Water–gas shift catalysts based on ionic liquid mediated supported Cu nanoparticles

The sorptive and catalytic properties of alumina supported Cu nanoparticles coated with a thin film of 1-butyl-2,3-dimethyl-imidazolium trifluoromethane sulfonate (BDiMIm) for low-temperature water–gas shift have been explored. For uncoated catalysts, the rate per gram catalyst passed through a maximum with increasing concentration of oxygen on the Cu surface. For reduced catalysts, the presence of oxygen facilitates the dissociation of water, while in excess it decreases the reaction rates due to limiting the reactant concentration. Catalysts coated with ionic liquid showed a higher turn over frequency for the water–gas shift reaction at low temperatures compared to uncoated catalysts and to the best commercial systems, which is attributed to a higher concentration of water in the proximity of the active sites and to the facile decomposition of carboxyl intermediates by the interaction with the ionic liquid. In addition, the presence of the ionic liquid reduces the sorption strength of CO leading to a better balance of the reactants at the surface.