College of Chemical and Biological Engineering,Shandong University of Science and Technology

褐煤和次烟煤等低阶煤具有较高的氧含量、挥发分和反应活性,适合用于制备酚类、酯类和酮类等高附加值含氧化合物,从而实现低阶煤的高效、低碳利用。热萃取是在温和条件下从低阶煤中选择性分离酚类、酯类和酮类化合物的重要手段,热萃取过程涉及化学键的断裂与重整。从低阶煤的结构、低阶煤的种类、溶剂类型、萃取温度和萃取方式等方面综述了热萃取分离低阶煤中酚类、酯类和酮类化合物进展,归纳了不同溶剂热萃取分离低阶煤中酚类、酯类和酮类化合物的机理,并总结了不同分析手段的应用现状。低阶煤的结构模型尚未得到统一,而被广泛接受的主客体模型表明可以通过定向打断煤分子间的共价键和非共价键实现含氧结构的分离。不同煤化程度的煤分子间化学键的种类和数目以及煤岩组分不同,因此不同种类的低阶煤萃取出的有机质有较大差异。与高沸点溶剂相比,低沸点溶剂萃取率适宜、容易与热萃取产物分离,更适合用于低阶煤的选择性热萃取,然而常规溶剂的特性单一,热萃取时具有一定的局限性,设计萃取率适宜(≤30%)和对含氧官能团选择性高的离子液体是未来的发展方向。此外,精密仪器的检测和热萃取产物的预处理等分析手段有利于充分认识热萃取过程,然而针对热萃取产物的成分复杂问题,有必要引入更为先进的分析手段并建立更低成本的分离提纯方法。为实际工业化应用,需要开发先进工艺与设备,并进行技术经济性评估。

Low-rank coals such as lignite and sub-bituminous coal have high oxygen content,volatile matter and reactivity,and aresuitable for using in the preparation of high value-added oxygenated chemicals such as phenols,esters and ketones,thus realizing the high-efficiency and low-carbon utilization of low-rank coals. Thermal extraction is the key method for the selective separation of phenols,estersand ketones from low-rank coals under mild conditions. The thermal extraction process involves the breaking and reforming of chemicalbonds. Research progress on thermal extraction to separate phenols,esters and ketones in low-rank coals was summarized in terms of thestructures and types of low-rank coal,solvent types,extraction temperatures and extraction methods. The mechanisms of selective thermalextraction of phenols,esters and ketones in low-rank coals by different solvents were summed up. The current status of the application ofdifferent analytical methods were also illustrated. Structural models of low-rank coals have not been unified,while the widely acceptedhost-guest model suggests that separation of oxygenated structures can be achieved by directed interruption of covalent and non-covalentbonds among coal molecules. The type and number of chemical bonds among coal molecules and the lithotype of coal are different fordifferent degree of coalification,thus the organic matter extracted from different types of low rank coals varies considerably. Comparedwith high-boiling solvents,low-boiling solvents are more suitable for selective thermal extraction of low-rank coals because of theirsuitable extraction yield and easy separation from thermal extraction products; however,conventional solvents exhibit a limited range ofproperties for thermal extraction. The design of ionic liquids with suitable extraction yield (≤30%) and high selectivity for oxygenated functional groups is the future development direction. In addition,analytical methods such as precision instrumentation and pre-treatment of thermal extraction products are useful for a full understanding of the thermal extraction process,however,it is necessary tointroduce more advanced analytical methods and establish cost-effective purification methods in view of the complexity of thecomposition of thermal extraction products. For practical industrial applications,advanced processes and equipment need to be developedand evaluated for techno-economics.

国家自然科学基金面上资助项目(22078177);新疆自治区重点研发任务专项资助项目(2022B03029-2)

梁鹏,郝美鲁,秦锡壮.低阶煤选择性热萃取及产物分析研究进展[J].洁净煤技术,2025,31(2):165−177.

LIANG Peng,HAO Meilu,QIN Xizhuang. Research progress on selective thermal extraction and product analysis of low-rank coal[J].Clean Coal Technology,2025,31(2):165−177.