Hydrogenation Of Ethyl Levulinate Catalyzed By Ni-based Bimetallic Nanoparticles Supported On Beta Zeolite

Ethyl levulinate（EL）is a biomass derived platform molecule that can be converted to a variety of value-added organic oxygenates.Ethyl-4-ethoxy pentanoate（EEP）is an important etheric ester with broad potential applications such as renewable fuel additives,surfactants and green solvents.The traditional synthesis of EEP uses mineral acid which catalyzes the ring-opening of gamma-valerolactone in ethanol.The usage of mineral acid results in corrosion of equipment and environment pollution.This thesis is committed to developing environmentally friendly synthetic method and catalysts for the production of EEP starting from EL in presence of H₂.In the first part,Ni₅X₂/Beta bifunctional catalyst（X=Re,Mo,W,Zn,Cu,Co,Fe）was prepared by simple impregnation method using Beta zeolite as the support.The results of characterization showed that the reducibility and dispersion of Ni O was influenced by the addition of the second metal.In addition,the acid site of the zeolite was affected by the metal component.Under the same reaction conditions,the hydrogenation activity of catalysts follows the trend:Ni Re,Ni Fe>Ni Cu,Ni Co,Ni Mo,Ni Zn>Ni>Ni W,and the selectivity of EEP follows the trend:Ni Re,Ni Cu,Ni>Ni Fe,Ni Zn>Ni Co,Ni Mo>Ni W.In the second part,the effect of Re on the metal and support was investigated.The characterization results showed that the interaction between Re and Ni significantly improved the dispersibility and reducibility of Ni O in Ni Re/Beta bimetallic catalysts.The Re introduced mainly exists as Re O_x,which decreases the D-band electron density of Ni,enhances the ability to activate H₂ and C=O bond.In addition,Ni Re O_x/Beta catalyst showed a large number of Lewis acid sites and a certain amount of Br（?）nsted acid sites.The combination of homogeneously dispersed Ni-Re bimetal nanoparticles and unique acidity renders great performance in the hydrogenation of EL to EEP.Under optimized reaction condition,160°C,1 MPa H₂and reaction time of 2 h,almost full conversion of EL with 83%yield of EEP could be achieved in ethanol.