Industrial & Engineering Chemistry Research, Vol.58, No.28, 12551-12560, 2019
CO2 Conversion Performance of Perovskite Oxides Designed with Abundant Metals
With improved technology, CO2 could be the feedstock for production of renewable fuels. The reverse water-gas shift chemical looping (RWGS-CL) process performs at lower temperatures and higher energy efficiencies than rival methods. Ideal materials must endure reaction conditions, exhibit high activity, and be synthesized from readily available elements. Design and characterization of LaxCa1-xFeyMn1-yO3 perovskite-type oxides resulted in higher CO yields and peak formation rates than previously witnessed in RWGS-CL. Extents of Ca-/Fe-doping presented strong effects on lattice stability (XRD), conversion temperatures, and CO formation (TPO-CO2). Samples calcined at higher temperatures exhibited greater stability and activity but higher conversion temperatures. Vacancy formation energies (DFT) decreased significantly and slightly with increasing Ca and Fe content, respectively, to reflect experimental findings. Surface allocation of metals suggests Fe is redistributed to the surface (XPS) for intensified CO2 conversion with Mn-rich bulk for enhanced oxygen storage capacity and intralattice diffusion.