Hydrogen production by methane decomposition over coal char

摘要

The aim of this work was to use low-cost coal char without further activation as a catalyst for hydrogen production by methane decomposition in a fixed bed reactor. The kinetic of methane decomposition was investigated preliminarily and the changes of surface properties were also studied. The results show that the lignite char has a much higher activity in methane decomposition than bituminous and anthracite ones and its initial rate is not less than that of activated carbon under the same condition. The temperature of the preparation of char has an effect only on the initial activity of char in methane decomposition, while the reaction temperature influences the activity and the stability of char greatly. The ash in coal also has little effect on the catalytic activity of char in methane decomposition. The initial reaction order of methane decomposition over coal char is 0.5 which is the same as that over activated carbon. And the activation energy is about 89-105 kJ mol~(-1) which is much lower than the methane C-H bond dissociation energy of 440 kJ mol~(-1). Methane decomposition over coal chars occurs mainly within its micropores. Using low-cost coal char as a catalyst is a promising method for hydrogen production by methane decomposition both economically and environmentally.