Mechanistic Study Of The Reactions Of Ethanol And Formaldehyde With Simple Peroxides In Low Temperature

In the process of hydrocarbon fuel combustion,the alcohol composition has great influence on its combustion and emission characteristics.In this paper,the coupling mechanism of ethanol and its intermediate(formaldehyde)and n-heptane intermediate(methyl peroxide,hydrogen peroxide)was studied and analyzed in detail by using the theory of quantum chemistry to improve the low temperature coupling mechanism of alcohol components in the process of hydrocarbon fuel oxidation.Mechanism studies of Hydrogen Abstraction of reaction C₂H₅OH with XO₂(X=CH₃,H)were investigated at the MP2/aug-cc-p VTZ l theory over a temperature range of 300–1500 K.Complex species were identified for local minimum.Basing on the optimized geometries,the energies for all species were calculated with CCSD(T)method and T1 diagnostic tests have been performed for all species.There are three possible hydrogen abstraction channels for the title reaction of XO₂(X=CH₃,H)+CH₃CH₂OH reaction.The channels of hydrogen abstraction producing XO₂H(X=CH₃,H)and 1-hydroxy-ethoxy radical(CH₃CHOH)was identified as dominant channel.During the low-temperature region,the tunneling effect plays an major role and the channel producing CH₃CHOH is predominant at the low-temperature,and all possible hydrogen abstractions have positive temperature dependence.The geometries of all species alone the minimum energy path of channels were calculated at the M06-2X/6-311++G(d,p)level of theory.The reaction of CH₃O₂with CH₂O has been investigated by the CCSD(T)/cc-p VTZ method based on the geometries of stationary points.Theoretically,there are three possible product channels and The channels of hydrogen abstraction was identified as dominant channel.The hydrogen path will first form a low potential well after the reaction starts,while the other two will not form a reaction complex but directly cross the high barrier transition state and form a reaction intermediate with unstable chemical properties.The rate constants for hydrogen abstraction have positive temperature dependence in the calculated temperature range,and the tunneling effect plays an important role in the low temperature region.The calculation accuracy of rate coefficient for the reaction of the dominant reaction path is high,and the error between the calculation result and the experimental result is less than 3.5%.