Mo-Doped FeS Mediated H₂ Production from H₂S via an In Situ Cyclic Sulfur Looping Scheme

Abstract

Decomposition of H 2 S into sulfur and clean fuel H 2 is an attractive process and requires a design concept with a maximum H 2 S conversion and a minimal energy consumption. Herein, we demonstrate a sulfur looping scheme in a one-reactor system using a low-cost and environmentally safe iron-based sulfur carrier. H 2 S decomposition is split into cyclic sulfidation and regeneration of sulfur carriers, which overcomes the inherent thermodynamic constraint, allowing in situ H 2 generation. We experimentally obtained 24% higher sulfur uptake in 2% Mo-doped iron-based sulfur carriers compared with undoped sulfur carriers. The reaction mechanisms unveiled by the density functional theory indicate that surface hydrogen diffusion is the rate-determining step for sulfidation of the sulfur carrier. Compared with the undoped sulfur carrier, Mo dopant facilitates the surface hydrogen diffusion, thus promoting the overall H 2 S conversion. This work demonstrates a novel strategy for high-yielding H 2 S removal through low-percentage dopant modification sulfur carrier and provides new insights for an effective dopant screening strategy aiding the future carrier design.

Review of Theoretical and Computational Studies of Bulk and Single Atom Catalysts for H2S Catalytic Conversion

“…[184,185] Single transition atoms anchoring at cation or anion defects of metal compounds can be as nice catalyst for the removal of H 2 S under various reaction conditions. [34,169,186,187] Titanium dioxide (TiO 2 ) is excellent catalyst support for fixed single atoms for the removal of H 2 S. Using DFT + U with PBE calculations, Zheng et al [34] found that the doped Fe atom can slightly promote adsorption and dissociation of H 2 S on TiO 2 (101) surfaces. The doped Fe atom can change the electron structure of the TiO 2 (101) surface and move the position of Fermi Level to right comparing with DOS of the pure TiO 2 (101) surface (Figure 7a).…”

“…Combining with experiment and theory, Jangam et al [187] studied the dissociation of H 2 S into S and H 2 on pure and Modoped FeS catalysts. Experimentally they found that 24 % higher sulfur uptake was obtained in the 2 % Mo-doped FeS catalyst compared with pure FeS catalyst.…”

“…It has been widely reported that metal compounds can be used in numerous fields because of their unique structure properties with abundant cation or anion defects, which provide numerous sites for anchoring the isolated metal atoms [184,185] . Single transition atoms anchoring at cation or anion defects of metal compounds can be as nice catalyst for the removal of H 2 S under various reaction conditions [34,169,186,187] …”

Catalytic Conversion of H2S to H2: Challenges and Catalyst Limitations

“…Many attempts were made in the literature to achieve this objective. Methods include partial oxidation, reformation, , thermal (non-catalytic), thermal (catalytic), photochemical, plasmolysis, chemical cycle, , and electrolysis . Despite these attempts, none of methods have achieved a commercial application.…”

Catalytic conversion of H2S to H2: Challenges and Catalyst Limitations

“…Many attempts were made in the literature to achieve this objective. Methods include partial oxidation [7], reformation [8,9], thermal (non-catalytic) [10], thermal (catalytic) [11], photochemical [12], plasmolysis [13], chemical cycle [14,15] and electrolysis [16]. Despite these attempts, none of methods have achieved a commercial application.…”