Adsorbent Screening for Postcombustion CO2 Capture: A Method Relating Equilibrium Isotherm Characteristics to an Optimum Vacuum Swing Adsorption Process Performance

Abstract

Criteria/correlations proposed in the literature to predict the performance of an adsorbent in a separation process fail in three ways for carbon dioxide (CO2) capture and concentration (CCC) from flue gas: (i) they cannot confirm if the stringent purity–recovery requirements will be met, (ii) the indices rank the adsorbents for a fixed set of operating conditions and not for the best performance for each adsorbent while satisfying the purity–recovery constraints, and (iii) the performance indicator for which the adsorbents are ranked is not explicitly stated, and certainly one index cannot apply for different performance indicators. In this study, a two-step method has been developed for rapid screening of the adsorbents for postcombustion CCC as a function of five easily quantifiable equilibrium isotherm characteristics of the CO2 isotherm, namely, its binary mixture selectivity over N2, equilibrium loading, local slope and nonlinearity at the feed concentration, and Henry’s constant. First, a study has...