Low-rank coal, a widely available fossil fuel with abundant reserves, has significant potential for clean energy conversion. Pyrolysis is an effective method for utilizing low-rank coal sustainably. This study summarizes the characteristics of low-rank coal and provides an in-depth analysis of its pyrolysis process and product characteristics. It reveals that the low quality of pyrolysis products is a key factor limiting the development of low-rank coal pyrolysis technology. To address this issue, three product control strategies are proposed to enhance product quality and efficiency. The application of these strategies can effectively optimize the pyrolysis process and improve product performance, thereby expanding its potential applications in energy, chemicals, environmental protection, and new materials. Additionally, the study explores the broad application prospects of low-rank coal pyrolysis products, demonstrating the significant role of low-rank coal pyrolysis technology in optimizing energy structures and promoting environmental protection. The study provides solutions to the key bottlenecks constraining the development of pyrolysis technology for this low-rank coal, which is of great value for optimizing the energy structure and promoting environmental protection. 

Lijun Bai. Advances in Low-Rank Coal Pyrolysis: Strategies for Optimizing Product Quality and Expanding Applications in Clean Energy and Environmental Protection. Nature Environmental Protection (2025), Vol. 6, Issue 1: 36-44. https://doi.org/10.38007/NEP.2025.060104.

[1]Huijuan Song, Guangrui Liu, Jinzhi Zhang, and Jinhu Wu. Pyrolysis Characteristics and Kinetics of Low Rank Coals by Tg-Ftir Method. Fuel Processing Technology. (2017) 156: 454-60.https://doi.org/10.1016/j.fuproc.2016.10.008.

[2]Jianglong Yu, Arash Tahmasebi, Yanna Han, Fengkui Yin, and Xianchun Li. A Review on Water in Low Rank Coals: The Existence, Interaction with Coal Structure and Effects on Coal Utilization. Fuel Processing Technology. (2013) 106: 9-20.https://doi.org/10.1016/j.fuproc.2012.09.051.

[3]He Yang, Li Sufen, Fletcher Thomas H., Dong Ming, and Zhou Weishi. Simulation of the Evolution of Pressure in a Lignite Particle during Pyrolysis. Energy & Fuels. (2014) 28(5): 3511-18.https://doi.org/10.1021/ef500584q.

[4]Harold Schobert. Introduction to Low-Rank Coals: Types, Resources, and Current Utilization. In Low-Rank Coals for Power Generation, Fuel and Chemical Production, edited by Zhongyang Luo and Michalis Agraniotis, 3-21: Woodhead Publishing, 2017.

[5]Xu Zhang, Libin Wang, Xianfeng Pei, Yan Wang, and Zhou Qi. Research Progress and Key Technology of Improving Coal Tar Yield and Quality by Coal Pyrolysis. Coal Science and Technology. (2019) 47(03): 227-33.https://doi.org/10.13199/j.cnki.cst.2019.03.034.

[6]Sunel Kumar, Yong He, Faisal Mahmood, Yanqun Zhu, Jianzhong Liu, Zhihua Wang, and Shuang Wang. Catalytic Influence of Iron Oxide (Fe2o3) on Coal Pyrolysis and Char Combustion at Various Temperatures. Materials Today Communications. (2024) 39: 108982.https://doi.org/10.1016/j.mtcomm.2024.108982.

[7]Mininni G., Braguglia C. M., and Marani D.. Partitioning of Cr, Cu, Pb and Zn in Sewage Sludge Incineration by Rotary Kiln and Fluidized Bed Furnaces. Water Science and Technology. (2000) 41(8): 61-68.https://doi.org/10.2166/wst.2000.0143.

[8]Qiumin Zhang, Nie Fan, and Meng Tao. Pyrolysis of Low-Rank Coal: From Research to Practice. In Pyrolysis, edited by Mohamed Samer. Rijeka: IntechOpen, 2017.

[9]Manouchehr Haghighat, Majidian Nasrollah, Hallajisani Ahmad, and Samipourgiri Mohammad. Production of Bio-Oil from Sewage Sludge: A Review on the Thermal and Catalytic Conversion by Pyrolysis. Sustainable Energy Technologies and Assessments. (2020) 42: 100870.https://doi.org/10.1016/j.seta.2020.100870.

[10]Bing Zhao, Jing Jin, Shang Li, Dunyu Liu, Ruipu Zhang, and Haoran Yang. Co-Pyrolysis Characteristics of Sludge Mixed with Zhundong Coal and Sulphur Contaminant Release Regularity. Journal of Thermal Analysis and Calorimetry. (2019) 138(2): 1623-32.https://doi.org/10.1007/s10973-019-08300-x.

