| Hydrogen Sulfide(H2S)is a highly toxic acid gas that not only endangers the health of people,but also causes great corrosion to equipment used in the chemical production process and brings about safety hazards.The existing industrial research on the removal of H2S has problems such as unstable or cannot be regenerated of the desulfurizer.Ionic liquids(ILs)have been widely studied for their low vapor pressure and high stability.However,the existing research on the removal of H2S by ionic liquids has found that conventional ionic liquids only have little absorption to low-pressure of H2S and are only suitable for the crude desulfurization of high-pressure of H2S.The viscosity of functional ionic liquids increased rapidly after adsorption,which not only affected the mass transfer,but also was not conducive to the adsorption experiment.Moreover,the H2S after absorption and analysis needs to be oxidized before it can be used.The oxidizing ionic liquid based on iron-based ionic liquid may produce acidic gas of HCl to pollute the feed gas because of the presence of Cl-.Therefore,this article designed and synthesized a functional ionic liquid,tetraethylammonium metavanadate([N2222][VO3]),used for H2S removal research.1.In this work,[N2222][VO3]was used as the main component to form[N2222][VO3]-[Bmim][BF4]mixture oxidizing and absorbing H2S.By changing the[Bmim][BF4]addition ratio,absorption temperature and H2S partial pressure,the influence of these factors on the H2S absorption effect of oxidized ionic liquid was studied,and the regeneration and repeated absorption effect were also investigated.In[N2222][VO3]-[Bmim][BF4]mixture,the mole absorption of H2S by ILs mixture can be as high as 1.13 mol H2S/mol ILs mixture(n[N2222]VO3:n[Bmim][BF4]=1:6)at the temperature of 50 ℃ and partial pressure of 0.005 MPa.Increasing the temperature is beneficial to increase the absorption rate,but is not good for the absorption capacity.Increasing the partial pressure of H2S gas can increase the absorption rate and capacity at the same time.Furthermore,the research on the regeneration and reusability of the absorbent found that the absorption performance of the absorbent has a limited decline after 5 cycles.The results of 1H NMR,51V NMR and XPS indicated that the valence state of vanadium changed during the absorption process.The XRD characterization and the change of water content before and after absorption prove the formation of elemental sulfur and water during the absorption process.Since VOSO4 also can oxidize and absorb H2S,we speculated that the existence of vanadium changed from VO3-to VO2-to VO3-during absorption and regeneration.2.Because of the low absorption rate of[N2222][VO3]-[Bmim][BF4]mixture for H2S,the influence of the addition of several alkaline solvents on the absorption was investigated,and the results showed that the addition of DMSO can speed up the rate of[N2222][VO3]-[Bmim][BF4]mixture oxidize and absorb H2S,and[N2222][VO3]-DMSO has a better ability to oxidize and absorb H2S.The effects of DMSO addition ratio,absorption temperature,and H2S gas partial pressure on the H2S absorption,regeneration and repeated absorption of[N2222][VO3]-DMSO mixture were investigated.It is found that the addition of DMSO can not only increase the reaction rate and shorten the time required to reach equilibrium,but also increase the molar absorption at equilibrium.In[N2222][VO3]-DMSO mixture(n[N2222][VO3]:nDMSO=1:6),the mole absorption of H2S by mixture can be as high as 1.24 mol H2S/mol mixture at the temperature of 50℃ and partial pressure of 0.005 MPa.And under these conditions,the addition of DMSO increased the H2S removal rate of the ionic liquid from 50%to more than 80%.XRD and XPS characterization showed that the addition of DMSO did not change the absorption mechanism,but promoted the absorption rate of[N2222][VO3]to H2S. |
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