Selective removal of H,S from sour gases with microporous membranes. Part II. A liquid membrane of water-free tertiary amines

In the present study the apphcatlon of a hquld membrane for selectlve removal of HsS from gases also contannng COz was mvestlgated The hquld membrane was filled with pure methyl-di-ethanol-amme (MDEA) A theoretical model was developed to descrrbe (a) the chemical equlllbnum between the dissolved gas and MDEA m the membrane and (b) the physical equlhbnum between the solute (CO, and HsS) m the gas and the bqurd phase Expenmentally H,S and COs fluxes were determmed m a setup conslstmg of two well mixed gas phase compartments separated by a flat hqurd membrane. The fluxes were mterpreted with the theoretmal model and separately measured physical constants (solublhty, drffuslvlty and the poroslty/tortuoslty factor of the membrane material) No reactron of CO, with MDEA was observed which 1s attnbuted to the absence of water A weak acid/base mnterackon of HsS and MDEA was found to mcrease the HsS transport through the membrane whrch mcludes higher selectivity This effect is more pronounced at lower partial pressures of HsS