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.