[11]Petrakis L., and Grandy D. W. Free Radicals in Coals and Synthetic Fuels. United States: Elseivier Science Publishers Co. Inc.,New York, NY, 1984.

[12]Chongyang Dai, Yishui Tian, Erfeng Hu, Moshan Li, Dazhao Ma, and Shao Si. Research on Co-Pyrolysis Characteristics of Biomass and Low-Rank Coal and Its Technical Progress. Acta Energiae Solaris Sinica. (2021) 42(12): 326-33.https://doi.org/10.19912/j.0254-0096.tynxb.2021-0287.

[13]Saxena S. C. Devolatilization and Combustion Characteristics of Coal Particles. Progress in Energy and Combustion Science. (1990) 16(1): 55-94.https://doi.org/10.1016/0360-1285(90)90025-X.

[14]Junhong Wu, Jianzhong Liu, Xu Zhang, Zhihua Wang, Junhu Zhou, and Cen Kefa. Chemical and Structural Changes in Ximeng Lignite and Its Carbon Migration during Hydrothermal Dewatering. Fuel. (2015) 148: 139.https://doi.org/10.1016/j.fuel.2015.01.102.

[15]Ahmed I. I., and K. Gupta A. Experiments and Stochastic Simulations of Lignite Coal during Pyrolysis and Gasification. Applied Energy. (2013) 102: 355-63.https://doi.org/10.1016/j.apenergy.2012.07.049.

[16]Qianjin Dai, Qiang Liu, Murat Yılmaz, and Xueyang Zhang. Co-Pyrolysis of Sewage Sludge and Sodium Lignosulfonate: Kinetic Study and Methylene Blue Adsorption Properties of the Biochar. Journal of Analytical and Applied Pyrolysis. (2022) 165: 105586.https://doi.org/10.1016/j.jaap.2022.105586.

[17]Zhengfu Peng, Xiaojun Ning, Guangwei Wang, Jianliang Zhang, Yanjiang Li, and Chunchao Huang. Structural Characteristics and Flammability of Low-Order Coal Pyrolysis Semi-Coke. Journal of the Energy Institute. (2020) 93(4): 1341-53.https://doi.org/10.1016/j.joei.2019.12.004.

[18]Dimple Mody Quyn, Hongwei Wu, and Chunzhu Li. Volatilisation and Catalytic Effects of Alkali and Alkaline Earth Metallic Species during the Pyrolysis and Gasification of Victorian Brown Coal. Part I. Volatilisation of Na and Cl from a Set of Nacl-Loaded Samples. Fuel. (2002) 81(2): 143-49.https://doi.org/10.1016/S0016-2361(01)00127-2.

[19]Jinquan Wang. Reaserch on Gasification of Coal Catalyzed by Molten Salts. master, North China Electric Power University, 2008. Cnki.

[20]Tingyu Zhu, Shouyu Zhang, Jiejie Huang, and Yang Wang. Effect of Calcium Oxide on Pyrolysis of Coal in a Fluidized Bed. Fuel Processing Technology. (2000) 64(1-3): 271-84.https://doi.org/10.1016/S0378-3820(00)00075-8.

[21]Xindong Wang, and Jiangyin Lu. Research Advancement on Catalytic Pyrolysis Control of Pyrolysis Products. Shandong Chemical Industry. (2012) 41(05): 29-33.https://doi.org/10.19319/j.cnki.issn.1008-021x.2012.05.009.

[22]Jun Zhou, Zhe Yang, Xiaofeng Liu, Lei Wu, Yuhong Tian, and Zhao Xicheng. Study on Microwave Co-Pyrolysis of Low Rank Coal and Circulating Coal Gas. Spectroscopy and Spectral Analysis. (2016) 36(02): 459-65.

[23]Chenkai Gu, Jing Jin, Ye Li, Ruiyang Li, and Dong Bo. Effects of Co2 Atmosphere on Low-Rank Coal Pyrolysis Based on Reaxff Molecular Dynamics. RSC Advances. (2023) 3): 1935-42.https://doi.org/10.1039/D2RA07853H.

[24]WeiChun Xu, and Tomita Akira. The Effects of Temperature and Residence Time on the Secondary Reactions of Volatiles from Coal Pyrolysis. Fuel Processing Technology. (1989) 21(1): 25-37.https://doi.org/10.1016/0378-3820(89)90012-X.

[25]Zhaorui Chen, Qinhui Wang, Zhihang Guo, Zhongyang Luo, Xin Jia, and Fang Mengxiang. Influence of the Residence Time of Gases Pyrolyzed on the Pyrolytic Products of Typical Bituminous Coal. Journal of Engineering for Thermal Energy and Power. (2015) 30(05): 756-61+826-27.https://doi.org/10.16146/j.cnki.rndlgc.2015.05.027.