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Article

Activated Carbons for Syngas Desulfurization: Evaluating Approaches for Enhancing Low-Temperature H2S Oxidation Rate

VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 Espoo, Finland
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Academic Editor: Martín Ramírez
ChemEngineering 2021, 5(2), 23; https://doi.org/10.3390/chemengineering5020023
Received: 17 March 2021 / Revised: 6 May 2021 / Accepted: 6 May 2021 / Published: 11 May 2021
Its relatively low cost and high surface area makes activated carbon an ideal adsorbent candidate for H2S removal. However, physical adsorption of H2S is not very effective; therefore, methods to facilitate reactive H2S oxidation on carbons are of interest. The performance of H2S removal of non-impregnated, impregnated, and doped activated carbon in low-temperature syngas was evaluated in fixed-bed breakthrough tests. The importance of oxygen content and relative humidity was established for reactive H2S removal. Impregnates especially improved the adsorption rate compared to non-impregnated carbons. Non-impregnated carbons could however retain a high capture capacity with sufficient contact time. In a relative performance test, the best performance was achieved by doped activated carbon, 320 mg g−1. Ammonia in syngas was found to significantly improve the adsorption rate of non-impregnated activated carbon. A small quantity of ammonia was consumed by the carbon bed, suggesting that ammonia is a reactant. Finally, to validate ammonia-enhanced desulfurization, bench-scale experiments were performed in biomass-based gasification syngas. The results show that when the ammonia concentration in syngas was in the tens of ppm range, 40–160 ppm H2S oxidation proceeded rapidly. Ammonia-enhanced oxidation allows utilization of cheaper non-impregnated activated carbons by in situ improvement of the adsorption kinetics. Ammonia enhancement is therefore established as a viable method for achieving high-capacity H2S removal with unmodified activated carbons. View Full-Text
Keywords: syngas desulfurization; activated carbon; hydrogen sulfide; H2S oxidation; ammonia syngas desulfurization; activated carbon; hydrogen sulfide; H2S oxidation; ammonia
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MDPI and ACS Style

Frilund, C.; Hiltunen, I.; Simell, P. Activated Carbons for Syngas Desulfurization: Evaluating Approaches for Enhancing Low-Temperature H2S Oxidation Rate. ChemEngineering 2021, 5, 23. https://doi.org/10.3390/chemengineering5020023

AMA Style

Frilund C, Hiltunen I, Simell P. Activated Carbons for Syngas Desulfurization: Evaluating Approaches for Enhancing Low-Temperature H2S Oxidation Rate. ChemEngineering. 2021; 5(2):23. https://doi.org/10.3390/chemengineering5020023

Chicago/Turabian Style

Frilund, Christian, Ilkka Hiltunen, and Pekka Simell. 2021. "Activated Carbons for Syngas Desulfurization: Evaluating Approaches for Enhancing Low-Temperature H2S Oxidation Rate" ChemEngineering 5, no. 2: 23. https://doi.org/10.3390/chemengineering5020023

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