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二甲基乙醚低温氧化中关键中间体(HOOCH2OC(=O)H)的分解反应机理
邢利利,张晓愿,王占东,李爽,张李东*
作者单位E-mail
邢利利 中国科学技术大学国家同步辐射实验室合肥230029  
张晓愿 中国科学技术大学国家同步辐射实验室合肥230029  
王占东 中国科学技术大学国家同步辐射实验室合肥230029  
李爽 中国科学技术大学国家同步辐射实验室合肥230029  
张李东* 中国科学技术大学国家同步辐射实验室合肥230029 zld@ustc.edu.cn 
摘要:
在QCISD(T)/CBS//B3LYP/6-311++G(d,p)方法的基础上计算了DME(二甲基乙醚)低温氧化的中间体HPMF(HOOCH2OC(=O)H)的分解路径, 并且结合变分过渡态理论及RRKM/主方程求解了温度以及压力依赖的动力学速率. 计算结果表明,除了脱OH的直接解离路径之外,HPMF将经过异构分解生成甲酸及CH2OO中间体. 新的动力学数据的结果证实了CH2OO 路径是不容忽略的. 这条分解路径将会降低整个模型的低温氧化活性. 同时从化学本质上去分析了HPMF的化学结构以及电子效应,进一步解释及验证了计算结果的合理性.
关键词:  HPMF,RRKM/主方程计算,低温氧化,DME,链分支
DOI:10.1063/1674-0068/28/cjcp1503053
分类号:
基金项目:
New Insight into Competition between Decomposition Pathways of Hydroperoxymethyl Formate in Low Temperature DME Oxidation
Li-li Xing,Xiao-yuan Zhang,Zhan-dong Wang,Shuang Li,Li-dong Zhang*
Abstract:
Hydroperoxymethyl formate is a crucial intermediate formed during the low-temperature oxidation of dimethyl ether. The decomposition pathways of HOOCH2OCHO were calculated at QCISD(T)/CBS//B3LYP/6-311++G(d,p) level. The temperature- and pressure-dependent rate constants are computed using microcanonical variational transition state theory coupled with the RRKM/master equation calculations. The calculations show that a pathway leads to the formation of formic acid and a Criegee intermediate does exist, besides the direct dissociation channel to OH and OCH2OCHO radicals. However, formation of the Criegee intermediate has never been considered as an intermediate in dimethyl ether combustion before. The computed rate constants indicate that the newly confirmed pathway is competitive to the direct dissociation route and it is promising to reduce the low-temperature oxidation reactivity. Also electronic effect of groups, e.g. -CHO and O atom, is taken into account. Moreover, Hirshfeld atomic charge and natural bond order analysis are performed to explain this phenomenon from a perspective of chemical nature.
Key words:  Hydroperoxymethyl formate, RRKM/master equation calculations, Low temperature oxidation, Dimethyl ether, Chain branching