The effect of the presence of water on sulfur removal capacity during H₂S removal from syngas using ZnO adsorbent

ABSTRACT

Compared to extensive studies on affecting parameters in sulfur removal with ZnO adsorbents from coal gasification syngas, similar studies conducted for biomass gasification syngas (BGS) are quite rare. Thus, considering the BGSs with high water content, this study was performed to investigate the effect of H₂O presence in syngas on sulfur removal capacity (SRC) of ZnO adsorbents. Initially, the effect of gas composition and temperature on SRC in binary gas mixture was investigated. While H₂O decreased the SRC, as expected, the highest reduction in the capacity occurred in the CO–H₂S gas mixture due to observed COS formation. Second, the SRCs and resulting COS formation were compared for synthetic syngas mixtures having different water contents and for different amounts of adsorbents. Finally, the separate and combined effects of temperature and H₂O on SRC and COS formation in synthetic syngas were investigated by comparing SRCs of typical syngas under wet and dry conditions. The results showed that increasing the amount of adsorbent and temperature results in higher SRC due to a reduction in COS formation through the reactions of COS with H₂ and H₂O. This indicates that it is critical to control the residence time of syngas and temperature to reduce COS formation during ZnO adsorption.

GRAPHICAL ABSTRACT

KEYWORDS:

• Biomass gasification
• desulfurization
• H₂S
• ZnO
• COS
• adsorption

Acknowledgements

The work was supported by the Austrian Research Promotion Agency FFG [grant numbers 869036 and 8721489] and the Styrian Business Promotion Agency SFG [grant number 1.000.058.397]. The first author acknowledges the Scientific and Technological Research Council of Turkey (TUBITAK) for the scholarship provided within the 2214-A PhD research fellowship program.

Data availability statement

The data used to support the findings of this study are available from the corresponding author upon request.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the Austrian Research Promotion Agency FFG [grant numbers 869036 and 8721489], the Styrian Business Promotion Agency SFG [grant number 1.000.058.397], and Scientific and Technological Research Council of Turkey (TUBITAK) 2214-A PhD research fellowship program.