Experimental Study On Catalytic Oxidation Of Biomass Tar Model Compound

Biomass is important to ease the energy crisis and environmental pollution for its fast growth,wide distribution and zero CO₂ emission.The development and utilization of biomass can help alleviate energy crisis and reduce environmental pollution.Biomass gasification is an effective and promising method to produce hydrogen,but tar is an unavoidable by-product during the conversion process.The experimental study on catalytic oxidation of biomass tar model compound is carried out using cupper and manganese based catalysts,and these catalysts are also characterized by several methods.Firstly,the response surface method?RSM?is used for the Cu-based catalyst preparations based on the calcination time,calcination temperature,and active component content as the independent variables and the carbon conversion efficiency of benzene as the response.The results indicate that both catalysts of Cu-1?600-4-30%?and Cu-2?800-8-10%?present the best catalytic performance.At a reaction temperature of 350?,the carbon conversion efficiencies of benenze reach 90.3%and 92.6%based on Cu-1 and Cu-2,respectively,which is consistant with the predicted values.The charaterizations of the catalysts indicate that the active substances of Cu-1 and Cu-2 are CuO and CuAl₂O₄,respectively,and the latter is implied to present a better catalytic performance.In addition,the optimized preparation conditions of Mn based catalysts are investigated by RSM.Experimental results of catalytic oxidation of benzene indicate that Mn-1?600-4-30%?and Mn-2?800-8-10%?catalysts have the best catalytic performance,and the benzene conversion efficiencies reach 93.2%and 92.6%respectively with Mn-1 and Mn-2 at350?,which are also consistent with the predicted values.Characterization of the catalysts shows that the active component of Mn-1 catalyst is Mn₂O₃,and the active component of Mn-2 catalyst is Mn₂AlO₄.Secondly,based on the study of Cu and Mn mono metal catalysts,the CuMn bimetallic catalyst is prepared,and its catalytic performance is studied by catalytic oxidation of benzene.The results show that when mass ratio of Cu/Mn is 3:1,two catalysts with the calcination temperature,calcination time,total content of active component,which are600-4-30%?CuMn-1?and 800-8-20%?CuMn-4?,have the best performance.In the catalytic oxidation experiment of benzene at 350?,the conversion efficiences of benzene are 96.6%and 93.3%using CuMn-1 and CuMn-4,respectively.According to the characterization analysis,the active component of CuMn-1 catalyst is Cu _XMn_YO₄,and the active components of CuMn-4 catalyst are CuMnO₂ and CuAl₂O₄.The experimental results of catalytic oxidation of benzene based on two catalysts of CuMn-1 and CuMn-4,show that the increase of temperature can increase the conversion efficiency of tar model.However,when the temperature is higher than 350?,the conversion efficiency is only slightly increased with the temperature.Benzene concentration has a significant effect on conversion efficiency.The lower the concentration is,the higher the conversion rate would be.The change of space velocity within 10000h^-1 has hardly effect on benzene conversion.Finally,a long-time experiment of benenze conversion is carried out on CuMn-1 and CuMn-4.The benzene conversion efficiency of CuMn-1 decrease slightly in the 8h reaction,while the CuMn-4 conversion efficiency decrease rapidly from 90%to 60%after 1h reaction.The results indicate that CuMn-1 exhibits a better anti-coking performance,and CuMn-1presents a better catalytic performance for the catalytic oxidation of methylnaphthalene and cresol.