Application of the Dubinin–Radushkevich–Astakhov equation to calculate gases isotherms on zeolite adsorbents (on example of H2, CO2, CO, CH4, N2 adsorption on 13X and 5A)

The paper demonstrates the prospects of using an approach for calculating adsorption isotherms of gases on micropore industrial zeolites based on the example of H2, CO2, CO, CH4, N2 adsorption on 13X and 5A zeolites using the Dubinin–Radushkevich–Astakhov (DRA) equation. Experimental adsorption isotherms of H2, CO2, CO, CH4, N2 gases on 13X and 5A zeolites of various manufacturers have been obtained, as well as ranges of the limiting adsorption volume and characteristic adsorption energy have been established. It made it possible to correctly calculate isotherms using the DRA equation in the temperature range 293–323 K and pressure range 0–30 atm. The paper proposes and solves the optimization problem of determining affinity coefficients, which allows the calculation of gas adsorption isotherms on zeolites using only one experimental isotherm of standard gas N2. The mismatch between the experimental isotherms and those calculated by the DRA equation is 14.69% for H2 (maximum) and 1.81% for CO2 (minimum). This approach makes it possible to significantly reduce the number of necessary expensive experiments in comparison with the traditional approach (using the Langmuir equations or equations derived from it), at the same time providing acceptable accuracy for practice.