Adsorption breakthrough and cycling stability of carbon dioxide separation from CO2/N2/H2O mixture under ambient conditions using 13X and Mg-MOF-74

Abstract

Carbon dioxide and storage is an efficient method to reduce the emitted CO2 from the burning of fossil fuels. Zeolite-based materials are conventional adsorbents used to adsorb some gasses involving carbon dioxide. Mg-MOF-74 is an eminent reticular material among adsorbents due to its good CO2 capacity at low pressures (10–20 kPa). In this study, an experimentally validated model is used to report the H2O effect on CO2 separation using 13X and Mg-MOF-74 under ambient conditions. A computational model has been developed using ANSYS Fluent program linked by user-define-function (written in C). The adsorption breakthrough results show that a humid CO2/N2 mixture, under 300 K, 86% RH, 101.3 kPa, could slightly reduce the CO2 adsorption capacity by about 0.05% and 6% for 13X and Mg-MOF-74, respectively (at CO2 adsorption breakthrough saturation). Regardless of these reductions, Mg-MOF-74 has better adsorption capacity, even under humid ambient conditions, by about 5.77 mmol/g in a comparison to 2.27 mmol/g for 13X, respectively.Cycling stability over more than 90 cycles is also simulated; and shows that, a dehydration process is recommended to be carried out before the CO2 separation process for efficient energy consumption and sustainable adsorbents. The total recyclable amounts of adsorbed CO2 are about 0.94 and 3.07 mmol/g for 13X and Mg-MOF-74, respectively, under 101.3 kPa adsorption, 2 kPa desorption, 86% relative humidity, and 298 K. The cyclic CO2 separation is found to be a robust method more than the breakthrough separation to evaluate the real adsorption capacities.