Stable Syngas Production by Concurrent Methane Decomposition and Carbon Dioxide Gasification with Activated Carbon

CH4 decomposition and CO2 gasification with activated carbon (AC) were concurrently conducted to stably produce syngas at 800-950 degrees C. With a CH4/CO2 feed ratio of 1 or less, both reaction rates remained nearly constant with time, while the CH4 decomposition rate decreased significantly at higher ratios. As the CH4/CO2 ratio increased from 0.3 to 3, the weight loss of AC decreased from 28% to less than 1% under the reaction conditions investigated. Even though the CH4 decomposition rate was close to or greater than the CO2 gasification rate, the H-2/CO ratio in the product gas was less than 1 (similar to 0.9), which is consistent with the thermodynamic prediction. The reaction orders with respect to CH4 and CO2 for the concurrent reactions were 0.52 and 0.58, respectively. The activation energies for CH4 decomposition and CO2 gasification were 108.3 and 75.1 kJ/mol, respectively, which suggest that the surface carbon atoms exposed after CO liberation by CO2 gasification are more active for both reactions than before CO liberation. Based on these results, stable operating conditions were recommended.