Comparison of different types of tannin extracts and tannic acid for coal syngas desulfurization

In this study,an industrial process using tannin extracts for H2 S removal from semi-water gas and converter gas is investigated. The compositions of valonia,black wattle and industrial tannin extracts are analyzed. The kinetics of sulfide oxidation is also performed. The results show that the content of tannic acid is the major difference in the composition of these three tannin extracts. The hot alkaline pretreatment significantly enhances the sulfide removal efficiency for the three tannin extracts,but leads to almost no change for tannic acid. The FT-IR shows that the νO—HandνCOOHfunction groups for the tannin extracts are generated after the pretreatment whereas these groups are not observed for pretreated tannic acid. The ratio of tannin extract to V2O5 does not affect the rates and side-reactions of sulfide oxidation.