Removal of Hydrogen Sulfur from Coal-Derived Gas by Iron Oxides in Various Oxisols

Abstract

Five oxisols sampled from Taiwan were applied to remove sulfur species from coal-derived gas. Sorption of H2_S was conducted by loading oxisols into a fixed–bed reactor under a temperature of 500°C. All of the oxisols had some sorption ability under these experimental conditions. The sulfur sorption capacities of the five oxisols decreased in the following trend: Tungwei > Shouka > Tamshui > Loupi > Pingchen. The difference of sulfur capacity for the tested oxisols was attributed to the dithionite–citrate–bicarbonate (DCB) extractable iron. For all oxisols, the sulfur sorption capacity derived from breakthrough time experiments is in line with those measured by elemental analysis. Sulfur recovery of the five oxisols ranges from 93.4 to 103.1%. Sulfur sorption capacity of oxisols attributed to DCB extractable iron oxides is close to that obtained by calculation (breakthrough time) and elemental analysis. It is suggested that the major mechanism of sulfur uptake by oxisol is attributed to the reaction between DCB extractable iron oxides and H₂S. Higher CO concentration has a positive effect on the sorption of H₂S, whereas H₂ appears to have a negative effect. The water-shift reaction can explain this result.