| The depolymerization of lignin is currently a hot research topic in the field of the utilization of biomass resources.Catalytic hydrodeoxygenation is one of the effective methods to convert lignin into its monomer compounds.In this paper,the hydrodeoxygenation performance of Ni@C catalyst was examined,where the catalyst was prepared from the pyrolysis of nickel-based complex crystals and propylguaiacol,a typical lignin compound was chosen as the substrate.The results showed that the performance of the Ni@C catalyst is comparable to the precious metal Ru/C catalyst and much better than the Ni/C catalyst prepared by the impregnation method.When the reaction temperature is 240℃,the initial hydrogen pressure is 0.8 MPa,and the reaction time is 4 h,the propylguaiacol is almost completely converted on the Ni@C catalyst,and the yield of the main product,propylcyclohexanol,reaches 77.9%,which is better than that from noble metal Ru/C catalyst.The effects of reaction temperature,hydrogen pressure,reaction time and catalyst load on the reaction were further investigated,and it was found that the reaction temperature has a greater impact on the reaction performance than the change in hydrogen pressure.In addition,the performance of recycled catalyst was investigated.Based on the aforementioned studies,the reaction mechanism path of the system was preliminarily discussed.XRD,FT-IR,SEM,XPS,BET,NH3-TPD,H2-TPR,TGA-DTG,Raman spectroscopy and other analytical methods were used to characterize the changes in the preparation and reaction of Ni@C catalyst.XRD and XPS analysis showed that the catalytically active site is the nickel metal element Ni0.NH3-TPD analysis showed that the demethoxylation effect is due to the medium strong acid and strong acid sites on the catalyst.FT-IR and Raman spectroscopic analysis showed that the interaction between the catalytic active site Ni0 and the carbon support can stabilize the catalytic active site Ni0. |
