High-Pressure CH₄ Reforming for Tunable Syngas Generation with CO₂ Utilization via Fe–Al-Based Composite Metal Oxides

Dry reforming of methane (DRM) at high pressure offers a promising avenue for CO2 utilization and efficient integration with downstream syngas-based processes. However, catalyst deactivation due to the accumulation of carbon over time poses a significant hindrance to its deployment. This study attempts at overcoming this hindrance through enhanced dry reforming (EDR), which incorporates excess CO2 relative to CH4, and mixed reforming of methane (MRM), which uses a mixture of H2O and CO2 as oxidizing gases. Both approaches employ Fe–Al-based composite metal oxides to enable sustainable high-pressure syngas production without carbon deposition, with MRM offering a tunable H2:CO ratio for flexibility of downstream applications. Through a comprehensive thermodynamic analysis, an optimal CO2:CH4 feed ratio of 1.5 is identified for EDR for maximum CO2 utilization while avoiding the carbon formation zone. These conditions are found to be applicable up to 25 bar, with experimental tests showcasing stable EDR performance for 850 h at ambient pressure, 150 h at 10 bar, and at a pressure as high as 25 bar (10 h). Furthermore, syngas composition suitable for liquid fuel production through Fischer–Tropsch synthesis is explored via MRM using H2O as an additional oxidant. This approach led to successful stable syngas generation with a tunable H2:CO ratio of up to ∼1.8 at high pressure.