Study On The Desulfurization And Regeneration Performance Of Iron-based Desulfurizer At Room Temperature

CO₂ recovery and re-sourcing can effectively reduce large amounts of CO₂ emissions,alleviate environmental pollution problems such as the greenhouse effect,and achieve carbon neutrality,which is very significance to human survival and development.CO₂ produced in industrial processes such as natural gas combustion and petroleum refining can be used as a high-quality raw material gas for food-grade CO₂ production after capture,but its application is limited by the presence of impurity gases such as H₂S,a corrosive gas that not only endangers human health but also corrodes production equipment,poisons catalysts and industrial products.Many industrial processes have strict requirements for the concentration of H₂S in the raw gas,and the industry standard for food grade CO₂ requires that the concentration of hydrogen sulfide be less than 0.1 ppm.In order to achieve the removal of H₂S from CO₂ gas sources,various desulfurization agents are applied to industrial production processes,among which most of the desulfurization agents used for low-temperature desulfurization have low sulfur capacity,low desulfurization accuracy and difficult to regenerate,so it is important to develop high-efficiency desulfurization agents with fine removal of H₂S at low temperature conditions.In this paper,hydrated ferric oxide（HFO）is the main research object,and the desulfurization agent is studied in terms of preparation method,addition of carrier and regeneration performance,etc.The results show that HFO can achieve the fine desulfurization of H₂S in CO₂ at low temperature,and the desulfurization accuracy can be less than 0.1 ppm.A series of HFO composite metal oxide desulfurizers were prepared by adding porous materials,among which,the low-temperature desulfurization performance of HFO samples with MWCNTs was significantly improved.The desulfurization performance of the composite desulfurization agent showed a trend of increasing and then decreasing with the addition of MWCNTs,reaching a maximum of 144.2 mg g^-1 at the addition level of 20 wt.%,which was1.73 times higher than that of the pure HFO sample.The characterization and VASP calculations showed that the addition of MWCNTs changed the physicochemical properties of the HFO samples,such as the increase in the degree of surface defects and dispersion,and the formation of Fe-O-C chemical bond between HFO and MWCNTs,which improved the electron transfer rate during the desulfurization reaction.The highly dispersed HFO nanoparticles immobilized on the surface of MWCNTs expose more surface active sites,resulting in a significant enhancement of the desulfurization performance.The regeneration method,regeneration atmosphere and regeneration temperature all affect the regeneration performance of HFO desulfurizer,and the penetration adsorption amount of sulfated HFO regenerated with simulated air with 2%water content at 40 ^oC reached 15.18 mg g^-1,which is 37.5%of that of the unreacted HFO.The characterization results showed that the regenerated samples had a large amount of S singlet attached to the surface and pore channels of HFO,resulting in a significant decrease in the specific surface area and pore volume of HFO,which hindered the further reaction between H₂S and active components,thus causing a decrease in the desulfurization performance.the addition of MWCNTs failed to significantly improve the regeneration rate of HFO,and the regeneration of simulated air with 2%water content at 40 ^oC resulted in a significant decrease in the Fe C-0.2 sample with H₂S penetration adsorption was 22.8 mg g^-1,which was 37.6%of the fresh sample.