Study On Catalytic Hydrogenolyzing System Of Biomass Glycerol

Biomass glycerol is an important raw material chemical used wide in various sectors of national economy and also is an ideal renewable resource that has been identified by the DOE as one of the top-12 building block chemicals in this century. Recently, more attention has been drawn on finding of new applications of glycerol, owing to the large surplus of this agent formed as a by-product during the production of biodiesel. Biomass glycerol is a promising feedstock for producing a wide range of value-added chemicals such as ethylene glycol, propanediol, acetol, dihydroxyacetone, diethylene glycol ether etc.Among them, hydrogenolysis of glycerol to 1,2-propanediol (denoted as 1,2-PDO) is believed a sustainable process with renewable potential application.In this paper, we investigate influencing factor of catalytic hydrogenolyzing glycerol to propanediol over Cu/Crcatalyst and the effects of cataltysts prepared methods and solvent on the hydrogenolysis reaction system of glycerol.1.Study on hydrogenolyzing glycerol to propanediol over Cu/Cr catalyst. A kind of Cu/Cr catalyst with high-surface area and high activity was prepared by co-precipitation method and tested for glycerol hydrogenolysis, the results in our work showed that when Cu and Cr atomic ratio is 1:1 and glycerol concentration is 50%, the hydrogenolysis conversion of glycerol to 1,2-propanediol is up to 100%, and selectivity is 97.5% in methanol solvent at 230℃,7MPa H2 pressure,600r/min speed and 5% catalyst weight. The product purity is up to 98.4% after distillation.2. The mechanism of glycerol hydrogenolysis to propanediols has been studied by two steps method to explore the reaction possible undergoing process. The reaction intermediate is separated by vacuum distillation, and then reacts with H2 in autoclave at high pressure. The investigation of our work exhibits that the mechanism for glycerol catalytic hydrogenolysis to propanediol may undergo dehydration-hydrogenation process.3. Influence of the preparation methods of Cu/Cr catalyst on glycerol hydrogenolysis to propanediol. Five kinds of Cu/Cr catalysts were prepared by various methods and used in glycerol hydrogenolysis reaction. The results of our experiment showed that the Cu/Cr catalysts prepared by copper ammonia complexing method exhibited better hydrogenolysis activities and hydrogenation performance for this catalyst not only could improve surface area, reduced the crystallinity degree of copper atoms and catalyst TPR reduction temperature, but also could promote the fusion and modulation of copper-chromium oxide crystalline phase. 4. Effects of solvents on catalytic hydrogenolyzing glycerol to propanediol has been studied. The influencing factors of the solvents effect were studied in terms of the solvent types, solvent polarity and catalyst deactivation in the solvents. The experiment results indicated that the raction activities are best in organic methanol solvent for its low viscosity, high dielectric constants, large ET and strong polarity, which destroy the intermolecular interaction between glycerol molecules, increase glycerol molecular dissolution and mass transfer of hydrogen in solvent and has little impact on the structure of the catalyst.