Studies On LaBO₃Perovskite Catalyst With First Principles

Accelerating the development of SO2removal technologies as well as takingeffective measures to control and to govern SO2pollution have become one ofcommon concerns all over the world. Of numerous desulfurization technologies, theCatalytic reduction desulfurization is also a technology with great potential and brightprospects. A large number of studies have shown that LaBO3perovskite typecomposite oxides have good performances on catalytic reduction reactions, which arederived from their unique structures. As a result, understanding their structure fromthe microscopic viewpoint has important guiding significance for experimental studiesof LaBO3catalyst.This paper established the bulk models of LaBO3(B=Co, Fe, Mn, Cr) catalysts.The optimized reasonable geometric model is established by exchange correlationfunction as well as pseudo-potential function tests which helped slect suitable fuctionsand files. By analyzing their band structure, Density of States and Partial Density ofStates, we archieved conclusions as follows: firstly, the band gap values areassociated with the catalytic activity of catalysts, lower the bandgap value is, easierelectrons span bandgap, and the catalytic activity improves as a result. Secondly,electrons of B-d orbital affect the catalytic activity of catalysts. Thirdly, stability ofLaBO3system mainly comes from BO6octahedron and the A site is easily to bedoped for weak interations between element A and O.Catalytic reduction of SO2by CO is maily performed in the surface of the catalyst，so gas adsorption ability of catalyst is one of the key factors that influence thecatalytic activity. Our previous studies found that CO adsorption ability of Perovskitecatalyst is stronger than that of SO2.As a result, adsorption ability of SO2becomes thekey indicators of catalyst activity. This article calculated the SO2of differentadsorption configurations adsorptioned on LaCrO3(100) surface using first principles,founding that the spontaneous adsorption configuration is the way Cr elements ofLaCrO3(100) surface interacts with O element of SO2, the bridge adsorptionconfiguration requires additional energy and adsorption possibility of Cr elementsfrom LaCrO3(100) surface interacts with S element of SO2is very small. We alsofound that before and after adsorption the surface relaxation trend changes indicatingthat SO2adsorption has changed the surface structure. Interactions between Cr ofsurface and O of SO2is mainly hybrid interactions between the d orbitals of Cr and O-p orbital. All in all, we predicted that to improve the activity of eletrons of B-dorbital is in favour of improving SO2adsorption ability on surface of LaBO3,correspondingly is in favour of improving catalytic activity of LaBO3which is accordwith conclusions of previous experiments results.