| The H2S removal is an inevitable step in the utilization of various hydrocarbon source gases.Any gas source that does not meet the desulfurization standard will cause various hazards to the process,such as corrosion of the pipeline and the electrode,and decrease the activity of the catalyst,which seriously affect Process economy.In addition,considerable economic benefits can also be achieved if H2S in the source is further refined in an efficient manner.Current processes in the application of H2S removal include alkanolamines absorption,low-temperature methanol wash,metal oxides,etc.,which have their own advantages and disadvantages.In this work,the modified strongly basic ion exchange fiber adsorbent,which belongs to a quaternary ammonium ionic liquid,has the characteristics of both ionic liquids and macromolecular polymer,showed strong affinity and stability.In this paper,we put the adsorbent as a research object,and obtained the corresponding research results from the following aspects.The basic properties of adsorbent materials were studied,including charge density,framework structure composition and apparent characteristics.Its skeleton structure was mainly polystyrene,and no obvious pores were observed with uniform thickness.The charge density of the modified adsorbent material is 3.4 mmol/g.We investigated the characteristics of the adsorption process and they fitted well with the deactivation model.With the increase of temperature,adsorption capacity and breakthrough capacity increased slightly before 25℃.But after that,the capacity decreased obviously with increasing temperature.Combined with the initial adsorption rate constants and deactivation rate constants in the deactivated model,it could be concluded that the adsorption process was dominated by the kinetic reaction rate below 25℃,and the dry adsorbent under low temperature had a very strong affinity with H2S.At higher temperatures,the adsorption capacity was dominated by the balance of thermodynamic reactions.In the mean time,a relative humidity of 20%~40%could also promote the breakthrough capacity,while a higher one could reduce the capacity.The process of regeneration with moisture was studied.It can seen that the presence of water greatly affects the regeneration rate,combined with the experimental results and theoretical analysis.Water increased the reaction rate and at the same time shifted the reaction equilibrium toward the desorption reaction.According to the cyclic experiment,the adsorbent material could be steady in 8 cycles.The cyclic adsorption capacity was about 1,1 mmol/g and the breakthrough capacity is about 0.44 mmol/g.It was proved that the stability of the adsorbent material is good.The effect of CO2 on the adsorption of H2S was studied.The experimental results showed that the adsorbent material had a faster reaction rate with H2S than CO2,and they formed a competitive adsorption process.Under the same inlet concentration,the capacity of H2S accounted for a higher proportion,and the relative humidity could increase the proportion of H2S.The capacity of H2S accounted for up to 83%in the condition of 1:1 inlet ratio,which was of great significance to the process efficiency of subsequent treatment of regenerated acid gas mixture.The reaction path of H2S adsorption was studied by DFT method.Through the simplification and optimization of the model,it was concluded that the carbonate anions in the model compound were the most likely sites for H2S adsorption.The reaction mechanism was proton transfer between H2S and CO32-,and the formation of HS-could interact with the adsorbent through ionic bond.In the absence of water,there was no barrier to the reaction of the adsorbent with H2S.In the presence of water,the transition state of the adsorption reaction path produced an energy barrier,and the potential difference between the reactants and the product was greatly reduced,making desorption possible. |
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