| Hydrogen sulfide（H2S）is a highly toxic acid gas,which is mainly produced from natural gas exploitation,petrol refining,coal gasification and other chemical processes.It will bring huge threats to environment,human health and effective use of energy.Therefore,it is of great significance to develop green and efficient technologies for H2S removal.The existing technologies for H2S removal still have many defects like high energy consumption,volatile loss and equipment corrosion.Ionic liquids（ILs）are a kind of novel green solvents.ILs have many unique advantages,such as extremely low vapor pressure,designable structure,and excellent solvency for many compounds,which qualify them as good acid gas absorbents.Protic ionic liquids（PlLs）are a class of ILs with low cost and convenient synthesis process,whose viscosities are generally low.In this paper,we focus on exploring the application potential of PILs for H2S capture and conversion,and provide ideas and references for the development of new technology for H2S removal.First,we designed and synthesized ten kinds of PILs,which are consisted of three different cations（protonated triethylamine[TEAH],N-ethylmorpholine[NEMH],N-hydroxyethyl morpholin[NHEMH]）,and four different anions（acetate[Ac],propionate[Pro],butyrate[Bu],methoxy acetate[MOA]）.We investigated their densities,viscosities and absorption capacity for H2S,and calculated the thermodynamic parameters of absorption process.The results showed that,[NEMH]and[TEAH]-based acetate,propionate,butyrate PILs exhibit low viscosity（4-15 cP,298.2K）.The absorption of H2S in all samples belong to physical absorption.And their absorption capacity are higher than 0.10 mol H2S/mol IL.among which[NEMH][Bu]shows the highest capacity with 0.156 mol H2S/mol IL.The enthalpy change of[NEMH][Bu]-H2S system is-24.0 kJ/mol,which is favorable for H2S desorption.Second,for the conversion after H2S capture,we explored the performance of six kinds of PILs（N-methylmorpholine acetate[NMMH][Ac],N-methylmorpholine methoxyl acetate[NMMH][MOA],N-ethylmorpholine methoxyl acetate[NEMH][MOA],triethylamine dimalonate[TEAH][dimalonate],N-ethylmorpholine dimalonate[NEMH][dimalonate],N,N-dimethylethanolamine dimalonate[DMEAH][dimalonate]）aqueous solution,and two kinds of organic solvent with high boiling point（1,3-dimethyl-tetrahydro-2（1H）-pyrimidinone DMPU and 1,3-dimethyl-2-imidazolidinone DMI）as liquid phase Claus reaction medium.The results showed that,H2S conversion rate of Claus reaction in all samples are higher than that in diethylene glycol monomethyl ether DGM,a kind of extensively used industrial solvents.Among them,the conversion rate of H2S in[NMMH][MOA]and[NEMH][MOA]aqueous solutions,and DMPU are about 10%higher than that in DGM.In summary,a series of novel PILs xwere designed and their ability to absorb H2S was investigated.In comparison with traditional aprotic ILs.PlLs in this paper have better absorption ability for H2S,and take advantages of simple preparation,low cost and low viscosity.In particular.the PILs mediated liquid phase Claus reaction has been put forward and verified for the first time to achieve the high efficient conversion of H2S.The results in this thesis provide important basis for the development of new capture and conversion processes of H2S. |
