Experimental Study On Catalytic Liquefaction Of Lignin By Magnetic Core-shell Catalyst

Because of excessive development and use of fossil fuels,fossil fuels are dwindling and the energy crisis and environmental problems become more and more serious.The development of the renesable and sustainable green energy with low carbon contents is seriously considered.Lignin is the second abundant polymer on earth.It is the only renewable biomass which is composed of a large number of aromatic hydrocarbon.Using lignin conversion technologies to produce fuel and high value-added chemical products becomes the effective way to solve the problem of energy crisis and environment.The liquefaction of lignin in supercritical methanol with catalyst was studied in this paper.Hydrotalcite of Fe3O4@SiO2@CuZnAl-O were prepared through parallel flow co-precipitating method.Fe3O4@SiO2@CuZnAl-O catalyst was obtained from hydrotalcite which was calcinated at 500 ? in N2 atmosphere for 2h.Physical and phase structure of the catalysts which contained different Cu/Zn mole ratios(1:5,1.2:4.8,1.5:4.5,2:4,3:3)were studied by X-ray diffraction(XRD),N2 absorption-adsorption(BET),Transmission electron microscope(TEM)and Scanning Electron microscope(SEM)analysis.According to the conversion of lignin liquefaction,the optimised catalyst for lignin liquefaction was Fe3O4@SiO2@Cu1.2Zn4 8Al-O at 320 ? for 1h.Fe3O4@SiO2@Cu1.2Zn4.8Al-O was used for catalytic liquefaction of lignin in supercritical methanol.The effects of the catalyst dosage,material/liquid ratio,reaction time and reaction temperature on lignin liquefaction were studied.The single factor experiment was found that the optimised catalyst was 10 mg in 3 mL methanol and 60 mg lignin,the increasing material/liquid ratio can reduce the conversion of lignin,while the increasing reaction time and reaction temperature can promote the liquefaction of lignin.In 24 full factorial design analyses with four kinds of reaction conditions,the reaction temperature is the most significant effect on the lignin liquefaction conversion.There are interactions only between the three factors which were reaction temperature A,reaction time B and material/liquid ratio D.The fitting formula of lignin supercritical methanol catalytic liquefaction by the software was got as follow:Conversion=61.53+8.17·A+1.92·B-0.99·C+3.125E-003·D+0.23·A· B-0.71·A·C-0.53·A·D-0.76·B·C+1.06·B·D-0.6·C·DLiquefaction products by using Fe3O4@SiO2@Cu1.2Zn4.8Al-O were various and complex.The main compositions were phenols,ketones,hydrocarbon and benzenes.Due to the break of ?-O-4 and hydrodeoxygenation,2',5'-dihydroxyacetophenone was the main ingredient which accounted for 24%-33%.