Temperature-programmed reduction of unpromoted MoS2-based hydrodesulfurization catalysts: First-principles kinetic Monte Carlo simulations and comparison with experiments

We present the first kinetic Monte Carlo (kMC) simulations of elementary processes corresponding to temperature-programmed reduction (TPR) experiments of unpromoted MoS2-based γ-Al2O3-supported hydrodesulfurization catalysts. The active Mo-edge surfaces in interaction with the gas phase are represented by a one-dimensional periodic array of alternating “top” and “bridge” sites covered by surface species involved in the pathways connecting dissociative adsorption of dihydrogen and associative desorption of hydrogen sulfide. The simulations are monitored by setting partial pressures of H2 and H2S, and temperature or rate of temperature increase. Configuration energies and transition barriers computed by DFT were supplemented by a semi-empirical bond-counting scheme and Brönsted–Evans–Polanyi relationships. Simulated TPR spectra closely match the experimental results.