Cost-effective lanthanum-promoted iron catalyst on coal gangue-derived mesoporous γ-Al2O3 for SO2 catalytic reduction.

A highly active and stable SO2 reduction catalyst, 3%La-15%Fe/γ-Al2O3, was successfully synthesized using γ-Al2O3 derived from coal gangue. The structural properties of the synthesized catalyst were analyzed using XPS, SEM, TEM, EDS, BET, XRD, and H2-TPR. Characterization studies revealed a high BET specific surface area of 288.55 m2/g for the coal gangue-derived mesoporous γ-Al2O3. Furthermore, lanthanum doping inhibited iron crystallite growth, enhancing dispersion on the support and contributing to superior catalytic performance. Under optimized conditions (380 °C, 6000 h-1 GHSV, and a CO/SO2 ratio of 2), the catalyst achieved 98.92 ± 1.3% SO2 conversion and 99.43 ± 0.7% selectivity to elemental sulfur. This high performance remained stable for over 50 h, demonstrating the catalyst's potential for industrial application. The utilization of coal gangue-derived γ-Al2O3 offers both economic and environmental benefits by providing a cost-effective support material and addressing coal gangue disposal challenges. This work presents a promising strategy for sustainable SO2 abatement and resource utilization.