Bimetallic Metal–Organic Frameworks MIL-53(<i>x</i>Al–<i>y</i>Fe) as Efficient Catalysts for H<sub>2</sub>S Selective Oxidation
Xiaoxiao Zheng, Lijuan Shen, Fengcai Lin, Yanlian Xu, Qi Lin, Lilong Jiang
Abstract
Catalytic oxidation of H2S is a crucial green pathway that can fully convert H2S 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(xAl–yFe) 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 H2S. 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(xAl–yFe) could effectively modulate the electronic properties and spatial configuration of the catalysts, further conducing the adsorption and activation of H2S and thus accelerating the dissociation of H2S into a key intermediate S* and improving their catalytic performance.