| abstract |
【Task】 A shell-type impregnated catalyst of Pd—Au has a Pd amount of about 1.8 to about 7.2 g / L per liter of catalyst, and a weight ratio of Au to Pd is 0.3: 2.0. Thus, the support is made on a silica support and impregnated with an aqueous solution of palladium and gold salts or acids. Next, the impregnated carrier is reacted with an alkali metal silicate or hydroxide solution to precipitate a water-insoluble compound of Pd and Au on the carrier. Next, it is dried. Next, the compound of Pd and Au deposited on the surface is reduced by reacting with ethylene or hydrogen. In the case of ethylene, it is carried out at a temperature of 150 ° C. to 310 ° C., and in the case of hydrogen, it is carried out at a temperature of 150 ° C. to 299 ° C. The support is impregnated with potassium acetate until ˜7% weight percent. When producing vinyl acetate (VA), the space-time yield (STY) and specific activity (SA) when using such a catalyst is that of another catalyst composition produced from an impregnated catalyst reduced at 150 ° C. Compared to the case, the result is about 20 to 30% larger. When carried out under reaction conditions where STY is 600 or more when the temperature is 140 ° C. to 160 ° C. and the space velocity per hour at 120 psig is 4500 / hr, the selectivity of VA is 90% or more. It is shown that. |