Historically, skeletal nickel is the catalyst of choice in the production of sorbitol on industrial scale. A disadvantage of the use of skeletal nickel in the hydrogenation of glucose containing feedstocks to sorbitol, is the fact that a part of the nickel leaches. As a consequence, purification of the sorbitol is required, which renders this process economically less attractive. To meet the demand for non-leaching catalyst systems, ruthenium on carbon catalyst are presently becoming more important. In this paper, a comparison is made between different 5% Ru on carbon catalysts in the hydrogenation of a dextrose monohydrate and a very high maltose feedstock. The influence of the carbon support, the ruthenium metal location, and the applied ruthenium precursor are investigated. For comparison reasons, both skeletal Ni and Ru catalysts have been applied in the hydrogenation of dextrose to sorbitol. The effect of reaction temperature and pressure during the hydrogenation of a very high maltose containing feedstock is also investigated. It is shown that Ru catalysts are suitable alternatives for skeletal Ni catalysts in respect to re-usability, activity and selectivity. (C) 1999 Elsevier Science B.V. All rights reserved.
