Claims
- 1. A method for preparing a catalyst for hydrogenolysis reactions of higher polyhydric alcohols, said method comprising the steps of:
- (a) preparing an aqueous solution comprising a compound of ruthenium and a second metal compound selected from the group consisting of palladium, platinum and rhodium compounds;
- (b) contacting the aqueous solution with an aqueous suspension of an activated carbon, and regulating the pH by adding an alkaline agent until a value of between 4.5 and 8 is obtained;
- (c) heating to a temperature of 60.degree. to 100.degree. C. for a time sufficient to cause the formation of a solid comprising compounds of the metals deposited on the activated carbon;
- (d) separating the solid;
- (e) suspending the solid obtained from the separation in an alkaline solution and hydrogenating the suspension thus obtained with gaseous hydrogen at a temperature of between 60.degree. and 100.degree. C. for a time sufficient to give rise to an intermediate catalyst comprising the metals in their metallic state deposited on the activated carbon;
- (f) adding to the suspension an aqueous solution comprising copper at a temperature lower than 50.degree. C. and maintaining the suspension at this temperature, under agitation, for a time sufficient to give rise to depositing of the copper on the intermediate catalyst, thereby forming the catalyst; and
- (g) recovering the catalyst, the concentration of the metals in the aqueous solution of step (a) and the copper solution of step (f) being such that the catalyst comprises:
- (i) 0.5 to 5 weight % ruthenium;
- (ii) 1 to 10 weight % of a metal selected from the group consisting of palladium, platinum and rhodium; and
- (iii) 0.5 to 2.5 weight % copper, the weight % of copper being lower than the weight % of the metal in (ii).
- 2. The method of claim 1, in which the activated carbon is in granulated form and has the following characteristics:
- (a) a specific surface area of 600 to 1000 m.sup.2 /g;
- (b) a total pore volume of 0.5 to 1.2 cm.sup.3 /g;
- (c) an apparent specific weight (bulk density) of 0.45 to 0.55 g/cm.sup.3 ;
- (d) an actual specific weight of 1.9 to 2.3 g/cm.sup.3 ;
- (e) a total volume of micropores having a radius smaller than 75 .ANG. of 0.4 to 0.55 cm.sup.3 /g; and
- (f) an ash content of 3 to 5 weight %.
- 3. The method of claim 2 in which the aqueous solution in step (a) is prepared by dissolving in water ruthenium trichloride and a palladium compound selected from the group consisting of H.sub.2 PdCl.sub.4 and Na.sub.2 PdCl.sub.4.
- 4. The method of claim 2, in which the copper solution of step (f) is prepared by dissolving copper formate in water.
Priority Claims (1)
Number |
Date |
Country |
Kind |
TO92A0080 |
Jan 1992 |
ITX |
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Parent Case Info
This is a divisional of U.S. application Ser. No. 08/011,189, filed Jan. 29, 1993, U.S. Pat. No. 5,326,912.
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Divisions (1)
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Number |
Date |
Country |
Parent |
11189 |
Jan 1993 |
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