Mechanism of the Water–Gas Shift Reaction Catalyzed by Efficient Ruthenium‐Based Catalysts: A Computational and Experimental Study

Abstract

Supported ionic liquid phase (SILP) catalysis enables a highly efficient, Ru‐based, homogeneously catalyzed water‐gas shift reaction (WGSR) between 100 °C and 150 °C. The active Ru‐complexes have been found to exist in imidazolium chloride melts under operating conditions in a dynamic equilibrium, which is dominated by the [Ru(CO)3Cl3]− complex. Herein we present state‐of‐the‐art theoretical calculations to elucidate the reaction mechanism in more detail. We show that the mechanism includes the intermediate formation and degradation of hydrogen chloride, which effectively reduces the high barrier for the formation of the requisite dihydrogen complex. The hypothesis that the rate‐limiting step involves water is supported by using D2O in continuous catalytic WGSR experiments. The resulting mechanism constitutes a highly competitive alternative to earlier reported generic routes involving nucleophilic addition of hydroxide in the gas phase and in solution.

A review of recent advances in water-gas shift catalysis for hydrogen production

“…Supported ionic liquid phase (SILP) materials have been used to perform reactions at a low-temperature range [75,76]. Stepic et al successfully used this approach to enable a highly effective, homogeneously dispersed Ru-based catalyst to perform WGS reaction in the temperature range of 100°C and 150°C [77].…”

Insights from molecular dynamics simulations on structural organization and diffusive dynamics of an ionic liquid at solid and vacuum interfaces

“…102 A more exciting line of study which is of the importance to interfacial science both from fundamental as well as application point of view is to understand the structural ordering of mono-and bi-layers of the IL depending on how they are prepared from a drop in wetting simulations. In view of the fact that the basic mechanism for the Water-Gas Shift Reaction of Ruthenium-based SILP catalysts was recently established using quantum calculations, 110 we plan to elaborate on this mechanism using MD simulations by including an atomistic description of the IL and to study the dynamics of the gases and this complex incorporated in our S-L-V model system. Supplementary Figures S1 to S10 and full citation for reference 86.…”

Improving the performance of supported ionic liquid phase (SILP) catalysts for the ultra-low-temperature water–gas shift reaction using metal salt additives

“…This kind of an approach has been successfully applied to similar systems. [42][43] Optimizations were carried out without any constraints and vibrational frequencies were determined using the analytical derivatives of the energy as implemented in the AOFORCE module within TURBOMOLE.…”