1. Key Laboratory of Coalbed Methane Resource & Reservoir Formation Process, Ministry of Education, China University of Mining & Technology, Xuzhou 221008, China
2. National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
3. School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China