| 摘要 |
1,243,105. Silver metal catalyst. SOC ITALIANA RESINE S.p.A. 17 Nov., 1969 [23 Nov., 1968], No. 56241/69. Heading B1E. [Also in Division C2] A catalyst comprising silver supported on a solid inert particulate support in a quantity of 7 to 30%by wt of the support and at least one of Pt, Pd or An or an oxide thereof in a quantity of 0.01 to 1.0 % by wt based on the silver is prepared by (i) impregnating the carrier with an aqueous suspension of silver oxide and at least one metal or oxide of Pb, Pd and Au, (ii) drying the impregnated carrier, the temperature being raised to a level not exceeding 130‹C over a period of one hour, (iii) further impregnating with an aqueous solution of one or more of acetic acid, lactic acid, citric acid, malic acid, and isomalic acid and/or the silver salts of these acids at 60‹ to 100‹C, the ratio of the number of carboxyl groups (free and salified) to the number of silver atoms used being from 1:2 to 1:10, (iv) drying at atmospheric pressure or below at 60 to 130‹C and (v) heating to a max of 230‹C to 360‹C over a period of 15 to 48 hours. The amount of silver oxide used in step (i) is not less than 70% of that required to produced the desired silver content of the finished catalyst, any balance being made up in the form of silver salts in step (iii). Specified supports are alumina, silicon carbide and magnesium oxide, suitably in the form of spheres of diameter 4 to 9mm. The preferred support is alphaalumina which has been activated by treatment above 1000‹C., has a surface area of 0.01 to 1.0 sq. m/gm and has a porosity of 10 to 40% with a mean pore diameter of 30 to 150 microns. |
