Study On Catalytic Hydrogenolysis Of Sorbitol To C₂～C₃ Polyhydric Alcohols Over Ru/C Catalyst

C₂～C₃ polyhydric alcohols including ethylene glycol, propylene glycol and glycerol are widely used in the chemical fibre, automobile, food and medical industries. C₂～C₃ polyhydric alcohols were produced conventionally by the raw materials from petroleum resource. Therefore, with the the exhaustion of oil resource, the process of sorbitol hydrogenolysis to C₂～C₃ polyhydric alcohols shows broad propects due to its economic advantages,and it is based on biomass renewable resource, thus can meet the requirements of continuable development.In this paper, the Ru/C catalysts were prepared by the incipient wet impregnation method, using activated carbon as the support and RuCl₃ as the precursors. By means of TPR and activity evaluation, the proper preparation conditions were determined as follows: reduction temperature 300℃, reduction time 2h, and the loading of Ru active components 5wt%.The catalyst was used for the investigation on technological condition, the effects of catalyst dosage, pressure, temperature and addition of alkali on hydrogenolysis of sorbitol to C₂～C₃ polyhydric alcohols were studied. It was found that the suitable 5wt% Ru/C catalyst dosage was 0.25g, when 10g sorbitol were added. At the same temperature of 200℃, the yield of C₂～C₃ polyhydric alcohols also increased as with the increase of pressure. However, when the pressure increased to above 9MPa, the yield would start to decrease. With the temperature increasing, the hydrogenolysis rate of sorbitol also increased rapidly. The yield of products was enhanced to the highest of 73.41% at 270℃. At lower temperature, the addition of Ca(OH)2 was favorable to form C₂～C₃ polyhydric alcohols. When the temperature was above 240℃, the severe hydrogenolysis of sorbitol could decrease the yield of desired products.Using the GC-MS and HPLC analysis techniques, some TMS derivates of hydrogenolysis products were distinguished in order to explore, the mechanism of formation of C₂～C₃ polyhydric alcohols. The possible reaction routes and the formation conditions of by-products were also discussed.