Preparation Of Nanoporous Ruthenium Catalyst And Catalyzed Hydrogenation Performance Of Guaiacol

Lignin is a renewable resource that can be converted to chemicals for other uses under specific conditions.Its conversion is meaningful for both replacing fossil resources and achieving environmentally friendly chemistry.The nanoporous Ru was studied for the hydrodeoxygenation of lignin unit model compound guaiacol,and then the model reaction was employed to evaluate the optimization of the catalyst preparation process.The guaiacol hydrodeoxygenation was carried out under different reaction conditions on the nanoporous Ru prepared by mechanical alloying(MA),and high temperature and low pressure(180 °C,1 MPa)conditions in the aqueous solution were favorable for the conversion of guaiacol.The mechanical alloying method was compared with melting methods.The alloy prepared by the MA was amorphous,the main metal crystal facet was Ru(100)and Ru(101)while the main crystal facet of the melting method were Ru(002).In order to understand the effect of the crystal facets,the adsorption energy of Ru crystals to guaiacol and the energy of two reaction paths on different crystal facets were calculated.The energy on Ru(100)was found to be lower for the hydrogenation of guaiacol than Ru(002).The activity of the catalyst was also affected by the interaction between the components.The stronger the interaction between Ru and Al,the higher the apparent activity of the catalyst.The Nb doped nanoporous Ru was employed by mechanical alloying,and the hydrodeoxygenation performance of guaiacol was improved through this modification.When the addition of Nb was 8.3 wt.%,the amount of stearic acid was 3 wt.%,and the speed of the ball mill was 500 rpm,the performance of the catalyst was better than the others.The yield of cyclohexanol could reach 78.2% at 180°C and hydrogen pressure of 1 MPa in 40 min.The pore size of the modified catalyst did not change much(10 nm),and the addition of Nb promoted the amorphization process,which increased the degree of fusion between the components.The acid sites of the catalyst were also changed after doping,with the weak acid center content increased and the strong acid center reduced.Nb was a solid lewis acid,so that the Al and Ru had lost electrons,which might also facilitate the interaction between the catalyst and substrate molecules.