Catalytic Conversion Of Glucose On NiCu/MgO And Pt/CNTs Catalysts

Glucose is the basic structural unit of biomass. The catalytic conversion of glucose to produce high value-added chemicals is of great practical and scientific interest. The hydrogenolysis and oxidation of glucose are both potential conversion pathways. In this thesis, the catalytic activity of prepared solid-base MgO supported nickel-copper bimetallic catalysts have been tested by hydrogenolysis of glucose to form low-carbon polyol such as ethylene glycol and 1,2-propanediol. In addition, we preliminarily explored dehydrogenation of glucose to gluconate and hydrogen on Pt/CNTs catalyst.A series of bimetallic NiCu/MgO catalysts with different Ni/Cu ratios were prepared by co-precipitation route. The structural properties of NiCu/MgO catalysts were determined by N2-physisorption, X-ray diffraction, X-ray photoelectron spectroscopy and temperature-programmed reduction. The results indicated that the synergetic effect of copper and nickel existed which lowered the reduction temperature of NiCu/MgO catalysts and the formation of NiMgO2 inhibited reduction of Ni species. With increasing calcination temperature, the surface metal contents and Ni0/(Cu0+Cu+) ratios of catalysts and basicity of MgO significantly reduced by aggregation of copper oxide particles and migration of surface nickel oxide into NiMgO2 solid solution. The hydrogenolysis of glucose was employed for evaluating the catalytic performance of the bimetallic NiCu/MgO catalysts. The effects of various parameters such as Ni/Cu ratios, calcination temperature, H2 pressure, reaction temperature and time were studied systematically. It was found that the bimetallic catalysts exhibited higher activity for the hydrogenolysis of glucose to form C2-C4 products and 1,2-PD compared with the monometallic catalyst, due to the synergistic effect between Cu and Ni. When Ni/Cu= 1/4, the yields of C2-C4 and 1,2-PD products have increased to the maximum value,23.4% and 46.9%, respectively. The optimal reaction conditions of hydrogenolysis were obtained under a hydrogen pressure of 6 MPa at 413 K for 2 h and at 493 K for 5 h. The characterization results of NiCu/MgO catalysts after reaction indicated that the leaching of Mg was observed in the hydrogenolysis, due to the reaction of MgO carrier with water resulting in decompostion of MgO. A reuseability test of 1Ni3Cu/MgO showed that hydrogenolysis of glucose to C2-C4 and 1,2-PD is strongly dependent on the synergy of the MgO support and active components.The 2 wt% Pt/CNTs catalysts were prepared by impregnation method, ethylene glycol reduction method and urea precipitation method, which were used for dehydrogenation of glucose for evaluating the catalytic performance. The effects of various parameters such as preparation method, configuration and concentration of glucose and solvent were studied systematically. It turned out that 2 wt% Pt/CNTs catalyst prepared by urea precipitation method shows high activity of dehydrogenation. dehydrogenation activity of Pt/CNTs catalyst was inhibited by L-glucose, and dehydrogenation of D-glucose have a certain solvent effect. This provides an experimental basis for the industrial application of dehydrogenation of glucose.