GB625171A - Manufacture of hexitols or mixtures of isomeric hexitols by the catalytic reduction of carbohydrates - Google Patents

Abstract

Commercial glucose or similar mixture of glucose with maltose and/or dextrins is catalytically reduced in the liquid phase to hexitols by continuous passage, with the catalyst in suspension therein and with hydrogen, at elevated temperature and pressure, through a reaction zone in which the temperature is raised continuously or in stages from the inlet to the outlet end. Products of starch hydrolysis such as commercial glucose have the glucose content reduced at the low initial temperature, while the polysaccharides are only substantially reduced in the hotter portion of the reaction zone. A single tube-shaped reactor may be used or a plurality of reactors at different temperatures and pressures. Recycling of the reaction mixture or of the hydrogen may be effected. An acid catalyst may be added to the reactants to hydrolyse the polysaccharides. Hydrogen may be supplied through fine filters or partitions provided. The catalyst may be added as a pre-formed suspension or paste in the initial mixture or product. In an example, a 50 per cent aqueous solution of commercial glucose in which is suspended a nickel-diatomaceous earth catalyst is hydrogenated by passage through a tube at 100 atm. and a temperature rising from 140 DEG to 200 DEG C. from inlet to outlet to give sorbitol.