Effect of different treatments on the performance of coal char for methane cracking to hydrogen
The cracking reaction of methane on Xiaolongtan (XLT) lignite coal as well as on treated coal chars,including water treated coal char,HCl-HF treated coal char and nitric acid treated coal char were investigated in a small quartz tube fixed bed.The initial conversion of methane on XLT coal char was 64.7％,and the initial conversion of methane on water treated coal char and nitric acid treated coal char were significantly increased to 78.5％ and 72.4％,respectively.Whereas the initial conversion of methane on HCl-HF treated coal char decreased to 54.1％,and the catalytic activity of the coal char was reduced.With the increasing reaction time,the methane cracking conversion and hydrogen yield also decreased gradually,indicating that different coal chars were gradually deactivated during the reaction process.The difference of coal chars before and after the reaction were characterized by SEM and specific surface area tester.The BET data showed that the specific surface area and microporous capacity of coal chars decreased and the average pore diameter increased after methane cracking,which was attributed to the reaction-generated carbon deposits clogging the micropores of the coal char.The SEM results showed that there was a significant generation of carbon deposits on the surface of the coal char after methane cracking,which ultimately led to the gradual decrease in the catalytic activity of the coal chars.
万方数据
维普
