Preparation Of Highly Dispersed Ruthenium-based Catalysts And Their Catalytic Performances For The Hydrodeoxygenation Of Lignin-derived Phenolic Compound

With the rapid consumption and non-renewability of fossil energy,researchers have focused their attention on the development and utilization of green energy.Biomass has attracted much attention as the most promising substitute for fossil resources.Lignin is an important part of biomass resources.Catalytic hydrodeoxygenation of depolymerizing products of lignin can produce important chemicals and fuels,and the development of high-efficiency catalysts is the key to the hydrodeoxygenation of lignin depolymerization products.At present,noble metal catalysts have been used in the research of hydrodeoxygenation of lignin depolymerization products,but the reaction conditions are relatively harsh.Therefore,it is of great significance to design and develop catalysts to achieve efficient catalytic hydrodeoxygenation of lignin depolymerization products under mild conditions.According to the characteristics of layered double hydroxides（LDHs）such as adjustable layer elements and exchangeable interlayer anions,a composite metal oxide carrier with abundant porous structure and acid sites can be obtained through the topological transformation of LDHs.In this thesis,the supported Ru catalyst was prepared by selecting ZnAlPW composite metal oxide as a carrier,which was obtained by using phosphotungstic heteropolyanion intercalated ZnAl-LDH,and Ru as a metal.active component,which has higher catalytic hydrogenation activity and lower price.At the same time,Ru-based catalysts were prepared with zinc tungstate with different morphologies as supports.The research results revealed the structure-activity relationship between the microstructure and morphology of the catalyst supports and the low-temperature hydrodeoxygenation conversion of guaiacol.The detailed work is as follows:1.In this paper,ZnAl hydrotalcite（ZnAlPW-LDH）intercalated with phosphotungstic heteropolyanion was prepared by ion exchange method,and then calcined at high temperature to obtain composite metal oxide（ZnAlPW-MMO）.The Ru nanoparticles were loaded on the ZnAlPW-MMO carrier by the NaBH4 reduction method,and the supported Ru catalyst（Ru/ZnAlPW）was prepared and applied to the hydrodeoxygenation reaction of guaiacol.The results of catalytic performance test showed that under the conditions of 250℃ reaction temperature,2 MPa H2 and 1 hours,the Ru/ZnAlPW catalyst was used in the hydrodeoxygenation of guaiacol to produce cyclohexanol with high selectivity,and the yield of the target cyclohexanol reached 88.18%.HRTEM,specific surface pore size distribution,XPS,H2-TPD,H2-TPR,NH3-TPD and in-situ FTIR characterization results show that the research results showed that the Ru/ZnAlPW catalyst surface has highly dispersed Ru nanoparticles and abundant porous structure and moderately strong acid sites.The Ru/ZnAlPW catalyst exhibited high-efficiency hydrodeoxygenation activity under mild conditions due to the presence of highly dispersed Ru nanoparticles,abundant acid sites and oxygen defects in the catalyst,which not only facilitated the adsorption and activation of hydrogen and guaiacol,but also provided more active sites.2.ZnWO₄ nanomaterials with different morphologies were obtained by hydrothermal method with different conditions and used as carriers to prepare highly dispersed supported Ru-based catalysts for the hydrodeoxygenation reaction of guaiacol,and the effects of the amount of Ru metal loading,reaction temperature,hydrogen pressure and reaction time on the hydrogenation activity of guaiacol were investigated.The results showed that under the conditions of250℃ reaction temperature,2 MPa H2 and 1 hours,the catalyst 2Ru/ZnWO₄-B exhibited the best catalytic performance,the conversion rate of guaiacol was 93.63%,and the yield of the target cyclohexanol reached was 83.37%,which was attributed to the abundant Lewis acid sites on its surface,in addition,high temperature and low pressure conditions were conducive to the removal of methoxy groups,and the increase in the content of active component Ru can effectively promote the conversion of guaiacol,but reduces the yield of deoxygenated products.