类煤分子热解转化的原位质谱研究

Coal is an important fossil fuel, whose inherent characteristics of solid complex mixtures have brought huge challenges to the efficient and clean coal utilization technologies. A deep understanding of coal structures and pyrolysis process would help a lot. However, the complex and transient thermal reactions of coal are not easily detected by the traditional analysis methods. Our research team has developed an in-situ pyrolysis system connected with high-resolution time-of-flight mass spectrometry (TOF-MS). In this TOF-MS, molecular-beam technique is applied, coupled with vacuum ultraviolet single-photon ionization (PI) and electron ionization (EI), which are all employed to quickly capture and identify the reactants, radicals, and products. In this project, with the in-situ pyrolysis TOF-MS system, several coal-based model molecules will be firstly investigated, distinguishing the key active species in their pyrolysis process and understanding their pyrolysis mechanism. Furthermore, the pyrolysis and structures of coals with different metamorphism degrees will be also explored, studying their main functional groups distribution and reactivity. This project is aimed to provide basic principles for understanding the pyrolysis conversion of coal with TOF-MS in-situ studies.

煤炭作为重要的化石燃料，其固有的复杂固体混合物特征使得煤炭高效清洁利用技术面临着严峻挑战，深入了解煤炭结构及其热解转化过程是解决问题的重要方向之一。然而，传统的分析测试及研究手段，难以了解煤的复杂的、瞬间变化的热反应行为。申请人所在研究团队自主研制了热解-高分辨飞行时间质谱原位检测系统，该系统利用分子束取样技术，及时电离热解自由基及产物，并简化离子传输过程，使离子快速进入检测系统，具有快速捕捉活性物种的能力。本项目将借助该原位质谱检测系统，结合真空紫外单光子电离和电子轰击电离双电离技术，深入研究含有不同官能团类煤分子的热解行为，厘清其热解过程中的关键活性物种。在此基础上，探究煤中主要官能团及弱键合作用的分布和结构特性在热场下随煤化程度的变化规律，为实现从分子水平认识煤中特征官能团及弱键合结构的分布及热场中反应特性提供基础。

本项目发展了一套类煤模型化合物分子热解转化过程的原位探测技术。以原位热解-高分辨飞行时间质谱为基础，对样品热解室进行优化设计和改进，并创造性地结合激光诱导超声解吸技术，成功地捕捉到多种类煤分子热解转化过程中的自由基和中间体，探索分子中官能团在热解过程中的转化、反应规律，为揭示复杂结构煤炭热解转化过程、研究煤炭结构及反应性提供原位研究基础。