초록 ▼

The present invention provides a process for preparation of low molecular weight polyols from high molecular weight polyols in a hydrogenolysis reaction under elevated temperature and hydrogen pressure. The process comprises providing in a reaction mixture the polyols, a base, and a metal catalyst p

The present invention provides a process for preparation of low molecular weight polyols from high molecular weight polyols in a hydrogenolysis reaction under elevated temperature and hydrogen pressure. The process comprises providing in a reaction mixture the polyols, a base, and a metal catalyst prepared by depositing a transition metal salt on an inert support, reducing the metal salt to the metal with hydrogen, and passivating the metal with oxygen, and wherein the catalyst is reduced with hydrogen prior to the reaction. In particular, the process provides for the preparation of glycerol, propylene glycol, and ethylene glycol from sugar alcohols such as sorbitol or xylitol. In a preferred process, the metal catalyst comprises ruthenium which is deposited on an alumina, titania, or carbon support, and the dispersion of the ruthenium on the support increases during the hydrogenolysis reaction.

대표청구항 ▼

[ We claim:] [1.]1. A process for preparation of low molecular weight polyols which comprises:(a) providing a transition metal catalyst prepared by depositing a transition metal salt in a solvent on an inert support, drying to remove the solvent, reducing the metal salt to the metal with hydrogen, a

[ We claim:] [1.]1. A process for preparation of low molecular weight polyols which comprises:(a) providing a transition metal catalyst prepared by depositing a transition metal salt in a solvent on an inert support, drying to remove the solvent, reducing the metal salt to the metal with hydrogen, and passivating the metal in an oxygen containing atmosphere so as to provide an oxide of the metal on the surface of the metal in a reaction vessel;(b) reacting the catalyst with hydrogen in the vessel;(c) providing in the vessel a reaction mixture of a high molecular weight polyol in water and a base promoter;(d) reacting the reaction mixture containing the base with the catalyst and hydrogen at an elevated temperature and hydrogen pressure wherein the temperature is between 180.degree. C. and 250.degree. C. and the hydrogen pressure is between about 3.4 to 14 MPa (500 to 2,000 PSIG) to produce low molecular weight polyols in the reaction mixture;(e) removing the reaction mixture with the lower molecular weight polyols from the vessel;(f) recovering the low molecular weight polyols from the reaction mixture along with unreacted hydrogen; and(g) separating the unreacted hydrogen from the reaction mixture and purifying to greater than 90% by volume hydrogen with the removal of methane; and(h) recycling the purified hydrogen to the reaction mixture.