Abstract The effects of NO addition (1000, 2000 ppm) on the low-temperature oxidation of dimethyl ether (DME) and dimethoxymethane (DMM), as particular cases of oxymethylene ethers (OMEn) with n = 0 and 1, have been investigated in a plug-flow reactor at near-atmospheric pressure in a temperature range of 400–1000 K. An in-situ electron ionization molecular-beam mass spectrometer (EI-MBMS) was used to measure the reactants, intermediates, and products, with particular attention on nitrogenous species that were scarcely detected previously. Explorative modeling with published mechanisms was performed, indicating the necessity of further model development. Potential kinetic fuel/NO interactions are discussed based on the experimental observations. The results reveal an overall inhibiting effect of NO addition on DME reactivity in the low-temperature regime, but a pronounced promoting effect at higher temperatures. For DMM, a similar temperature-dependent effect of NO was observed, but only for high NO concentration (2000 ppm). NO addition significantly suppresses the formation of hydrocarbon intermediates for both DME and DMM, but remarkably promotes the formation of methyl formate and methanol for DME. Several nitrogenous species were detected upon NO addition. The interactions of NO + HO2 and NO + OH, together with the regeneration routes of NO, are thought to be influential for both DME and DMM oxidation, while the significance of the NO + RO2 (R, fuel radical) reaction depends on the reactivity of the respective RO2 radical of DME and DMM. These results contribute to the understanding of OMEn/NO interactions and serve as a basis for further model development by providing new and detailed speciation data for DME/NO and DMM/NO oxidation.

中文翻译：

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NO对活塞流反应器中二甲醚和二甲氧基甲烷氧化的抑制和促进作用

摘要 作为 n = 0 和 1 的甲醛醚 (OMEn) 的特殊情况，研究了 NO 添加 (1000, 2000 ppm) 对二甲醚 (DME) 和二甲氧基甲烷 (DMM) 低温氧化的影响。温度范围为 400-1000 K 的接近大气压的活塞流反应器。 原位电子电离分子束质谱仪 (EI-MBMS) 用于测量反应物、中间体和产物，特别是关注以前几乎没有发现的含氮物种。使用已发布的机制进行了探索性建模，表明进一步开发模型的必要性。基于实验观察讨论了潜在的动力燃料/NO 相互作用。结果表明，在低温状态下，NO 添加对 DME 反应性有总体抑制作用，但在较高温度下具有显着的促进作用。对于 DMM，观察到 NO 的类似温度依赖性影响，但仅适用于高 NO 浓度（2000 ppm）。NO添加显着抑制了二甲醚和二甲醚的烃中间体的形成，但显着促进了二甲醚的甲酸甲酯和甲醇的形成。添加 NO 后检测到几种含氮物质。NO + HO2 和 NO + OH 的相互作用，以及 NO 的再生路线，被认为对 DME 和 DMM 氧化都有影响，而 NO + RO2（R，燃料自由基）反应的重要性取决于反应性DME 和 DMM 各自的 RO2 自由基。