(113h) HCl Removal from H2 Gas By Adsorption on Hydrated Ion-Exchanged Zeolites

The removal of hydrogen chloride from hydrogen gas is of great importance for the chemical industry and the environment. In this work, asystematic study is presented on HCl removal from hydrogen gas by adsorption on zeolites, including cation free (i.e. silicalite) and high cation loaded materials (i.e. LTA and 13X zeolites), as well as ion-exchanged zeolites (with alkali, alkaline earth and transition metal ions). The HCl removal performance was studied by breakthrough experimentation with packed beds under high gas velocities, at high pressures (30 bar) and with low HCl concentrations (< 200 ppm). The zeolite screening indicated that the 13X zeolite outperforms the other tested materials. The ion-exchanged X zeolites were extensively characterized via SEM-EDX, XRD, FTIR-ATR, TGA and argon adsorption isotherms. The characterization after HCl adsorption supports the hypothesis that HCl is taken up by the material by forming salt molecules within the zeolite cavities by reaction with the cations and, which is, moreover, enhanced by the presence of pre-adsorbed water. The type of cation present in the zeolite framework structure notably affected the HCl removal adsorption capacity as well as uptake rate The investigation revealed important parameters such as cation radius, atomic mass and electronegativity, which played a noteworthy role in defining the HCl removal performance of ion-exchanged zeolites.