Theoretical Study of Inorganic Carbonaceous Species Reaction with the Surfaces of BaTiO3(001)

Due to the variety of component elements and their high chemical stability at elevated temperatures, various perovskite oxide materials have been used to replace catalyst containing precious metals as oxidation catalysts or oxygen-activated catalysts (1). Additionally, because of their oxygen mobility through the material the C accumulation is not promoted. Such is the case of the resistance towards C deposition of Ni/BaTiO₃-Al₂O₃ when employed as catalyst for low temperature dry reforming of CH₄ (2). During the CH₄ reforming, the C deposition is caused mainly due the CH₄ decomposition or the CO disproportionation reaction that will lead to the formation of CO₂ and C. On the other hand, one of the drawbacks of some perovskite materials such as BaTiO₃ is that in the presence of CO₂ the formation of a localized stable carbonate phase on the surface is possible (3). This carbonate phase will affect not only the catalytic activity of the material, but also may influence in its electronic properties. In this study the density functional theory (DFT) will be employed to analyze from a theoretical point of view the interaction of CO₂ and the CO disproportionation reaction on the surfaces of BaTiO₃(001). Our first approach with the BaO-terminated surface revealed that the CO molecule chemisorbs on the surface O atom. Additionally, if another CO molecule from the gas phase will interact with the already adsorbed CO molecule (Eley-Rideal reaction mechanism), the formation of trioxydehydroethene showed high spontaneity and the least stable but still probable to occur is the formation of CO₂ and C that chemisorbs on top of an O atom (disproportionation reaction).  Moreover, for the CO₂ reaction with the BaO-terminated surface, the formation of CO₃ anion showed to be quite stable. Furthermore, the CO₂ reaction and CO disproportionation reaction will be also analyzed for the TiO₂-terminated surface.

References

1. J. T. S. Irvine, in Perovskite Oxide for Solid Oxide Fuel Cells, T. Ishihara, Ed., p. 167, Springer, Fukuoka (2008).
2. X. Li, Q. Hu, Y. Yang, Y. Wang, and F. He, Appl. Catal. A, 413– 414, 163, (2012).
3. M. Wegman, L. Watson, A. Hendry, J. Am. Ceram. Soc., 87, 371 (2004).