Predictive Guide for Collective CO2 Adsorption Properties of Mg-Al Mixed Oxides

Abstract

Although solid adsorption processes offer attractive benefits, such as reduced energy demands and penalties compared with liquid absorption processes, there are still pressing needs for solid adsorbents with high adsorption capacities, thermal efficiencies, and energy-intensive regeneration in gas-treatment processes. The CO2 adsorption capacities of layered double oxides (LDOs), which are attractive solid adsorbents, have an asymmetric volcano-type correlation with their relative crystallinities. Furthermore, new collective adsorption properties (adsorption capacity, adsorptive energy and charge-transfer amount based on the adsorbent weight) are proposed based on density functional theory (DFT) calculations and measured surface areas. The correlation of these collective properties with their crystallinities is in good agreement with the experimentally measured CO2 adsorptive capacity trend, providing a predictive guide for the development of solid adsorbents for gas-adsorption processes.