Investigation of the relationship between electronic properties and reactivity of 3DOM LaFe 1 − x Co x O 3 for methane reforming to produce syngas

Abstract

Chemical looping steam methane reforming (CL-SMR) provides a promising pathway to reform methane and to jointly generate high-quality syngas and hydrogen. The key issue is the designing of oxygen carriers (OCs) with high reactivity, good selectivity, and excellent recyclability. The high temperature required for chemical looping reaction also presents challenges in terms of producing stable and anticarbon deposition OCs. Here, we report a three-dimensional ordered macroporous (3DOM) Co-Fe doping perovskites as OCs for CL-SMR, in which the active perovskite phases are equipped with well-ordered wall skeleton in three dimensions. Multiple of characterization techniques such as H2-TPR, XRD, SEM, and XPS were used to characterize the physicochemical properties of OCs. Combining with the tests on fixed-bed reactor, we demonstrated that the 3DOM structures are beneficial to reduce the mass diffusion resistance and to supply more active sites for fuel conversion. The synergetic effects of metal Fe-Co promote the reactivity by increasing the reaction rate and reducing the reaction temperature. These experiment results are further explored by using the first-principle calculations. Differences in the atomic charges and electronic densities show that there are more negative oxygen ions in the doping cells. The substitution of Co increased the transition intensity of Co3d-O2p orbit, and more electrons were excited near Fermi level. These deeper predictions insight into the synergistic mechanism will provide meaningful information for the selecting and designing of oxygen carriers in subsequent study.