The Reaction Kinetic Studies Of Benzaldehyde Oxidation And Benzyl Alcohol Pyrolysis

Energy is an important source and guarantee to maintain the development and progress of human society.However,the exploitation and combustion of fossil energy not only provide energy,but also cause global environmental pollution.The main pollutants of combustion are polycyclic aromatic hydrocarbons（PAHs）and carbon black.Aromatic fuel is an important component of petroleum products and alternative fuels.Aromatics combustion can promote the formation of important combustion pollutants such as PAHs and carbon smoke,which is an ideal platform for the study of carbon black formation.The combustion of oxygen fuel can reduce the formation of carbon black and reduce the emission of pollutants.In this thesis,the study of the reaction kinetics of oxygenated aromatic hydrocarbons with simple structure and low boiling point,such as benzaldehyde（AlCHO）and benzyl alcohol（AlCH₂OH）are carried out which provides a new way to understand the formation mechanism of carbon black.The work content of this thesis is divided into five chapters.First of all,the importance of energy utilization is briefly described in Chapter 1.At present,Chinese energy structure is mainly based on fossil fuels.The exploitation and combustion of fossil energy not only provide energy,but also cause a series of environmental pollution problems.Model fuel and biomass fuel are widely concerned as two ways to solve energy and environmental problems.Then the research status of aromatic gasoline model fuel,biomass fuel and the combustion kinetics of oxygenated aromatic fuel at home and abroad is briefly introduced.According to the results of the review,the reaction kinetics of AlCHO and AlCH₂OH are studied in detail.Chapter 2 mainly introduces the detection technology,experimental device and dynamic simulation method used in the research process of this thesis.In this thesis,the synchrotron radiation vacuum ultraviolet photoionization mass spectrometry detection technology is used as the main combustion products and intermediates detection technology,and jet stirred reactor and flow tube reactor are used as the core reactor to carry out low-temperature oxidation experiment and pyrolysis experiment respectively.The methods of data acquisition and data processing are introduced.In the aspect of kinetic model,the development of CHEMKIN series software is introduced.Then,the calculation process,chemical kinetic mechanism and thermodynamic data of CHEMKIN-Pro software are briefly described.Finally,the main methods of sensitivity analysis and Rate-of-production（ROP）analysis are explained.In chapter 3,the oxidation of AlCHO at atmospheric pressure in a jet-stirred reactor at equivalence ratios of 0.4 and 2.0 within 475-900 K was studied.The intermediates and products were identified by synchrotron radiation photoionization and molecular beam mass spectrometry（MBMS）.Compared with previous studies,29 species such as formaldehyde（CH₂O）,methoxy（CH₃O）,hydrogen peroxide（H₂O₂）,ketene,furan,2,4-cyclopentadiene-l-one（C₅H₄O）,furfural,o-benzoquinone,1,4benzenediol and 1,4-cyclohex-2-enedione were newly detected.A kinetic model,involving 376 species and 2163 reactions was proposed,which reasonably predicted the experimental value.ROP analysis shows that H-abstractions reactions involving H atoms,OH,CH₃,HO₂ and phenoxy（Al0）radicals dominate the consumption of AlCHO.The decarbonylation reactions and ring opening reactions have a certain contribution to the promotion of oxidation process.AlO radicals,phenol（AlOH）and C₅H₄O are the significant intermediates for AlCHO oxidation.Sensitivity analysis shows that AlCHO+OH=AlCO+H₂O and H₂O₂（+M）=OH+OH（+M）are among the most sensitive reactions to promote the consumption of AlCHO at both conditions while the reaction AlOH+O2=AlO+HO₂ has strong inhibiting effect.AlCHO is more difficult to produce benzene（Al）compared with AICH₂OH oxidation while is easier to generate AlOH at the same condition.These results will enrich the understanding the oxidation mechanism and soot formation of AlCHO as a potential aromatic fuel.Chapter 4 presents the combustion kinetics of AICH₂OH.The pyrolysis of AlCH₂OH at 30 and 760 Torr was studied in a flow tube reactor.The synchrotron radiation photoionization and MBMS techniques were used to identify and quantify 39 intermediates and products including some small species,several monophenyl ring species,and a large number of PAHs.A comprehensive chemical kinetic reaction model involving 376 species and 2171 reactions was developed with reasonable prediction.According to the ROP analysis,the consumption of AlCH₂OH is mainly proceeded with the H-abstraction reactions with H atoms and OH radicals under both pressures.H-abstractions and unimolecular dissociation dehydrogenation reactions also play important roles in the subsequent formation of PAHs.Phenyl radicals,Al,and benzyl（AlCH2）radicals are important intermediates in the pyrolysis of AlCH₂OH,which provide various ways for the formation of PAHs.Sensitivity analysis presents that the most significant sensitive reaction of AICH₂OH consumption is the unimolecular initiation reaction by the C-O bond breaking from AlCH₂OH under both pressures.The combination of AlCH2 radicals with H atoms to form toluene（AlCH₃）has the most inhibiting influence on the AlCH₂OH consumption under both pressures,while it has little sensitive effects for the oxidation process of AlCH₂OH consumption.These results provide a theoretical basis for further study of the combustion chemical kinetics of AlCH₂OH and its application in bio alternative fuel.Chapter 5 briefly summarizes the research work of this thesis,and then looks forward to the future research of oxygenated aromatic fuels.