Desulfurization kinetics of ZnO sorbent loaded on semi-coke support for hot coal gas

Zn-based sorbent （Z20SC） prepared through semi-coke support in 20 wt% zinc nitrate solution by high-pressure impregnation presents an excellent desulfurization capacity in hot coal gas,in which H2 S can not be nearly detected in the outlet gas before 20 h breakthrough time.The effects of the main operational conditions and the particle size of Z20SC sorbent on its desulfurization performances sorbent were investigated in a fixed-bed reactor and the desulfurization kinetics of Z20SC sorbent removing H2 S from hot coal gas was calculated based on experimental data.Results showed that the conversion of Z20SC sorbent desulfurization reaction increased with the decrease of the particle size of the sorbent and the increases of gas volumetric flow rate,reaction temperature and H 2 S content in inlet gas.Z20SC sorbent obtained from hydrothermal synthesis by high-pressure impregnation possessed much larger surface area and pore volume than semi-coke support,and they were significantly reduced after the desulfurization reaction.The equivalent grain model was reasonably used to analyze experimental data,in which k s=4.382×10-3 exp（-8.270×103/RgT） and Dep=1.262×10-4exp（1.522×104/RgT）.It suggests that the desulfurization reaction of the Z20SC sorbent is mainly controlled by the chemical reaction in the initial stage and later by the diffusion through the reacted sorbent layer.

Desulfurization performance of iron-manganese-based sorbent for hot coal gas

A series of iron-manganese-based sorbents were prepared by co-precipitation and physical mixing method,and used for H_(2)S removal from hot coal gas.The sulfidation tests were carried out in a fixed-bed reactor with space velocity of 2000 h^(-1)(STP).The results show that the suitable addition of manganese oxide in iron-based sorbent can decrease H_(2)S and COS concentration in exit before breakthrough due to its simultaneous reaction capability with H_(2)S and COS.Fe3O4 and MnO are the initial active components in iron-manganese-based sorbent,and FeO and Fe are active components formed by reduction during sulfidation.The crystal phases of iron affect obviously their desulfurization capacity.The reducibility of sorbent changes with the content of MnO in sorbent.S7F3M and S3F7M have bigger sulfur capacities(32.68 and 32.30 gS/100 g total active component),while S5F5M has smaller sulfur capacity(21.92 gS/100 g total active component).S7F3M sorbent has stable sulfidation performance in three sulfidation-regeneration cycles and no apparent structure degradation.The sulfidation performance of ironmanganese-based sorbent is also related with its specific surface area and pore volume.

A review on research and development of iron-based sorbents for removal of hydrogen sulfide from hot coal gases

In poly-generation and integrated gasificationcombined cycle(IGCC)systems for clean energy conversion,it is essential to remove impurities such as sulfur species from hot coal gases prior to entering the subsequent units.This paper provides a comprehensive review on previous studies on high temperature removal of hydrogen sulfide from high temperature coal gases using iron-based sorbents.A two-step desulphurization process for hot coal gas cleanup is highlighted,which is integrated with direct production of elemental sulfur during regeneration of ironbased sorbents in the primary desulphurization step.Different kinetic modeling approaches for sulfidation and regeneration were compared.Limited research on activated carbon supported sorbents was also briefly summarized.