Study On Hydrodeoxygenation Of Lignin To Hydrocarbons By Al Modified Molecular Sieve

With the rapid economic development,a sharp consumption of traditional petrochemical energy and environmental pollution are becoming increasingly serious,which prompt people to actively explore alternative new energy.Biomass is currently the only source of sustainable organic carbon.Among them,lignin is the only substance in nature with aromatic rings structure,contains a high energy density,and has great potential in the production of chemicals and fuels.However,the structure of lignin is stubborn and complex,and it is difficult to directly utilize it.Therefore,it is necessary to find a highly effective catalyst for hydrodeoxygenation of lignin.In this paper,an aluminum-modified molecular sieve carrier was prepared firstly,and then noble metals and transition metals were loaded on the modified molecular sieve carrier,finally,using these catalysts in the hydrogenolysis and hydrodeoxygenation of lignin.The products of cycloalkanes and aromatics from hydrogenolysis and hydrodeoxygenation of lignin can be used as biofuels,which provides the possibility for high value utilization of biomass resources.The main contents of this paper are as follows:（1）Al modified Al-HZSM-5 molecular sieve and HZSM-5 molecular sieve were used as carrier to prepare Ru/Al-HZSM-5 and Ru/HZSM-5 catalysts.The two catalysts were used in the hydrodeoxygenation of lignin,and the results showed that under the same conditions,the catalytic performance of Ru/Al-HZSM-5 catalyst was better than that of Ru/HZSM-5 catalyst.Through the analysis of BET and SEM,the specific surface area and pore volume of Ru/Al-HZSM-5 catalyst were larger than that of Ru/HZSM-5 catalyst.At the same time,the optimal process conditions of lignin hydrodeoxygenation were investigated.When m _lignin:m _catalyst=1:1,270℃,10h,800rpm,the conversion rate of lignin,liquid yield and solid residue were 86.43%,72.59wt%and 13.54wt%respectively,the yields of oxygen-containing aromatic compounds and hydrocarbon compounds in the light components were 2.63wt%and 18.32wt%,respectively,The main components of gas products were methane and carbon dioxide,and yields were 7.25wt%and 7.81wt%,respectively.Through the catalyst recycling experiment,it was found that the Ru/Al-HZSM-5 catalyst had a certain recycling effect,which would effectively reduce the cost of the catalyst.（2）In order to reduce the cost of catalyst preparation,transition metals were used to replace some precious metals.The effects of Ru-Cu,Ru-Ni,Ru-Co and Ru-Fe bimetallic Catalysts and the transition metal loading ratio were investigated of the activity of lignin hydrodeoxygenation.The experimental results showed that the Ru-Cu,Ru-Co,and Ru-Fe bimetallic catalysts catalyzed the low yield of hydrocarbon compounds in the hydrodeoxygenation of lignin,but Ru-Ni bimetallic Catalyst had the best hydrodeoxygenation effect,when the Ni loading was 10wt%,the lignin conversion was 78.25%,and the hydrocarbon yield was 13.21wt%.The experiment of hydrodeoxygenation of lignin oligomer was also carried out,and the influence of two solvents in the reaction were explored.The results showed that hydrodeoxygenation effect of the oligomer was better when water was the solvent,and the relative content of hydrocarbons and oxygenated aromatic compounds was 33.83%and 66.17%,respectively.