Using coal char

de-ashed coal char

coal ash and quartz as catalysts

cracking of methane is studied in a fixed bed reactor at 1123 K and atmospheric pressure. Methane conversion and hydrogen yield over fresh and de-ashed coal chars show certain difference. The initial methane conversion of 9.81% and hydrogen yield of 8.14% is achieved at 1123 K over coal ash. The results show that coal ash is of certain catalytic activity for methane cracking. The conversion and hydrogen yield over coal char decrease gradually with the reaction time

indicating the deactivation of coal char. Lignite char and de-ashed char before and after reaction were characterized by using scanning electron microscope and specific surface area determinator. The results shows that the surface area and micro-pore volume of coal chars decrease and average pore diameter increases after methane decomposition reaction

implying that the micro-pore could be blocking by deposition of carbon formed in methane cracking

and the part surface of coal char has been covered by carbon of deposition

which makes catalytic activity of coal char decrease gradually.