Large scale in silico screening of materials for carbon capture through chemical looping

Abstract

Chemical looping combustion (CLC) has been proposed as an efficient carbon capture process for power generation. Oxygen stored within a solid metal oxide is used to combust the fuel, either by releasing the oxygen into the gas phase, or by direct contact with the fuel; this oxyfuel combustion produces flue gases which are not diluted by N₂. These materials can also be used to perform air-separation to produce a stream of oxygen mixed with CO₂, which can subsequently be used in the conventional oxyfuel combustion process to produce sequesterable CO₂. The temperature and oxygen partial pressures under which various oxide materials will react in this way are controlled by their thermodynamic equilibria with respect to reduction and oxidation. While many materials have been proposed for use in chemical looping, many suffer from poor kinetics or irreversible capacity loss due to carbonation, and therefore applying large scale in silico screening methods to this process is a promising way to obtain new candidate materials. In this study we report the first such large scale screening of oxide materials for oxyfuel combustion, utilising the Materials Project database of theoretically determined structures and ground state energies. From this screening several promising candidates were selected due to their predicted thermodynamic properties and subjected to initial experimental thermodynamic testing, with SrFeO_3−δ emerging as a promising material for use in CLC. SrFeO_3−δ was further shown to have excellent cycling stability and resistance to carbonation over the temperatures of operation. This work further advances how in silico screening methods can be implemented as an efficient way to sample a large compositional space in order to find novel functional materials.