARATION OF CATALYSTS SUITABLE FOR VINYL ESTER, E.G., VINYL ACETATE, PRODUCTION ARE PREPARED BY TREATING A CATALYST SUPPORT, SIMULTANIOUSLY OR IN EITHER SEQUENCE, WITH OR WITHOUT INTERMEDIATE DRYING, WITH: (A) A SOLUTON OF NOBLE METALS CONTAINING AT LEAST SALTS OF PALLADIUM AND GOLD, AND (B) A SOLUTION CONTAINING COMPOUNDS, E.G., GASES SUCH AS SODIUM HYDROXIDE, WHICH ARE ABLE TO REACT WITH THE NOBLE METAL SALTS OF THE SOLUTION (A) TO FORM WATER INSOLUBLE NOBLE METAL COMPOUNDS; IMPREGNATING THE CATALYST SUPPORT WITH SUCH QUANTITIES OF SOLUTIONS (A) AND (B) CORRESPONDING TO FROM 10 TO 110% OF THE ABSORPTIVE CAPACITY OF THE CATALYST SUPPORT FOR THESE SOLUTIONS; SUBJECTING THE IMPREGNATED CATALYST SUPPORT TO A TIME TEMPERATURE TREATMENT SUCH THAT AT LEAST 95% OF THE IMPREGNATED PALLADIUM AND GOLD ARE TRANSFORMED INTO WATER INSOLUBLE NOBLE METAL COMPOUNDS; REDUCING THE METAL COMPOUNDS TO THE NOBLE METAL WITH A REDUCING AGENT, E.G., ETHYLENE OR HYDRAZINE; REMOVING THE WATER-SOLUBLE COMPOUNDS WHICH ARE CONTAINED IN THE CATALYST BY WASHING BEFORE OR AFTER THE REDUCTION STEP; AND OPTIONALLY TREATING THE RESULTING CATALYST WITH AN ALKALI METAL CARBOXYLATE, E.G., ACETATE, BEFORE OR AFTER THE TREATMENT WITH THE REDUCING AGENT. |