Study on carbon deposition associated with catalytic CH4 reforming by using density functional theory

Density functional theory (DFT) has been applied to investigate the adsorptions of CH4, CH3, CH2, CH, C, H and dissociations CH4, CH3, CH2, CH on the (1 1 1) catalyst surfaces of elementary metals Co bimetals NiFe. More important, the adsorptions and dissociations of those adspecies on elementary metals (Fe, Co, Ni and Cu) and bimetals (NiFe, NiCo and NiCu) have been analyzed. The adsorption energies, activation energies, reaction energies and d-band centers of the catalysts were calculated and their linear correlations were established. The adsorption energy decreases with the d-band center of the catalyst surface shift away from the Fermi level, and thus the increase in activation energy and reaction energy. Therefore, a good catalyst should have a moderate d-band center in CH4/CO2 reforming. This research finds that segregated NiCu is the best one among the eight CH4/CO2 reforming catalysts, Fe, Co, Ni, Cu, NiFe, NiCo, NiCu, and NiCu(S) [segregated NiCu].