Preparation And Desulfurization Performance Of La(Sm)MeO_x/SBA-15 For Hot Coal Gas

Clean and efficient utilization of coal is becoming more and more important as the requirement of environmental protection. The coal gas from the coal gasification processes contains sulfur compounds, which mostly existed in the form of H₂S and must be removed prior to utilization to avoid severe corrosion of the system equipments and infringement of emissions legislation. Several techniques are available for the removal of H₂S, including wet absorption. However, these techniques have a common disadvantage, i.e. the hot coal gas must be cooled to ambient temperature and then heated once again to a desired temperature. Hot coal gas desulfurization (HGD) can improve the thermal efficiencies due to the save of potential heat. Metal oxides have been used as regenerable desulfurizers for the direct removal of H₂S at high temperature. Metal oxides have high sulfur sorption capacity but they suffered from several problems, such as sintering, low duration and mechanical disintegrations that affect their performance and life time adversely. Pure metal oxides or their admixtures loaded on inert materials have been used to overcome these problems.La(Sm)MeOx/SBA-15 (Me = Zn, Co and Fe) desulfurizers were prepared and its desulfurization performance for hot coal gas was investigated. La(Sm)FeO₃/SBA-15 exhibited better desulfurization performance than La(Sm)2CoO4/SBA-15 and La(Sm)₂ZnO₄/SBA-15. The characterization results of BET, XPS and XRD suggested that the structure of support SBA-15 almost remained intact before and after desulfurizers were used. The metal oxides supported on SBA-15 can effectively suppress mechanical disintegration and improve the stability of desulfurizer. The results of successive sulfidation and regneration cycles revealed that La(Sm)FeO₃/SBA-15 presented high performance and stability for the removal of H₂S in hot coal gas.