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

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 HO 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 HO decreased the SRC, as expected, the highest reduction in the capacity occurred in the CO-HS 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 HO 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 H and HO. This indicates that it is critical to control the residence time of syngas and temperature to reduce COS formation during ZnO adsorption.