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°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 H₂/CO ratio in the product gas was less than 1 (~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.