RESEARCH ARTICLE Catalytic effect of alkali and alkaline earth metals in different occurrence modes in Zhundong coals Dingcheng Liang 1 | Qiang Xie 1 | Huabing Zhou 1 | Mingshun Yang 1,2 | Junya Cao 1 | Jun Zhang 1 1 School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), D11 Xueyuan Road, Haidian District, Beijing 100083, China 2 Datang International Chemical Technology Research Institute Co., Ltd., Beijing, China Correspondence Qiang Xie, School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), D11 Xueyuan Road, Haidian District, Beijing 100083, China. Email: dr‐xieq@cumtb.edu.cn Funding information National Key Basic Research Program of China, Grant/Award Number: 2014CB238905 Abstract Two Zhundong coals, Nanlutian coal and Wucaiwan coal, were pretreated by a sequential extraction; alkali and alkaline earth metals (AAEMs) in different occurrence modes were separated from the coal samples. The contents and compositions of AAEMs in coal were investigated, and then a kinetic model was used to quantify their catalytic behavior. Experimental results show that the content of water‐soluble AAEMs is high and that these AAEMs are composed mainly of NaCl and other sodium species. After removing these AAEMs from the Nanlutian coal and the Wucaiwan coal, the activation energy required for gasification increases by 7.679 and 4.035 kJ mol -1 , respectively. Some of the sodium, potassium, calcium, and magnesium species exist in ion‐exchangeable form, but the content is low. When the ion‐exchange- able AAEMs were removed, the activation energy increases by 5.117 and 1.400 kJ mol -1 , respectively. The content of acid‐soluble AAEMs is high and com- posed mainly of calcium and magnesium salts. After removing these AAEMs, the activation energy was increased by 2.002 and 0.537 kJ mol -1 , respectively. Finally, the content of insoluble AAEMs is very high, and this fraction is com- posed mainly of silicates and aluminosilicates. As these AAEMs are stable, their catalytic effect could be ignored. KEYWORDS alkali and alkaline earth metals (AAEMs), catalytic performance, occurrence modes, Zhundong coal 1 | INTRODUCTION The Zhundong coalfield, located in the Xinjiang Uygur Autonomous Region, is the largest integrated basin in China and includes a huge coal reserve of 390 Gt. 1 Zhundong coal is a promising fuel for power plants because of its high volatility and low ash and sulfur con- tents. Unfortunately, severe slagging, fouling, and ash deposition occur inside furnaces and convective passes when Zhundong coal is burned. 2 The high concentration of alkali and alkaline earth metals (AAEMs) has been found to be responsible for these problems. Additionally, AAEMs show catalytic behavior and can increase the gas- ification reaction rate. Besides, Zhundong coal, with its high reactivity, is also a promising feedstock for gasifica- tion. Therefore, AAEMs in the Zhundong coal have attracted much attention recently. Revealing the mode of occurrence and the role of AAEMs is a prerequisite for clean use of Zhundong coal. Normally, these properties are determined by the sequential extraction method, which is four‐step proce- dure using four types of extraction agent: deionized Received: 18 January 2018 Revised: 7 March 2018 Accepted: 8 March 2018 DOI: 10.1002/apj.2190 Asia‐Pac J Chem Eng. 2018;e2190. https://doi.org/10.1002/apj.2190 © 2018 Curtin University and John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/apj 1 of 13