Thermodynamics of glycerol hydrogenolysis to propanediols over supported copper clusters: Insights from first-principles study  

作　　者：GUAN Jing WANG XiCheng WANG XiaoYan MU XinDong 

机构地区：[1]Key Laboratory of Biofuels,Qingdao Institute of Bioenergy and Bioprocess Technology,Chinese Academy of Sciences

出　　处：《Science China Chemistry》2013年第6期763-772,共10页中国科学（化学英文版）

基　　金：the financial support from the Natural Science Foundation of Shandong Province (ZR2010BQ001 and O92003110C);the National Natural Science Foundation of China (20803038)

摘　　要：Copper catalysts supported on metal oxides display unique efficiency and selectivity in catalyzing glycerol hydrogenolysis to propanediols. Understanding the reaction at the molecular level is the key to rational design of better catalysts for propanediol synthesis, which is one of the major challenges for glycerol application in energy. In this work, extensive calculations based on periodic density functional theory were carried out to study thermodynamics of glycerol hydrogenolysis over binary model catalysts, including Cu/ZrO2 and Cu/MgO, with the focus to elucidate the competitive reaction pathways to produce the 1,2-propanediol (1,2-PDO) and 1,3-propanediol (1,3-PDO). Our results suggest that the reaction starts with glycerol dehydration on the metal oxide, followed by sequential hydrogenation over metal centers. Based on our explorations on the stabilities of adsorbed reactants, dehydrated intermediates and hydrogenated species along the reaction channels, the DFT calculations show that the 1,2-PDO formation will dominate in comparison to the 1,3-PDO from thermodynamic viewpoint. This is consistent with our experiments where the Cu catalysts seem to give the 1,2-PDO as a main product. The calculations and experiments also indicate that the Cu/MgO exhibits superior activities than Cu/ZrO2 for the hydrogenolysis of glycerol molecules.Copper catalysts supported on metal oxides display unique efficiency and selectivity in catalyzing glycerol hydrogenolysis to propanediols. Understanding the reaction at the molecular level is the key to rational design of better catalysts for propanediol synthesis, which is one of the major challenges for glycerol application in energy. In this work, extensive calculations based on periodic density functional theory were carried out to study thermodynamics of glycerol hydrogenolysis over binary model catalysts, including Cu/ZrO2 and Cu/MgO, with the focus to elucidate the competitive reaction pathways to produce the 1,2-propanediol （1,2-PDO） and 1,3-propanediol （1,3-PDO）. Our results suggest that the reaction starts with glycerol dehydra- tion on the metal oxide, followed by sequential hydrogenation over metal centers. Based on our explorations on the stabilities of adsorbed reactants, dehydrated intermediates and hydrogenated species along the reaction channels, the DFT calculations show that the 1,2-PDO formation will dominate in comparison to the 1,3-PDO from thermodynamic viewpoint. This is con- sistent with our experiments where the Cu catalysts seem to give the 1,2-PDO as a main product. The calculations and experi- ments also indicate that the Cu/MgO exhibits superior activities than Cu/ZrO2 for the hydrogenolysis of glycerol molecules.

关 键 词：density functional calculations glycerol hydrogenolysis propanediols copper-based catalysts MECHANISM 

分 类 号：O643.32[理学—物理化学]