Liu Tao, Zhao Jingkun, Zhang Xiaodong
Collage of Chemistry and Chemical Engineering, Qingdao University, Qingdao266071, China.
ACS Omega. 2023 Jan 17;8(4):4419-4428. doi: 10.1021/acsomega.2c08225. eCollection 2023 Jan 31.
Realizing the directional conversion of volatile matter (especially tar) from catalytic pyrolysis of low-rank coal (LRC) and reducing the consumption of catalysts have been considered great challenges for the classified utilization of LRC. In order to realize this aim, in this work, combined and catalytic pyrolyses (IECPs) were first applied to the conversion of low-rank coal. A small amount of ZSM-5 (5 wt %) was mixed with LRC to regulate the pyrolysis reaction, and then a large amount of ZSM-5 (100 wt %) was used to control the volatiles produced by pyrolysis. The IECPs (550 °C) of LRCs were investigated in a fixed-bed reactor. For three LRCs with different coalification degrees, IECPs could obviously reduce the complexity of the tar components. When ZSM-5 dosage was 5 wt % and the reaction temperature was 550 °C, the relative content of BTX in ZT, BS, and JY tar increased from 20.23, 15.86, and 14.59% to 84.79, 77.26, and 50.11 area %, respectively. The relative contents of aliphatic hydrocarbons with a complex composition and a low price decreased from 67.84, 34.47, and 33.89 area % to 3.02, 1.81, and 7.60 area %, respectively. The catalysis mechanism was explored by TG-FTIR spectroscopy, which revealed that ZSM-5 had a great influence on the migration of aliphatic hydrocarbon intermediates in IECP, such that large amounts of aliphatic hydrocarbons of complex composition produced by IECP tended to be converted to small molecular substances (gas) or aromatic hydrocarbons (tar). It will provide a new theoretical support for the staged utilization of LRC.
实现低阶煤催化热解中挥发物（尤其是焦油）的定向转化并降低催化剂消耗，一直被认为是低阶煤分级利用面临的巨大挑战。为实现这一目标，在本工作中，首次将组合催化热解（IECPs）应用于低阶煤的转化。将少量的ZSM-5（5 wt%）与低阶煤混合以调节热解反应，然后使用大量的ZSM-5（100 wt%）来控制热解产生的挥发物。在固定床反应器中研究了低阶煤在550℃下的IECPs。对于三种不同煤化程度的低阶煤，IECPs可明显降低焦油成分的复杂性。当ZSM-5用量为5 wt%且反应温度为550℃时，ZT、BS和JY焦油中BTX的相对含量分别从20.23%、15.86%和14.59%增加到84.79%、77.26%和50.11面积%。组成复杂且价格低廉的脂肪烃的相对含量分别从67.84%、34.47%和33.89面积%降至3.02%、1.81%和7.60面积%。通过TG-FTIR光谱探索了催化机理，结果表明ZSM-5对IECP中脂肪烃中间体的迁移有很大影响，使得IECP产生的大量复杂组成的脂肪烃倾向于转化为小分子物质（气体）或芳烃（焦油）。这将为低阶煤的分级利用提供新的理论支持。
