Hydrogenation catalyst, its method of preparation and use
A method of producing a hydrogenation catalyst, for example, a phthalate hydrogenation catalyst, comprising contacting a silica support having a medium pore size of at least about 10 nm with an acid to produce a treated silica support, and depositing a noble metal, preferably ruthenium, on the treated silica support to produce a noble metal-containing silica support, and optionally contacting the noble metal-containing silica support with a chelating agent to form the hydrogenation catalyst; a hydrogenation catalyst prepared by that method; and a method of hydrogenating unsaturated hydrocarbons, such as, phthalates, in which an unsaturated hydrocarbon is contacted with hydrogen gas in the presence of the hydrogenation catalyst of the invention.
1. A method for the preparation of a silica-supported noble metal hydrogenation catalyst comprising the steps of:
(a0) steam treating a silica material to obtain a steam-treated silica support having a median pore size of at least about 10 nm and no more than about 300 nm and a silica content of at least 60 wt %;
(a) contacting the steam-treated silica support with an acid to make an acid-treated silica support, thereafter calcining the acid-treated silica support at a temperature in the range of from about 250° C. to about 1000° C. to obtain a calcined silica support; and
(b) contacting the calcined silica support obtained in step (a) with a solution comprising a noble metal salt and a chelating agent to produce a noble metal-containing silica support, wherein the chelating agent has at least one carboxylic acid functional group or hydroxyl functional group and from 2 to 20 carbon atoms.
2. The method of claim 1 , wherein the noble metal is selected from the group consisting of ruthenium, rhodium, palladium, platinum and mixtures thereof.
3. The method of claim 1 , wherein the noble metal is ruthenium.
4. The method of claim 1 , further comprising the step of calcining the noble metal-containing silica support obtained in step (b).
5. The method of claim 1 , wherein the noble metal-containing silica support has a hydrogen to noble metal chemisorption ratio of at least about 0.50.
6. The method of claim 1 , wherein the silica support used in step (a) has a median pore size of at least about 20 nm.
7. The method of claim 1 , wherein the hydroxyl group concentration of the surface of the acid-treated silica support obtained in step (a) is at least 1 Si—OH group per nm 2 greater than that of the silica support used in step (a).
8. The method of claim 1 , wherein the acid used in step (a) is in the form of an aqueous solution having a pH of from about 0.0 to about +3.0.
9. The method of claim 1 , wherein the acid used in step (a) is nitric acid.
10. The method of claim 1 , wherein the steam-treated silica support used in step (a) has a crush strength of at least 800 g/mm.
11. The method of claim 1 , further comprising the step of activating the catalyst by contacting the noble metal-containing silica support obtained in step (b) with hydrogen gas.
12. The method of claim 1 , wherein the steam-treated silica support has a silica content of at least 80 wt %.
13. The method of claim 1 , wherein in step (a0), the silica material is steam treated at a temperature of at least 400° C.
14. The method of claim 1 , wherein in step (a0), the silica material is steam treated at a temperature in a range from about 500° C. to about 800° C.