engleski

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

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) 3 Cl 3 ] − 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 D 2 O 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.

ab initio calculations ; reaction mechanisms ; ruthenium ; supported catalysts ; water–gas shift reaction

Funding text We acknowledge funding by the German Research Council, which supports the Excellence Cluster “Engineering of Advanced Materials” at the FAU through its “Excellence Initiative”. We also acknowledge support by the DAAD project Multiscale Modelling of Supported Ionic Liquid Phase Catalysis (2017–2018), as well as the NIC project 11311 at the Jülich supercomputing facilities. R.S., C.R.W., A.- S.S. and D.M.S. gratefully acknowledge financial support from the Croatian Science Foundation project CompSoLS-MolFlex (IP-11- 2013-8238). V.S., M.H. and P.W. gratefully acknowledge financial support from the European Commission within the Horizon2020-SPIRE project ROMEO (grant agreement number 680395). All authors thank Jens Harting for helpful discussions.