High-pressure sour gas adsorption on zeolite 4A

Abstract

In an effort to measure self-consistent adsorption isotherms for sour gas species on zeolite 4A, two high-pressure manometric adsorption instruments have been built for measurement up to p = 225 bar. A comparison of CO2 adsorption up to p = 200 bar on Fitrasorb F400 activated carbon shows the reliability of these instruments. For the purpose of this work, high purity zeolite 4A was synthesized and characterized by SEM/EDX, XRD, FTIR, and DLS. High-pressure adsorption isotherms (absolute and excess) for CO2, COS, CH4 and H2S adsorption on zeolite 4A have been reported for T = 0, 25, and 50 °C along with corresponding parameters for the modified Toth isotherm. The adsorption of COS on zeolite 4A showed some unexpected results, where (i) lower temperature isotherms were dominated by size effects, (ii) the adsorption capacity was half that of CO2 or H2S, and (iii) computational calculations for HOMO bond orientation indicate that COS should be excluded from zeolite 4A, despite the experimental results.