Hydrogen production by methane cracking over a bed of four different Chinese coal chars has been studied using a fixed-bed reactor system operating at atmospheric pressure and 1123 K.The chars were prepared by pyrolysing the four parent coals of different ranks,namely,Jin-cheng anthracite,Bin-xian bituminous coal,Xiao-long-tan lignite and Sheng-li lignite,in nitrogen in the fixed-bed reactor operating at different temperatures and pyrolysis times.Hydrogen was the only gas-phase product that was detected during the experiments.Both methane conversion and hydrogen yield decreased with increasing reaction time.The lower the coal rank,the greater the catalytic effect of the char on the methane cracking.A higher catalytic activity was observed for the Xiao-long-tan lignite char prepared at 973 K.The coal chars had legible faces and sharp apertures before being subjected to methane cracking.The surfaces and pores of coal chars were covered with the carbon produced by the methane cracking as evident in the SEM images.The catalytic activity of the coal chars were reduced by the carbon deposition.The results of BET surfaces areas of the coal chars revealed that the presence of micropores in the chars was not an exclusive reason for catalysing methane cracking
coal char:hydrogen:methane cracking
Ling Wei Yisheng Tan Yizhuo Han Qingde Zhang Hongjuan Xie Jiantao Zhao Jinhu Wu Dongke Zhang
Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,China Graduate School of Chin Qingdao Institute of Bioenergy and Bioprocessing Technology,Chinese Academy of Sciences,Qingdao 2661 Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,China Qingdao Institute of Bioenergy and Bioprocessing Technology,Chinese Academy of Sciences,Qingdao 2661 Qingdao Institute of Bioenergy and Bioprocessing Technology,Chinese Academy of Sciences,Qingdao 2661