Bimetallic Metal-Organic Frameworks MIL-53(Al-Fe) as Efficient Catalysts for HS Selective Oxidation.

Catalytic oxidation of HS is a crucial green pathway that can fully convert HS into value-added elemental S for commercial use. However, achieving high catalytic stability and S selectivity by traditional-metal-based catalysts still remain a major challenge. Herein, a facile one-step solvothermal strategy is designed for the fabrication of bimetallic MIL-53(Al-Fe) catalysts. The as-synthesized MIL-53(1Al-5Fe) possesses ample coordinatively unsaturated metal sites, which served as efficient catalytic sites for the selective oxidation of HS. As a result, the representative MIL-53(1Al-5Fe) achieves a S yield of nearly 100% at 100-160 °C with almost no obvious decrease of catalytic stability in the run of 30 h. Under the defined reaction conditions, the bimetallic metal-organic frameworks are obviously superior to MIL-53(Al) (49.3%) and MIL-53(Fe) (70.5%) in S yield. This study suggests that the introduction of elemental Al into MIL-53(Al-Fe) could effectively modulate the electronic properties and spatial configuration of the catalysts, further conducing the adsorption and activation of HS and thus accelerating the dissociation of HS into a key intermediate S* and improving their catalytic performance.