Claims
- 1. A method for continuous production in a fixed bed reactor of lower polyhydric alcohols and their mixtures, comprising hydrogenolysis of higher polyhydric alcohols under pressure in the presence of a catalyst comprising from 0.5 to 5% by weight of ruthenium supported on granulated activated carbon, said catalyst having:
- a specific surface area of from 600 to 1000 m.sup.2 /g;
- a total pore volume of from 0.5 to 1.2 cm.sup.3 /g;
- an apparent specific weight (bulk density) of from 0.45 to 0.55 g/cm.sup.3 ;
- an actual specific weight of from 1.9 to 2.3 g/cm.sup.3 ;
- a total volume of micropores having a radius smaller than 75 A of from 0.4 to 0.55 cm.sup.3 /g; and
- an ash content of from 2 to 5% by weight.
- 2. A method according to claim 1, wherein the catalyst has a specific surface area of from 800 to 1000 m.sup.2 /g and a total pore volume of from 0.6 to 0.7 cm.sup.3 /g.
- 3. A method according to claim 1, wherein the catalyst has a particle-size distribution of 20-30% by weight of granules of between 10 and 18 mesh (2.0-1.0 mm) and 80-70% by weight of granules of between 18 and 35 mesh (1.0-0.5 mm).
- 4. A method according to claim 1, wherein the concentration of the ruthenium on the activated carbon is between 1 and 3% by weight.
- 5. A method according to claim 1, wherein the reaction temperature is between 220.degree. and 270.degree. C.
- 6. A method according to claim 1, wherein the higher polyhydric alcohols or mixture of higher polyhydric alcohols are supplied in an aqueous solution with a concentration of from 20 to 40% by weight, with a spatial velocity of the fluid supplied of between 0.3 and 4 h.sup.-1.
- 7. A method according to claim 6, wherein the spatial velocity of the fluid supplied is between 0.67 and 2.50 h.sup.-1.
- 8. A method according to claim 1, wherein the reaction pressure is between 7.5 and 20 MPa.
- 9. A method according to claim 6, wherein the supply solution comprises an alkaline or alkaline earth metal hydroxide as a reaction promoter, and the molar ratio between the higher polyhydric alcohols and the hydroxide is between 2 and 30.
- 10. A method according to claim 1, wherein the reactor is supplied with sulphides in a concentration of less than 150 ppm relative to the sulphide ion.
- 11. A method according to claim 1, wherein the higher polyhydric alcohol or mixture of higher polyhydric alcohols is the product of a first stage of hydrogenating carbohydrates in a fixed bed reactor with a low basic pH, using a catalyst comprising ruthenium in an amount from 0.5 to 5% by weight supported on active granulated carbon and having:
- a specific surface area of from 600 to 1000 m.sup.2 /g;
- a total pore volume of from 0.5 to 1.2 cm.sup.3 /g;
- a total volume of micropores having a radius smaller than 75 A of from 0.4 to 0.55 cm.sup.3 /g; and
- an ash content of from 2 to 5% by weight.
- 12. A method according to claim 11, wherein the pH in the first hydrogenation stage is between 7.5 and 8 in the presence of an alkaline or alkaline earth hydroxide.
- 13. A method according to claim 1, for continuous production in a fixed bed reactor of lower polyhydric alcohols and their mixtures, comprising hydrogenolysis of higher polyhydric alcohols under pressure as follows:
- (a) providing a fixed-bed reactor comprising said catalyst according to claim 6, wherein said catalyst is a hydrogenation catalyst capable of catalyzing hydrogenolysis of higher polyhydric alcohols under pressure;
- (b) supplying said fixed-bed reactor with a flow of an aqueous solution of a higher polyhydric alcohol, and a reaction promoter selected from the group consisting of alkaline hydroxides and alkaline earth hydroxides; and
- (c) collecting the reaction products from the fixed-bed reactor.
- 14. A method according to claim 13, wherein said flow of an aqueous solution to the fixed-bed reactor further comprises a sulphide reaction moderator in an amount lower than 150 ppm of said solution.
- 15. A method according to claim 13, wherein said activated carbon support is of a vegetable origin.
Priority Claims (1)
Number |
Date |
Country |
Kind |
TO92A0079 |
Jan 1992 |
ITX |
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Parent Case Info
This is a divisional of U.S. application Ser. No. 08/010,564, filed Jan. 28, 1993, now U.S. Pat. No. 5,403,805.
US Referenced Citations (8)
Number |
Name |
Date |
Kind |
3978000 |
Schmitt, Jr. et al. |
Aug 1976 |
|
4052336 |
Van Mutfoort et al. |
Oct 1977 |
|
4111842 |
Van Mutfoort et al. |
Sep 1978 |
|
4430253 |
Dubeck et al. |
Feb 1984 |
|
4476331 |
Dubeck et al. |
Oct 1984 |
|
4496780 |
Arena |
Jan 1985 |
|
4560672 |
Attig et al. |
Dec 1985 |
|
5403805 |
Gubitosa et al. |
Apr 1995 |
|
Foreign Referenced Citations (4)
Number |
Date |
Country |
075952 |
Apr 1983 |
EPX |
191373 |
Aug 1986 |
EPX |
2034292 |
Jun 1980 |
GBX |
2103649 |
Feb 1983 |
GBX |
Divisions (1)
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Number |
Date |
Country |
Parent |
10564 |
Jan 1993 |
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