Study On Catalytic Pyrolysis Performance Of Biomass Tar Through As-prepared Multi-mano Metal Assisted-char

As an important clean energy source today,biomass has great development potential.The tar generated in the pyrolysis process of biomass often causes great harm to the transmission pipeline,environment and human body.However,biomass tar is complex and difficult to remove,so tar is a difficult problem for biomass utilization.In this paper,nanoscale Ni-Fe materials were prepared by sol-gel method with biomass pyrolysis waste biochar as the carrier,and their catalytic pyrolysis performance to toluene,a tar analogue,was investigated.The catalytic pyrolysis mechanism of the two materials was studied by comparing the actual tar.The original biochar has abundant pore structure,and there are thin flask-shaped pores and open pores.Biochar has a specific surface area of 303.47m²/g and an average pore diameter of 4.21nm,showing good adsorption performance.After loading the metal,the specific surface area and pore diameter of the material become smaller,and the adsorption capacity decreases.XRD and XPS analysis results show that the supported metal is evenly dispersed on the surface of the biochar carrier and exists in the form of Fe₂O₃,NiO and NiFe₂O₄.With the increase of temperature,load,water vapor/biomass carbon ratio and gas residence time,the catalytic pyrolysis performance of toluene gradually improved and tended to be stable.The activity of the material began to decline after8h.The optimal reaction conditions were obtained based on the above experiments:the temperature was 800?,the loads of Ni and Fe were 6%,the water vapor/biomass carbon ratio was 1,and the gas residence time was 0.5s.At this point,the removal rate of toluene was 96.61%,and the relative content of H₂,CH₄,CO and CO₂ was 36.45%,0.029%,0.16%and 0.05%.Study the catalytic pyrolysis process of materials on toluene under optimal conditions:toluene generates small molecule gas products?H₂,CO,CO₂,CH₄?under the catalytic pyrolysis of materials,and produces carbon deposition on the surface of biochar.After catalytic pyrolysis,the pore size of the material becomes smaller,the pore size is blocked by ash and carbon deposition,and the adsorption capacity further decreases,and the active metal components are reduced to some Ni and Fe elements.Studies on catalytic pyrolysis reaction of toluene and steam gasification reaction kinetics of biochar have shown that they conform to the first-order global kinetic model and the unreacted shrinkage nuclear model respectively.The catalytic pyrolysis effect and catalytic pyrolysis process of the actual tar were studied under optimal conditions.After catalytic pyrolysis by char,Fe-6/char,Ni-6/char and Ni-6-Fe-6/char,86 kinds of organic compounds were identified in tar.After catalytic pyrolysis of char,Fe-6/char,Ni-6/char and Ni-6-Fe-6/char,the content of single aromatic hydrocarbons increased,while the content of heterocyclic,light polycyclic aromatic hydrocarbons and heavy polycyclic aromatic hydrocarbons decreased.After the tar molecules are catalyzed to crack,the large polycyclic aromatic hydrocarbons and heterocyclic compounds in the tar will be converted into small monocyclic aromatic hydrocarbons.