Residual Hydrogen Sulfide in Recovered Liquid Sulfur: A Computational Investigation
Year: 2025
Type: article
Abstract: The nature, structure, stability and reaction of sulfur clusters (S n ) with H 2 S leading to the formation of hydrogen polysulfanes (HS n +1 H) in a critical equilibrium in the modified thermal Claus process are investigated using density functional theory (DFT) and coupled cluster (CC) theory. The computations reveal that S n ( n ≤ 4) possess open chain ground state structures while S 5 and S 8 have cyclic ground state structures and that as n increases for open chain structures, a switch in stability of spin states occurs at S 3 and S 5 . Triplet state open chains of S 5 and S 8 are computed to be more stable than their singlet state analogues, even though their global minimum cyclic structures are singlet state species. This provides a plausible explanation for the paramagnetic behavior of liquid sulfur. Furthermore, the results suggest that branched and unbranched HS n +1 H are only formed on the singlet surface of the S n + H 2 S reaction where S n are open chain structures. The unbranched HS n +1 H are formed in exergonic processes while branched HS n +1 H are either formed in exergonic or endergonic processes depending on n . The reaction product on the triplet surface in all cases may best be described as weakly attracted doublet species that are always formed in endergonic processes. This suggests that the exergonicity of the reverse of the triplet surfaces for these reactions may be responsible for the residual H 2 S found in recovered liquid sulfur.
Authors: Msugh Targema, John F. C. Turner, Hazel Cox
Institution: University of Sussex
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funder: Tertiary Education Trust Fund
Awards: G2004282612, G6608026425
OpenAlex ID: W4415816320