First-principles Study Of Adsorption Behavior On The Surface Of Lanthanum Ferrite Catalyst In Methane Dissociation Reaction

Natural gas is a combustible mixture of hydrocarbon gases, where the principal constituent is methane. Methane is a greenhouse gas, so the development and utilization of methane is of great significance in terms of environmental protection and solving the world’s energy crisis, etc. In this paper, with DFT, we study the methane and dehydrogenation intermediates adsorption on the lanthanum ferrite LaFeO3(010) of two different magnetic structure, as well as methane and dehydrogenation intermediates with hydrogen adsorption on the lanthanum ferrite LaFeO3(010). The main points are as follows:1. The most stable configuration of CH4, CH3, CH2, CH and C adsorption on the surface of FM and GAFM LaFeO3(010);2. The difference between adsorption energies of H, CH3and C respectively adsorption on the atop of O1and O2of FM and GAFM LaFeO3(010) surface is0.49eV,0.57eV and0.58eV, the difference between adsorption energies of CH2adsorption on the atop of O1and O2of GAFM LaFeO3(010) surface is0.56eV, all have proved that there are two types of oxygen atoms on FM and GAFM LaFeO3(010) surface, O1and O2atom types;3. There are two types of oxygen vacancies on FM and GAFM LaFeO3(010) surface, the difference between energies of oxygen vacancy of FM and GAFM LaFeO3(010) surface is0.63eV and0.60eV respectively;4. The optimized configuration of C adsorption on LaFeO3(010) surface is same as the optimized configuration of CO adsorption on oxygen vacancy of LaFeO3(010) surface, both configurations are C atoms bond with Fe atoms and O atoms, which are from lattice oxygen of the LaFeO3(010) surface in first layer; so when CH4has dissociated to C, and as long as C is bonding with one oxygen atom, then under the slight interference, such as heating, CO will escape from the surface of LaFeO3(010), otherwords, CH4and the lattice oxygen of LaFeO3(010) react to produce CO.