Critical Admission Temperature of H(2) and CH(4) in Nanopores of Exchanged ERI Zeolites

Due to the nanoporous nature of zeolitic materials, they can be used as gas adsorbents. This paper describes the effect of critical admission temperature through narrow pores of natural ERI zeolites at low levels of coverage. This phenomenon occurs by adsorption of CH(4) and H(2) on pores in natural erionite. The zeolite was exchanged with aqueous solutions of Na(+), Mg(2+), and Ca(2+) salts at different concentrations, times, and temperatures of treatment. Experimental data of CH(4) and H(2) adsorption were treated by the Langmuir equation. Complementarily, the degree of interaction of these gases with these zeolites was evaluated by the evolution of isosteric heats of adsorption. The Ca(2+) and Mg(2+) cations favor the adsorption phenomena of H(2) and CH(4). These cations occupy sites in strategic positions Ca1, Ca2, and Ca3, which are located in the nanocavities of erionite zeolites and K2 in the center of 8MR. Following the conditions of temperature and the exchange treatment, ERICa2 and ERINa3 samples showed the best behavior for CH(4) and H(2) adsorption.