Lucas Michael, Brotton Stephen J, Sprenger Jan A P, Finze Maik, Sharma Shiv K, Kaiser Ralf I
Department of Chemistry , University of Hawaii at Manoa , Honolulu , Hawaii 96822 , United States.
Institute for Inorganic Chemistry, Institute for Sustainable Chemistry & Catalysis with Boron (ICB) , Julius-Maximilians-Universität Würzburg , Am Hubland, 97074 Würzburg , Germany.
J Phys Chem A. 2019 Jan 31;123(4):780-795. doi: 10.1021/acs.jpca.8b11796. Epub 2019 Jan 15.
To develop the next generation of hypergolic, ionic-liquid-based fuels, it is important to understand the fundamental reaction mechanisms for the oxidation of ionic liquids (ILs). We consequently studied the oxidation of a levitated 1-butyl-3-methylimidazolium dicyanoborate ([BMIM][DCBH]) droplet by nitrogen dioxide (NO). The properties of [BMIM][DCBH], including short ignition-delay times, low viscosities, and a wide liquid temperature range, make the ionic liquid especially suitable as a component of a hypergolic fuel. The chemical modifications were monitored with Fourier-transform infrared (FTIR), Raman, and ultraviolet-visible spectroscopies. To identify changes induced by the oxidation, it was first necessary to assign vibrational modes to the FTIR and Raman spectra of unreacted [BMIM][DCBH]. The new features in the oxidized FTIR and Raman spectra could then be identified and assigned on the basis of the possible functional groups likely to form through addition with a nitrogen and an oxygen atom of nitrogen dioxide creating a new bond with the ionic liquid. The assignments suggest that organic nitro-compounds and boron-nitrogen and boron-oxygen containing compounds were produced. A large decrease in the intensity of some [DCBH] fundamental modes suggests the nitrogen dioxide molecule prefers to react with the anion over the cation.
为了开发下一代自燃型、基于离子液体的燃料，了解离子液体（ILs）氧化的基本反应机制非常重要。因此，我们研究了二氧化氮（NO）对悬浮的1-丁基-3-甲基咪唑二氰硼酸盐（[BMIM][DCBH]）液滴的氧化作用。[BMIM][DCBH]的特性，包括短点火延迟时间、低粘度和较宽的液体温度范围，使其特别适合作为自燃燃料的成分。通过傅里叶变换红外（FTIR）、拉曼和紫外可见光谱对化学变化进行监测。为了识别氧化引起的变化，首先需要将振动模式指定给未反应的[BMIM][DCBH]的FTIR和拉曼光谱。然后，基于可能通过与二氧化氮的氮原子和氧原子加成而形成的、与离子液体形成新键的官能团，来识别和指定氧化后的FTIR和拉曼光谱中的新特征。这些指定表明生成了有机硝基化合物以及含硼氮和硼氧的化合物。一些[DCBH]基模强度的大幅下降表明二氧化氮分子更倾向于与阴离子而非阳离子发生反应。
