Performance Of Molecular Sieve Adsorbent For Removing COS And H₂S From Blast Furnace Gas And Optimization Of Operating Parameters

Blast furnace gas is a combustible gas produced by the blast furnace ironmaking process,and it can be utilizated as an raw materials.However,sulfur-containing compounds such as COS and H₂S contained in blast furnace gas will be converted into SOx after the gas is burned,causing environmental pollution.Therefore,it is necessary to remove COS and H₂S from blast furnace gas.Among the many gas desulfurization methods,the molecular sieve adsorption method has the advantages of good regeneration cycle performance and easy operation,which is favored by the industry and the most promising desulfurization method.At present,the molecular sieve desulfurization adsorbents used in industrial demonstration devices are mainly FAU and MFI molecular sieves.Taking them as the research sample,the desulfurization performance of the adsorbent is investigated,and the optimization of operating parameters can be used for the screening of molecular sieve desulfurization adsorbents.It provides data support for industrial applications and has practical and research value.Based on this,four FAU type(FAU-1,FAU-2,FAU-3 and FAU-4)molecular sieve adsorbents and four MFI types(MFI-1,MFI-2,MFI-3 and MFI-4)molecular sieve adsorbents were selected in this article.First,the fixed bed desulfurization evaluation device was used to investigate its adsorption performance for COS and H₂S in blast furnace gas,and molecular sieves with better desulfurization performance were screened out.Secondly,with the optimized FAU molecular sieve adsorbent as the research sample,the influence of CO₂ and H₂O in blast furnace gas on the removal of COS and H₂S was discussed.Finally,taking the adsorbent with the best desulfurization performance as the research object,the influence of the working conditions(temperature and gaseous hourly space velocity)of blast furnace gas on the removal of COS and H₂S by the molecular sieve adsorbent was explored.The main findings are as follows:(1)ICP,nitrogen adsorption,FTIR,CO₂-TPD and static water absorption and other characterization methods were used to test and analyze the composition,structure,surface functional groups,type and content of basic sites,and water absorption performance of molecular sieve adsorbents.A fixed-bed desulfurization evaluation device was used to evaluate the performance of molecular sieve in the removal of COS and H₂S from model blast furnace gas.The results show that the selected FAU molecular sieves have better removal performance of COS and H₂S in blast furnace gas than MFI molecular sieves.This is because the former has relatively small silicon to aluminum ratio,large specific surface area,and more effective basic sites.Among the selected eight adsorbents,the FAU-2 adsorbent has the best desulfurization capacity.In the model blast furnace gas,the breakthrough sulfur capacity for COS and H₂S can reach 1.347 and 1.670 g S/100 g adsorbent,respectively.(2)Taking FAU-1,FAU-2,FAU-3 and FAU-4 adsorbents with better desulfurization performance as the research samples,the influence of CO₂ and H₂O on the removal performance of COS and H₂S was investigated.The results show that the CO₂ and H₂O in the model blast furnace gas will reduce the removal performance of COS and H₂S over four adsorbents.Among them,CO₂ has a greater impact on COS removal capacity than H₂O;H₂O has a greater impact on H₂S removal performance than CO₂.The FAU-2 adsorbent with the best desulfurization performance has a breakthrough sulfur capacity of 2.811 and 1.770 g S/100g adsorbent for COS and H₂S without CO₂,1.364 and 21.800 g S/100 g adsorbent for COS and H₂S without H₂O,and 2.938 and 22.184 g S/100 g adsorbent for COS and H₂S without CO₂ and H₂O.(3)Taking FAU-2 adsorbent as the research sample,the influence of working conditions(temperature and gaseous hourly space velocity)on its performance in removing COS and H₂S from blast furnace gas was investigated.The results show that the FAU-2 adsorbent has good adaptability to the working conditions of removing COS.In the working condition range of temperature 60?100 ^oC and gaseous hourly space velocity of 200?1000 h^-1,the FAU-2adsorbent has not obvious change in the removal performance of COS.When temperature is 60^oC and gaseous hourly space velocity is 600 h^-1,the breakthrough sulfur capacity for COS is the largest,which can reach 1.425 g S/100 g adsorbent.The effect of temperature on the removal of H₂S from blast furnace gas by FAU-2 adsorbent is more obvious than that of gaseous hourly space velocity.Within the scope of investigation,its penetration sulfur capacity for H₂S gradually decreases with the increase of temperature,and increases with the increase of gaseous hourly space velocity.When temperature is 60 ^oC and gaseous hourly space velocity is 1000 h^-1,the maximum breakthrough sulfur capacity of H₂S can reach 1.670 g S/100 g adsorbent.In addition,through the distribution of sulfur in the bed after FAU-2 adsorbs COS and H₂S,it is also found that COS can be catalyzed by hydrolysis on the FAU-2 molecular sieve adsorbent and converted to H₂S for further adsorption.