Characteristic Analysis And Degradation Of Biomass Pyrolysis Tar

As a by-product of biomass pyrolysis process,biomass tar is a renewable resource that can be converted into liquid fuel.However,due to its high water content,high relative molecular weight,strong acidity and high organic oxygen content,it has the disadvantages of low calorific value,unstable nature,corrosion-prone clogging equipment and environmental pollution.In this paper,corn straw and pine sawdust represented by agricultural waste and plastic and rubber particles represented by municipal solid waste were selected as experimental materials.The effects of biomass types,temperature and coke of corn straw with Fe₂O₃,Na₂CO₃ and CaO as different carbon-based catalysts on the yield,composition and composition of biomass pyrolysis tar were investigated,and the characteristics of biomass tar were analyzed.The degradation of tar by biomass carbon-based catalysts was investigated.（1）Four different biomass were pyrolyzed at 700℃.The liquid phase products were analyzed.It was found that the oxygen-containing functional groups and aromatic hydrocarbon functional groups in the pyrolysis tar of corn straw and pine wood were the main components,and the oxygen-containing functional groups were the most abundant.The main components in the pyrolysis tar of plastics and rubber were aliphatic hydrocarbons.The results of GC-MS showed that the contents of monocyclic aromatic compounds and heterocyclic compounds furans and pyrazoles in pyrolysis tar of corn straw and pine wood were higher.The highest content of non-aromatic ring oxides in pine tar is 37.45%.The contents of aliphatic compounds in plastics and rubber are 42.52%and 20.05%respectively.（2）Two typical biomass,corn straw and plastics,were selected to conduct pyrolysis experiments at different temperatures.The results showed that tar yield tended to decrease with the increase of temperature.Increased temperature could promote the decomposition of internal components of pyrolysis products.The pyrolysis tar yield of corn straw decreased by 20.23%when the temperature increased from 500℃to 800℃,and that of plastics decreased by 13.46%from 550℃to 750℃.The contents of functional groups in pyrolysis tar of corn straw were:oxygen functional group>aromatic functional group>aliphatic functional group.The content of oxygen-containing functional groups was up to 54.84%at 500℃.The types of functional groups in plastic pyrolysis tar were the same as those in corn straw tar,and there was no obvious change in the content of various functional groups with the increase of temperature.（3）Added 10%Fe₂O₃,Na₂CO₃ and CaO into corn straw coke as different catalysts to study the degradation effect of carbon-based catalysts on corn straw and plastic tar respectively.The results showed that carbon-CaO has the strongest degradation effect on corn straw pyrolysis tar,and the lowest tar yield can be reduced to 20.01%at 800℃.The strongest degradation effect on oxygen-containing functional groups under the action of carbon-CaO,and the content decreased from 44.70%without catalysis to 11.36%.Carbon-Na₂CO₃ has the strongest effect on the degradation of tar from plastic pyrolysis,and the liquid product yield of plastics is the lowest under the catalytic condition of 10%carbon-Na₂CO₃ at 750℃.The addition of Na₂CO₃ and CaO catalysts has obvious deoxidation effect on pyrolysis oil,thus reducing the oxygen content of pyrolysis oil.