High-throughput theoretical optimization of the selective reduction reaction of NO with NH3 on metal-organic frameworks

Abstract

MOFs have exhibited excellent catalytic activity for selective catalytic reduction of nitrogen oxides (NOx) with NH3 (NH3-SCR). However, the exploration of stable, eco-friendly and highly efficient MOFs for NH3-SCR still lacks theoretical guidance, and the theoretical mechanism for the catalytic activity should be clarified, especially with regards to the hitherto unclear effect of the active sites. Herein, high-throughput computational methods based on first-principles calculations were adopted to screen superior MOFs catalysts for NH3-SCR, focusing on the coordination environment of unsaturated metal active sites. In this study, a density functional theory (DFT) calculation was carried out for the thermodynamics of NH3-SCR reaction simulation for 231 types of MOFs consisting of different metal sites and ligand atoms. The Mo-MOF (ε(trim)4/3) was found to exhibit the lowest over potential of 0.29 V among all of the MOFs we studied. The electronic structure analysis further reveals that ε(trim)4/3 has a suitable adsorption capacity for NH2 fragment and H atom, which leads to a good catalytic effect. And the hybridization at lower energy level between the orbitals of O atom and Mo site is the origin of preferable SCR activity of Mo-MOF. This computational work provides an effective catalyst screening strategy to guide future experimental studies.