Effective removal of odorants in gaseous fuel for the hydrogen station using hydrodesulfurization and adsorption

The removal efficiency of dimethyl sulfide (DMS), tert-butylmercapatan (TBM), and tetrahydo thiophene (THT) was investigated for applying to hydrogen station. The sorbents such as Cu/Al₂O₃, ZnO/Al₂O₃, Cu/ZnO, and Cu/ZnO/Al₂O₃ were prepared by the coprecipitation method and characterized by XRD, surface area, and pore size distribution measurements. Among the various sorbents employed for the removal sulfur compounds, the Cu/ZnO/Al₂O₃ exhibits superior activity compared to the conventional ZnO sorbent (G-72D) as well as the others. The order of sorption capacity for the removal sulfur compounds after hydrodesulfurization (HDS) was found to be Cu/ZnO/Al₂O₃ > Cu/ZnO > Cu/ Al₂O₃ > ZnO/Al₂O₃ > G-72D. The BET surface area and pore volume of Cu-ZnO based sorbents were found to be higher than other sorbents, and it suggests that ZnO effectively enhanced the dispersion of Cu in Cu/ZnO/ Al₂O₃ sorbent. In the modified HDS system combining with adsorption of sulfur compounds by Cu/ZnO/Al₂O₃, the sulfur compounds such as DMS, EMS, and TBM in isobutane were removed more effectively with higher sulfur capacity than the conventional desulfurization system of HDS with ZnO trap. Moreover, the modified system would provide safer operation possibility of hydrogen station, exhibiting much less sulfur passing out at the temperatures below 250 °C.