Computationally based analysis of the energy efficiency of a CO2 capture process

Abstract

We propose a model for thermodynamic evaluation of the energy efficiency of a CO2 capture in a temperature-pressure swing adsorption. Major parts of this model are computational prediction of the adsorbed gas loading as a function of temperature and partial CO2 pressure, evaluation of the energy expenses under specified conditions for the working capacity, regenerability of the sorbent and purity of the captured CO2, as well as determination of the most optimal desorption conditions in terms of desorption pressure and temperature. The proposed model can be applied for fast evaluation of the energy costs of the CO2 capture process with the use of both experimental or simulation adsorption data with respect to pressure and temperature. We tested this model analyzing data obtained from Grand Canonical Monte Carlo simulations for more than thousand different zeolite structures. Within our approach it is possible to evaluate a theoretical limit of the energy expenses for each specific material and to use the proposed method in screening different structures for the most efficient sorbent material from the energy efficiency point of view under specified requirements for the working capacity of the process, regenerability and purity of captured CO2. We show that setting realistic from the industrial point of view parameters of the CO2 capture cycle leads to substantial reduction of the number of suitable zeolite structures, and to increase of the energy penalty of the CO2 capture compared to evaluations based on minimization of the parasitic energy only.