Catalyst for the production of polyols by hydrogenolysis of carbohydrates

Abstract

A catalyst for the hydrogenolysis of carbohydrates is disclosed. The catalyst comprises nickel metal on an alumina-silica support. Optionally, the catalyst may be promoted with noble metals selected from the group consisting of copper, ruthenium, rhodium, palladium, platinum, gold, silver, and combinations thereof.

Description

BACKGROUND [0001] The present development is a catalyst useful for the production of polyols. Specifically, the invention is directed to the use of a nickel on alumina-silica catalyst for the hydrogenolysis of carbohydrates. Optionally, the catalyst may be promoted with noble metals. [0002] Polyols are commonly derived from sugars or carbohydrates. An aqueous solution of sugar is treated with hydrogen in the presence of a nickel catalyst to produce a sugar alcohol. The sugar alcohol, when further treated with hydrogen in the presence of the nickel catalyst, can be converted to polyols and glycols. [0003] Because the media for these hydrogenation reactions is water, it can be challenging to identify an effective, relatively long-lived catalyst for these processes. One approach identified in the prior art was to use colloidal metal. This avoided the problem that many common catalyst supports are not stable in water. However, it was difficult and expensive to remove the colloidal metal...

AI Technical Summary

Problems solved by technology

Because the media for these hydrogenation reactions is water, it can be challenging to identify an effective, relatively long-lived catalyst for these processes.

However, it was difficult and expensive to remove the colloidal metal from the resulting polyols and glycols.

Silica-alumina carriers are known in the art, but the '517 patent found these to be problematic: “nickel catalysts on a carrier (SiO2 / Al2O3)[have] extremely high active surfaces of 140-180 m2 / g so that the catalysts are so active that they must be stabilized by additional chemical treatment methods .

. . However, the deactivating stabilization of the catalyst then requires such high reaction temperatures during the hydrogenation of sugars (130-180° C.) that uncontrollable side reactions can occur . . .” In U.S. Pat. No. 4,382,150 (issued to Arena on May 3, 1983), the catalyst proposed is a zerovalent Group VIII metal dispersed on titanium dioxide: “whereas substantial amounts of silica and alumina, which are to (sic) commonly employed support materials, dissolve in the aqueous medium during hydrogenation of carbohydrates, virtually no leaching of titanium dioxide occurs under comparable hydrogenation conditions.

However, it is generally known in the art that Raney catalysts work well in static operations, but are not well-adapted to function effectively in continuous processes.