Computational screening-aided design of transition metal-doped CeO2 as NH3-SCR catalysts

Abstract

Transition metal-doped CeO₂ catalysts exhibit great potentials for the selective catalytic reduction (SCR) of nitrogen oxide (NO_x) with NH₃ (NH₃-SCR). However, traditional research mainly relies on a lot of experiments to find out effective catalysts, which wastes a lot of time and resources. Screening out effective CeO₂-based catalysts for low-temperature NH₃-SCR via density functional theory (DFT) calculations is crucial for the rational design and synthesis of efficient catalysts. Herein, transition metal (M = Co, Cr, Cu, Fe, Mn, Mo, Nb, Ni, Ta, Ti, V, and W)-doped CeO₂ catalysts were screened out via accelerated DFT calculations for NH₃-SCR of nitric-oxide (NO) using three theoretical terms; (i) an adsorption energy of NH₃, (ii) an adsorption energy of NO, and (iii) the reaction energies between NO with O₂ and lattice oxygen. The theoretically predicted trend in catalytic performance is as follows: CeO₂-Mn, -Cu, -Mo > CeO₂-Fe, -Co, -Ni, -V, -Cr > CeO₂-W, -Ti > CeO₂-Nb, -Ta. The theoretical prediction was well verified via experimental NH₃-SCR activity of NO at low temperatures (90–300 °C), demonstrating CeO₂-Mo as efficient NH₃-SCR catalyst across a broad temperature range. Temperature-programmed desorption of NH₃ and in situ diffuse reflectance infrared Fourier transforms spectroscopy further indicated that metal doping significantly enhanced the NH₃ adsorption capacity and strength of CeO₂ in the medium- to low-temperature range. Consequently, accelerated DFT calculations provide a useful tool with great potentials for predicting the catalytic performance.

Graphical abstract