Application Of Molybdenum-based Bimetallic Sulfide Catalyst In Hydrodeoxygenation Of Guaiacol

Lignin is the only renewable resource with aromatic rings in nature.Therefore,the effective use of lignin is an effective method to promote the sustainable development of energy and ease the current energy shortage in the world.Under the action of the catalyst,the lignin undergoes a hydrodeoxygenation（HDO）reaction,which interrupts its long-chain structure and obtains high-value-added fine chemical products.In this paper,a series of molybdenum-based sulfide catalysts were prepared,and the hydrodeoxygenation performance of different catalysts on lignin model compounds with different C-C bonds and C-O bonds were studied.In the dissertation,MoCoZnAl-S sulfide catalysts were first prepared by hydrothermal,equal volume impregnation method and programmed temperature reduction and reduction method.With guaiacol as the reaction substrate,the solvent,Mo loading and the metal element Co:Zn were investigated.The influence of the molar ratio of Al to the catalyst activity shows that the optimal solvent is n-hexane,the optimal loading is 15%,and the optimal Co:Zn:Al molar ratio is 4:2:1.The physical and chemical structures were characterized by XRD,N₂ isothermal physical desorption and desorption,and STEM.Then the reaction conditions were investigated,and the best reaction conditions were obtained:the temperature was 300C,the initial hydrogen pressure was 5 MPa,and the time was 3h.Under the optimal reaction conditions,guaiacol achieved 100%conversion,the main product was benzene,the yield was 70%,the yield of phenol was 11.5%,and the yield of cyclohexane was 8.6%.In addition,the recycling performance of the catalyst was investigated.Subsequently,the metal Mg and Cu elements were investigated to replace the metal Zn elements respectively.MoCoMgAl-S and MoCoCuAl-S sulfide catalysts were prepared by hydrothermal method,impregnation method and programmed temperature sulfidation reduction method.Hydrodeoxygenation performance.At a temperature of300℃,an initial hydrogen pressure of 5 MPa,and a time of 3h,when the catalyst was MoCoMgAl-S,guaiacol was completely converted,and when MoCoCuAl-S was used as the catalyst,Lignin only converted 88.2%,with a lower conversion rate.The corresponding main products are phenol and benzene,respectively,with yields of 60%and 53.7%,respectively.Finally,in order to study the ability of the molybdenum-based sulfide catalyst to activate different C-C and C-O bonds in the lignin structure,the initial pressure of hydrogen was 5 MPa,the temperature was 300℃,and the time was 3h.S is the catalyst.Monomer model compounds such as anisole,phenol,and p-cresol,and dimer model compounds such as diphenyl ether,dibenzyl ether,and benzyl phenyl ether are used as probe substrates for hydrodeoxygenation the study.MoCoZnAl-S catalyst completely converted p-cresol,dibenzyl ether,diphenyl ether,benzyl phenyl ether.The conversion rate of anisole was 90.5%,and the conversion rate of phenol was 99%.Ability to break C-O bonds and hydrodeoxygenation activity.