Effective tar removal in thermal decomposition is an urgent problem in biomass thermal utilization technology.The molecular structure properties of three typical model compounds(toluene,phenol and naphthalene)of biomass tar were studied by density functional theory,and the thermal decomposition process of tar model compounds was simulated by molecular dynamics based on ReaxFF(Reactive Force Field),which provided an in-depth study of the complex reaction process of tar thermal cracking at the molecular level.The influence of reaction temperature on pyrolysis characteristics was discussed.The pyrolysis mechanism of toluene,phenol and naphthalene,and the evolution process of intermediate radicals and gas products were studied in detail.The results show that the Mayer bond order of C—H bond is smaller than that of C—C bond,which is easier to break.The Mulliken charge of hydrogen in the side chain of aromatic ring is large,and it is more reactive.The thermal stability of the three tar model compounds is as follows:naphthalene＞phenol＞toluene.Phenol has highly active oxygen-containing functional groups,which make it easy to generate gas products during secondary cracking reaction,while toluene and naphthalene are easy to generate condensed aromatic hydrocarbons during secondary cracking reaction.The apparent activation energies by the first order kinetic pyrolysis of toluene,phenol and naphthalene are 314.03,362.39 and 396.74 kJ/mol,respectively.
关键词
生物质/焦油模型化合物/反应力场/分子模拟
Key words
biomass/tar model compounds/reactive force field/molecular simulation
维普
万方数据