Study On The Synergistic Effect Of Encapsulated Metal And Acid On Hydrogenolysis Of Biomass

In this paper,the application of encapsulated metal and acid synergistic catalysts in the hydrogenation and hydrogenolysis of biomass was studied,which provided ideas for conversion of biomass and its derivatives to biofuels.The development of dual-function catalysts with high efficiency and stability is the key to promote hydrogenation and hydrogenolysis reaction.The synergistic effect between metal site and acid site determines the reaction rate and the selectivity of the target product in hydrogenation and hydrogenolysis reaction.Therefore,it is very important to design a kind of dual-function catalyst with rich metal-acid interface for hydrogenation and hydrogenolysis of biomass derivatives.In order to solve the above problems,a series of dual-function multihole catalysts with encapsulated metal-acid interface were designed by using two different catalyst supports,which are MOF and zeolite.The main research contents are as follows:（1）Metal-organic framework catalysts（Pd@Ui O-CH₂SO₃H,Pd@Ui O-Ph SO₃H）were prepared by impregnation method through strong coordination between noble metals and sulfhydryl groups,and were applied to hydrogenation and hydrogenolysis of biomass derivatives.Compared with traditional surface-supported metal catalysts（Pd/Ui O-CH₂SO₃H,Pd/Ui O-NH₂）,the MOFs encapsulated in Pd-acid interface showed higher activity and selectivity for the conversion of MF to DMF,HMF to DMF,and VA to MMP.Among them,Pd@Ui O-CH₂SO₃H has the best catalytic performance,DMF yield of MF reaction and HMF reaction is 89.0%and 86.0%respectively,and MMP yield of VA reaction is 99.4%,which is mainly due to its great hydrophilicity,high hydrogen activation ability and Pd-SO₃H interface synergistic catalytic activity.According to the catalytic performance of Pd/Ui O-NH₂ and ATR-IR test results,the acidic sites on the Pd-acid interface can accelerate the activation of hydroxyl groups in hydrogenolysis reactions.This work provides an effective design strategy for the preparation of MOF encapsulated metal-acid interface and demonstrates the powerful synergistic effect of hydrogenation and hydrogenolysis catalysis.（2）A mesoporous zeolite catalyst（Pd@meso-ZSM-5）for confined encapsulated Pd nanoparticles was prepared by reverse microemulsion method and dry-gel conversion method,which was applied in the multilevel cascade reaction of cyclic ketones（cyclopentanone,cyclohexanone）to cycloalkanes（cyclopentane,cyclohexane）.Compared with surface-supported catalysts（Pd/ZSM-5）and microporous zeolite encapsulated Pd catalysts（Pd@ZSM-5）,the yield of dicycloalkanes over Pd@meso-ZSM-5 catalyst can reach more than 78%.Controlled experimentation and detailed characterization showed that the mesopore provided sufficient space for the conversion and diffusion of macromolecular intermediates,and the dense and rich Pd-acid interface promoted the conversion of intermediates through powerful dual-functional catalysis.In this work,the design strategy of metal-encapsulated mesoporous zeolite was proposed,and the idea of highly synergistic effect between acid catalysis and hydrogenation catalysis is provided.