Article pubs.acs.org/EF
Powder-Activated Semicokes Prepared from Coal Fast Pyrolysis: Influence of Oxygen and Steam Atmosphere on Pore Structure Zhen Zhang,† Tao Wang,† Liu Ke,† Xiqiang Zhao,†,‡ and Chunyuan Ma* †
National Engineering Laboratory of Coal-Fired Pollution Reduction, Shandong University, No. 17923 Jingshi Road, Jinan 250061, China ‡ Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Ministry of Education of China, Chongqing University, Chongqing 400044, China ABSTRACT: The present work reveals the information about pore characterizations of powder-activated semicoke (PASC) derived from coal fast pyrolysis in oxygen and steam atmosphere. Nitrogen adsorption measurements were performed on the samples prepared by fast pyrolysis in different pyrolysis atmospheres to analyze and characterize the nature of the pore structure. Two evolution paths of pore structure were identified during the activated semicoke (ASC) preparation due to the effect of oxygen. The results showed that type I and type IV nitrogen adsorption isotherms with type A and type B hysteresis loops are present in these samples prepared under oxygen presence atmosphere, so micropores and mesopores may be predominant. In contrast, PASC prepared in oxygen absence atmosphere presents obvious mesoporous structure. The presence of oxygen and steam in pyrolysis atmosphere is beneficial to the increase of the total pore volume and specific surface area. However, too high of oxygen and steam concentration could destroy some micropores to decrease the surface area. Oxygen concentration during the PASCs preparation has a dominating influence on pore structures, and steam can assist oxygen to achieve precise control of the PASCs’ pore structure. for the preparation of PASCs, a low heating rate (
