Abstract Thermogravimetry coupled with electron impact mass spectrometry (TG-EI MS) was used to investigate the evolutions of gases and small molecular weight oxygenates during the pyrolysis of a raw lignite and a potassium (K)-impregnated lignite. By clarifying the effects of ionization on the fragmentations of various compounds, it was found that a low ionizing energy of 20 eV was better for detecting oxygenates. The study further proposed a unique approach of the installment of a cold trap between the TG-MS interfaces. This vapor trapping approach is useful to distinguish between some compounds of equal mass in terms of their different boiling points. The real-time release of various oxygenates during the pyrolysis of the raw lignite and the K-impregnated lignite were detected. It was found that some highly volatile oxygenates such as formic acid (46 m/z), acetone (58 m/z) and butanone (72 m/z) started to release at a temperature of 200 °C or lower. Many oxygenates such as furan (68 m/z), methylfuran (82 m/z), cyclopentenone (82 m/z), cyclopentanone (84 m/z), furfural (96 m/z), dimethylfuran (96 m/z), cyclohexenone (96 m/z) and dimethoxyphenol (154 m/z) could be explained as the products degraded from the preserved woody components in this low-maturity lignite. The K impregnation overall facilitated the formations of oxygenates, while it had an inhibitory effect on the formation of CO and an insignificant effect on the formations of some oxygenates such as acetic acid and phenol. The curves of differential thermogravimetry (DTG) were deconvoluted to correspond to the staged release characteristics of main gases and various oxygenates.

中文翻译：

---

褐煤热分解的热重-质谱表征，并关注小分子量含氧化合物的演变

摘要 热重分析与电子轰击质谱联用 (TG-EI MS) 用于研究原始褐煤和钾 (K) 浸渍褐煤热解过程中气体和小分子量含氧化合物的释放。通过阐明电离对各种化合物碎裂的影响，发现 20 eV 的低电离能更适合检测含氧化合物。该研究进一步提出了一种在 TG-MS 界面之间安装冷阱的独特方法。这种蒸汽捕集方法可用于根据沸点不同来区分一些相同质量的化合物。检测到在原始褐煤和经钾浸渍的褐煤热解过程中各种含氧物的实时释放。发现一些高挥发性含氧化合物，如甲酸 (46 m/z)、丙酮 (58 m/z) 和丁酮 (72 m/z) 在 200 °C 或更低的温度下开始释放。许多含氧化合物，例如呋喃 (68 m/z)、甲基呋喃 (82 m/z)、环戊烯酮 (82 m/z)、环戊酮 (84 m/z)、糠醛 (96 m/z)、二甲基呋喃 (96 m/z) )、环己烯酮 (96 m/z) 和二甲氧基苯酚 (154 m/z) 可以解释为从这种低成熟度褐煤中保存的木质成分降解的产物。K浸渍总体上促进了含氧物的形成，同时对CO的形成有抑制作用，对某些含氧物如乙酸和苯酚的形成影响不显着。