Enhancing Kinetics of Carbonyl Sulfide Hydrolysis Using Pt-Supported Al₂O₃ Catalysts: First-Principles-Informed Energetic Span Analysis

Abstract

Catalytic hydrolysis is considered an effective strategy for treating carbonyl sulfide (COS)�a toxic sulfurcontaining gas that causes problems to the environment and petrochemical industries. Al 2 O 3 -based materials are commonly used as catalysts for COS hydrolysis owing to their stability and cost effectiveness. However, they still suffer from sulfur poisoning leading to partial COS conversion after long time use. To improve their catalytic performances, herein, we computationally designed and studied the catalytic activity of the Pt-supported Al 2 O 3 catalysts by means of density functional calculations. We mechanistically explored the COS hydrolysis on both bare and Pt-decorated surfaces to reveal the role of Pt catalysts in the reaction kinetics. We find that bare Al 2 O 3 suffers from difficult C− S bond breaking as its barrier is relatively high. Pt facilitates C−S bond breaking where its barrier is reduced by more than half (1.34 to 0.60 eV). However, the Pt−Al 2 O 3 catalyst could encounter sulfur poisoning as the sulfur-containing intermediates are rather stable. Such issues could be remedied by increasing the operating temperature to destabilize the intermediates and promote product desorption. The energetic span models reveal that the important states of bare and Pt−Al 2 O 3 are indeed C−S bond breaking and product desorption corresponding to an energy span of 2.72 and 1.67 eV at 773 K, respectively�suggesting that Pt dramatically enhances the catalytic activity of Al 2 O 3 -based catalysts toward COS hydrolysis. The suggested operating temperatures are above 673 K to avoid sulfur poisoning. Our findings will be useful for the development of more efficient Al 2 O 3 -based catalysts for treating COS.

Catalytic hydrolysis of carbonyl sulfide in blast furnace gas over Sm-Ce-Ox@ZrO2 catalyst

“…13–16 The H 2 S produced by hydrolysis is easily oxidised to monosulfur or further oxidised to sulphate, which is deposited on the surface of the catalyst, thus clogging up the holes of the catalyst. 17,18 γ-Al 2 O 3 is strongly acidic, which reduces the surface alkalinity of aluminium-based catalysts, making the catalysts inadequate in low-temperature hydrolysis performance and stability. 19 In contrast, TiO 2 has stronger resistance to sulfate, and TiO 2 itself has better catalytic hydrolysis ability for COS, but the relatively small specific surface area of TiO 2 will limit its application to some extent.…”