Characterization of catalytic partial oxidation of methane with carbon dioxide utilization and excess enthalpy recovery

Highlights: • Catalytic partial oxidation of methane using a rhodium-based catalyst is studied. • CO₂ is added in the feed gas and excess enthalpy recovery is performed. • Atleast 18.2% and upto 77.0% of CO₂ in the feed gas is converted to CO. • Energy efficiency of the reaction system is between 83.5% and 89.9%. • CPOM performed at O₂/CH₄ = 0.6 gives better CO₂ consumption and energy efficiency. - Abstract: The characteristics of catalytic partial oxidation of methane (CPOM) under CO₂ addition and excess enthalpy recovery are investigated where a rhodium-based catalyst is employed. The influences of O₂/CH₄ and CO₂/O₂ molar ratios, in the ranges of 0.4–0.7 and 0–2, respectively, on CPOM performance are emphasized. The energy efficiency of the Swiss-roll reactor is also studied. The results reveal that the O₂/CH₄ ratio plays a crucial role in methane conversion, whereas it is insensitive to the CO₂/O₂ ratio. The H₂ contributed by steam reforming is pronounced at higher O₂/CH₄ ratios; on the other hand, H₂ produced from dry reforming is significant at lower O₂/CH₄ ratios and high CO₂/O₂ ratios. The H₂/CO ratio in the product gas is between 1 and 2, and the values depends on the O₂/CH₄ and CO₂/O₂ ratios. Increasing CO₂/O₂ ratio substantially increases CO₂ consumption, but leads to a decrease in CO₂ conversion. Within the investigated ranges of O₂/CH₄ and CO₂/O₂ ratios, at least 18.2% and up to 77.0% of CO₂ in the feed gas is converted to CO. The energy efficiency of the reaction system with considering CH₄ conversion is between 83.5% and 89.9%. Overall, CPOM performed at O₂/CH₄ = 0.6 is recommended in that it provides higher CH₄ conversion, syngas production, CO₂ consumption, and system energy efficiency.