Synthesis And Application Of Hierarachical Porpous Materials

Microporous zeolites are not beneficial to the diffusion of reagents and reaction because of small channels. And the hydrothermal stability and acid of mesoporous zeolite are poor. In order to overcome the shortcomings of microporous or mesoporous materials with the single channel, more and more researchers devote to develop the hierarchical zeolites. The hierarchical zeolites are composed of two or more length scales of the porosities. Micro-mesoporous zeolites combining the advantages of microporous and mesoporous structure can improve the performance of the zeolite. Zeolite Y with high surface area, strong acidity, excellently hydrothermal stability has been widely used in the industry. Furfural is an important component in bio-oil which prepared from biomass pyrolysis. Cyclopentanone as a kind of important fine chemical intermediate can be generated by furfural aqueous-phase catalytic hydrogenation. In this thesis, the hierarchical Y zeolites were synthesized by a simple process. The Ni catalysts which prepared using hierarchical Y zeolites as support were investigated on aqueous-phase hydrogenation of furfural, and the optimal reaction conditions were obtained.Hierarchical Y zeolite F-NaY with good crystallinity was successfully synthesized using traditional surfactant F127 as template without any additives. The influences of crystallization temperature, crystallization time, silica alumina ratio, amount of template for the synthesis of hierarchical Y zeolite were investigated. The results showed that hierarchical F-NaY-0.034 zeolite had better crystallinity, larger surface area and pore volume, the most appropriate acid under the crystallization temperature of 100 ℃, crystallization time 25 h, SiO2/Al2O3 of 10.5, the quality of F127 take up of the total quality of the reaction mixture ratio (g/g) of 0.034.Hierarchical Y zeolite S-NaY with good crystallinity was synthesized using cheap biological chemical products sodium alginate as template. The influences of crystallization temperature, crystallization time, silica alumina ratio, amount of template for the synthesis of hierarchical Y zeolite were investigated. The result showed that hierarchical S-NaY-0.018 zeolite had better crystallinity, larger surface area and pore volume, the most appropriate acid under the crystallization temperature of 100 ℃, crystallization time 25 h, SiO2/Al2O3 of 10.5, the quality of sodium alginate take up of the total quality of the reaction mixture ratio (g/g) of 0.018.The catalysts Ni/F-HY and Ni/S-HY were prepared using the hierarchical Y zeolite as support. Effect of support prepared with different amount of the template were mainly investigated on the aqueous-phase hydrogenation of furfural. Also comparing the catalytic performance used traditional Y zeolite as support. The results showed that 20wt.%Ni/F-HY and 20wt.%Ni/S-HY catalysts used two kinds of hierarchical Y zeolite as support performed higher catalytic activity than traditional Y zeolite. Mainly due to the multilevel structure of the support accelerates the reaction and mass transfer rate. Also the hierarchical catalysts have more suitable acid and higher surface area.In F127 as the template to prepare catalysts system, the catalyst showed highest activity when F127 amount is 0.034. At a reaction condition of 150 ℃ reaction temperature,4 MPa initial H2 pressure,9 h reaction time,20wt.% Ni loading,1.5wt.% amount of catalyst, a 94.8% conversion of furfural with 81.2% selectivity to cyclopentanone was obtained.In sodium alginate as the template to prepare catalysts system, the catalyst showed highest activity when sodium alginate amount is 0.018. At a reaction condition of 150 ℃ reaction temperature,4 MPa initial H2 pressure,9 h reaction time,20wt.% Ni loading,1.5wt.% amount of catalyst, a 96.4% conversion of furfural with 89.7% selectivity to cyclopentanone was obtained.Comparing two kinds of synthetic system used different template, the catalyst which used sodium alginate as the template showed higher catalytic activity. The superiority of the catalyst used sodium alginate as the template includes as following:More mesoporous volume of the support, which induces a fast diffusion rate of the reactants and products and more opportunity to contact active site. The catalyst prepared in this system has more acid amount. In terms of the dispersion of Ni, Ni metal particle dispersion is better on the surface of the catalyst prepared in this system.