Investigation Into Reaction Kinetics Of Several Important Combustion Intermediates

Efficient and clean utilization of fossil fuels is a critical aspect of achieving carbon peak and carbon neutrality goals.Developing combustion reaction kinetics models with predictive capabilities is an essential tool for comprehending the combustion process.The development of combustion reaction kinetics models involves various intermediate species and elementary reactions.Conducting combustion reaction kinetics research on important intermediate species can facilitate a better understanding of complex combustion networks.This article focuses on representative intermediate species,specifically unsaturated aldehydes and ketones in the low-temperature region,and polycyclic aromatic hydrocarbons（PAHs）in the high-temperature region.The selected typical compounds include 2-butenal,methacrolein,and methyl vinyl ketone for unsaturated aldehydes and ketones,and indene,naphthalene,anthracene,and phenanthrene for PAHs.Regarding experimental approaches,suitable experimental apparatus and research methods were selected.For unsaturated aldehydes,oxidation experiments were conducted in a jet-stirred reactor for 2-butenal and methacrolein,while methyl vinyl ketone was oxidized in a jetstirred reactor using 2,5-hexanedione as a precursor.In the case of PAHs,flow tube pyrolysis experiments were carried out using mixed and substituted aromatic hydrocarbons as precursors.This involved toluene mixed with propyne and propylene,onitrotoluene mixed with acetylene and ethylene,and chloromethyl naphthalene mixed with propyne and propylene.Based on experiments,this article discusses the effects of C=C double bonds and aldehyde groups on the low-temperature reaction activity and pollutant formation in the low-temperature oxidation intermediates of 2-butenal and methacrolein.The lowtemperature reaction activity of both butenal compounds mainly comes from the OH addition reaction experienced by the C=C double bond within the unsaturated aldehyde molecule.The bimolecular reaction between the resonance-stabilized fuel radical RCO and HO₂ is the source of early CO₂ formation.The different C3H5 produced by different aldehydes are the main source of differences in reaction activity.This article achieved satisfactory results using 2,5-hexanedione as a precursor of methyl vinyl ketone.The double carbonyl structure of 2,5-hexanedione makes methyl vinyl ketone the main product,and the C=C double bond and carbonyl group within methyl vinyl ketone allow for OH addition dissociation reactions and CH3 addition dissociation reactions,respectively,which produce acetaldehyde and pentanone,respectively.This study investigates the pyrolysis of toluene and propyne/propylene,which result in benzyl and propargyl radicals,respectively.The effects of adding propyne and propylene to toluene at different pressures are explored.Results show that the addition of propyne and propylene has minimal impact on fuel consumption but alters the consumption pathways of benzyl radicals.Synergistic effects are observed for the generation of indene and naphthalene.Reaction pathway analysis reveals a clear pressure dependence for the formation of these PAHs.Furthermore,by utilizing the characteristic of aryl radicals easily forming upon bond cleavage of substituted aromatic hydrocarbons,the ortho-nitrotoluene was used to generate ortho-methyl toluene,which then reacted with ethyne and ethene to produce indene and indane as well as their intermediates.The pyrolysis of 1-chloromethylnaphthalene and 2-chloromethylnaphthalene with propyne and propylene resulted in the formation of anthracene and phenanthrene,respectively.The selection of propyne and propylene did not significantly affect the product distribution,but the position of the methyl group had a substantial impact.