关键词: 甲烷裂解, 氢, 固定床, 煤焦, 灰成分, 催化活性, 失活

Abstract:

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.

Key words: methane cracking, hydrogen, fixed-bed, coal char, coal ash, catalysis, deactivation