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<p>Natural gas, an essential energy source, often contains undesirable acidic components such as hydrogen sulfide (H<sub>2</sub>S) and carbon dioxide (CO<sub>2</sub>), which must be removed to prevent corrosion, environmental pollution, and efficiency loss. During the dehydration of acid gases, the formation of carbonyl sulfide (COS) and elemental sulfur poses significant operational challenges, particularly in temperature swing adsorption (TSA) units using molecular sieves. Although COS is initially non-corrosive, it can hydrolyze to form H<sub>2</sub>S and CO<sub>2</sub>, exacerbating corrosion and reducing process reliability. In this study, molecular simulations using the RASPA (Version 2) code were employed to investigate the adsorption behavior of H<sub>2</sub>O, H<sub>2</sub>S, and CO<sub>2</sub>, and to explore the reaction pathways leading to COS and elemental sulfur formation in Na-LTA4A zeolite. The Langmuir–Freundlich model was applied to describe the adsorption isotherms, while the Aspen Adsorption (Version 12.1) software was used to simulate the TSA process under various operational conditions. Simulation results reveal that Na-LTA4A enhances H<sub>2</sub>S conversion to COS up to 81% at 523&#xa0;K, and COS decomposition to elemental sulfur occurs effectively above 450&#xa0;K. The effects of regeneration gas temperature, flow rate, H<sub>2</sub>S concentration, and gas type were systematically analyzed. Among these, the composition of the regeneration gas was found to be the most effective parameter in controlling sulfur formation. Substituting dry acid gas with pure CO<sub>2</sub>, CH<sub>4</sub>, or N<sub>2</sub> significantly reduces elemental sulfur production. This combined molecular–process modeling approach provides a cost-effective and safe alternative to experimental studies, offering molecular-level insight and practical guidelines for optimizing dehydration processes to minimize sulfur formation and improve unit performance.</p>

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Mitigating elemental sulfur in dehydration unit using Na-LTA4A zeolite: Molecular simulation and process optimization

  • 期刊论文

  • 发表日期：

    2026年5月18日

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  • Sara Abbasi,
  • Mohammad Ahmadi,
  • Mohammad Reza Khosravi-Nikou,
  • Ahmad Shariati

摘要

Natural gas, an essential energy source, often contains undesirable acidic components such as hydrogen sulfide (H2S) and carbon dioxide (CO2), which must be removed to prevent corrosion, environmental pollution, and efficiency loss. During the dehydration of acid gases, the formation of carbonyl sulfide (COS) and elemental sulfur poses significant operational challenges, particularly in temperature swing adsorption (TSA) units using molecular sieves. Although COS is initially non-corrosive, it can hydrolyze to form H2S and CO2, exacerbating corrosion and reducing process reliability. In this study, molecular simulations using the RASPA (Version 2) code were employed to investigate the adsorption behavior of H2O, H2S, and CO2, and to explore the reaction pathways leading to COS and elemental sulfur formation in Na-LTA4A zeolite. The Langmuir–Freundlich model was applied to describe the adsorption isotherms, while the Aspen Adsorption (Version 12.1) software was used to simulate the TSA process under various operational conditions. Simulation results reveal that Na-LTA4A enhances H2S conversion to COS up to 81% at 523 K, and COS decomposition to elemental sulfur occurs effectively above 450 K. The effects of regeneration gas temperature, flow rate, H2S concentration, and gas type were systematically analyzed. Among these, the composition of the regeneration gas was found to be the most effective parameter in controlling sulfur formation. Substituting dry acid gas with pure CO2, CH4, or N2 significantly reduces elemental sulfur production. This combined molecular–process modeling approach provides a cost-effective and safe alternative to experimental studies, offering molecular-level insight and practical guidelines for optimizing dehydration processes to minimize sulfur formation and improve unit performance.