Astrophysics and Particle Physics

Biography

Biography: Wen Ying Li

Abstract

Carbon deposition, as the main cause of supported Ni catalysts in CH₄/CO₂ reforming, is sensitive to the metal Ni particle size. To explore what’s the reason of the particle size effect during the catalysis process, Ni clusters, Ni₄, Ni₈ and Ni₁₂ which reflect the different cluster thicknesses supported on the MgO (100) slabs, have been adapted to simulate Ni/MgO catalysts. By using density functional theory (DFT), the reaction pathways of CH₄/CO₂ reforming on Nix/MgO (100) models are used to investigate the particle size that might affect the reaction pathway. The reforming mechanisms of CH₄/CO₂ on different Nix/MgO (100) indicate the energy barriers of CH₄ dissociated adsorption, CH dissociation and C oxidation three factors are all declining with the decrease of the Ni cluster size. The Hirshfeld charges analyses of those three steps show only atoms of Nix cluster on bottom or second bottom layer can obtain electrons from the MgO supporter and the main electrons transferring are occurring between adsorbed species and the Ni atoms in surface layer. The Ni atoms of surface layer in small Ni cluster will have more electrons and have better catalytic activity. As a result, the NiO/MgO catalysts with small Ni particle would expose more Ni atoms in contact with the MgO supporter, which might be the reason of metal particle size effect.