Rational design of poisoning-resistant catalyst based on γ-Al2O3 for hydrolysis of carbonyl sulfide

Abstract

Catalytic hydrolysis of carbonyl sulfide (COS) is an efficient way of desulfurization for industrial flue gas, while the frequently used Al2O3-based catalysts always suffer from sulfur poisoning leading to poor stability, especially in the presence of O2. With this regard, an analysis of the reaction pathway has been conducted, and the tri-coordinated Al in γ-Al2O3 is identified as the responsible site for poisoning, on which produced H2S is over-oxidized resulting in active sites covering. Density functional theory (DFT) has been adopted for dopant screening to eliminate tri-coordinated Al on γ-Al2O3, inhibit H2S over-oxidation, and prevent sulfur poisoning. Results show La, Fe, Ni, and Cu all can eliminate tri-coordinated Al, while only La-doped γ-Al2O3 exhibits inhibition to H2S oxidation, thus, improving activity and stability for γ-Al2O3. Experiments show COS conversion of 99 % over 30 h can be attained in the presence of O2, which agrees well with the DFT calculation.