Preparation Of Cu-and Ni-based Nanomaterials And Their Application In Syngas Conversion

Nanomaterials with excellent physical and chemical properties have triggered great interest and have played a significant role in fields such as energy and catalysis.The catalytic activity of nanomaterials highly depends on their size,structure and morphology.Controlled synthesis of nanomaterials plays an important role in revealing the relationship between structure and catalytic performance.Poor catalytic performance and unclear mechanism of reaction form obstacles in syngas conversion to methyl formate(MF)and methane.To solve these problems,ordered mesoporous CuO-CaO-ZrO2 catalysts for synthesis of methyl formate(MF)and Ni nanocrystal for methanation were synthesized,respectively.The specific findings include:(1)In order to reveal how the ordered mesoporous structure and distribution of Cu species impact the activity and the stability,a series of multicomponent Cu-Ca-Zr oxide catalysts with ordered mesoporous were synthesized by evaporation-induced self-assembly(EISA)method and used for direct synthesis of MF from syngas.The results indicate that the catalyst prepared by one-pot EISA method,in which the CuO species are highly dispersed in frame of CaO-ZrO2,exhibits better activity and stability as compared with the other two catalysts prepared by impregnation or nanoparticle immobilization method with most of CuO located on the outer surface of the CaO-ZrO2 support,because of its high specific area,the synergistic effect of two activity sites and the stronger interaction between the support and CuO active constituent.(2)Icosahedral Ni nanocrystals with face centered cubic(fcc)crystal structure and hexagonal prisms with hexagonal close packed(hcp)phase were prepared by solvothermal method and by using Ni(acac)2 as precursor,N,N-dimethylformamide(DMF)as the reducing agents and solvents and polyethyleneimine(PEI)as surfactant.The possible growth process is proposed by controlling reaction time.We first use the hcp Ni in the reaction of CO methanation and investigate the effect of Ni crystalline phase on its catalytic performance.The results show that Ni particles with hcp phase possess enhanced catalytic activity and anti-sintering ability compared with fcc Ni,because of its "self-abruption" effect.