Methane cracking over lignite char

Methane cracking over a lignite char was studied in a fixed bed reactor. The experiments were performed at temperature range from 1123K to 1273K and atmospheric pressure. The total flow rate was 250mL/min with methane concentrations of 10%, 15% and 20%, respectively. The lignite char shows a significant catalytic activity on methane cracking. The maximum conversion of methane of 99.5% is achieved at 1273K in the initial stage. However, the methane conversion decreases with reaction time due to deactivation of the lignite char by carbon deposition on surface of the char. The results also show that higher initial methane conversion is achieved at higher temperature. Furthermore, the higher the methane concentration, the lower the methane conversion and the faster the deactivation of the char occurs. During the reaction the carbon deposits on the surface of the char.The spent char shows a lower surface area, total pore and micropore volumes, and larger pore diameters than those of the fresh char. This observation seems to suggest that the carbon deposition takes place in the pores, especially in the micropores of the char, leading to blockage of the pores for continuing catalytic cracking of methane.