Rational Design and Synergistic Effects of K-Fe-Ca Ternary Catalyst for Enhanced Coal Gasification Efficiency in H2 and CH4 Production

Supercritical water gasification (SCWG) is an essential technology for achieving low-carbon and high-value utilization of coal; however, traditional gasification methods face challenges such as high reaction temperatures, low product selectivity, and a lack of rational catalyst design. In this study, we first quantified inherent metallic elements in coal and identified that K, Fe, and Ca show statistically significant positive correlations with H2 and CH4 yields. Based on this feedstock-adapted guideline, a novel K–Fe–Ca/Al ternary catalyst was rationally designed and synthesized via a stepwise impregnation method. Characterizations confirmed the successful loading and uniform dispersion of active components on the γ-Al2O3 support. The ternary catalyst exhibited remarkable synergistic effects and significantly boosted H2 and CH4 yields, far superior to those of physical mixtures. Mechanistic analysis revealed the integrated functions of K for gasification promotion, Fe for reversible redox cycles, and Ca for in-situ CO2 capture and anti-deactivation performance. This work provides a new paradigm for data-driven catalyst design in coal SCWG and offers a theoretical foundation for efficient and clean coal conversion. This rational, data-driven research design ensures the reliability and scientific rigor of the catalyst development for coal SCWG.