Cu carbonyls enhance the performance of Ru-based SILP water–gas shift catalysts: a combined in situ DRIFTS and DFT study

• Published in: Catalysis science & technology Vol. 10; no. 1; pp. 252 - 262
• Main Authors: Blaumeiser, Dominik, Stepić, Robert, Wolf, Patrick, Wick, Christian R., Haumann, Marco, Wasserscheid, Peter, Smith, David M., Smith, Ana-Sunčana, Bauer, Tanja, Libuda, Jörg
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2020
• Subjects: Aluminum oxide; Carbonyls; Catalysts; Copper chloride; Density functional theory; Diffuse reflectance spectroscopy; Dimers; Fourier transforms; Ionic liquids; Ions; Liquid phases; Monomers; Performance enhancement; Shift reaction
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/C9CY01852B

Ru-based supported ionic liquid phase (SILP) catalysts efficiently promote the water–gas shift reaction (WGSR). The addition of CuCl further improves the performance. This is attributed to the formation of labile Cu carbonyl species, which act as CO shuttles in the ionic liquid (IL) phase. We apply in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to monitor the formation of these Cu carbonyls in an imidazolium-based SILP system. To aid the identification of the relevant Cu carbonyls, we perform density functional theory (DFT) calculations. In the present study, we investigate [Ru(CO) 3 Cl 2 ] 2 /CuCl/[C 4 C 1 C 1 Im]Cl/Al 2 O 3 and CuCl/[C 4 C 1 C 1 Im]Cl/Al 2 O 3 with various CuCl : IL ratios. The relevant Cu carbonyls are identified as neutral CuCl monomers and dimers, as well as monoanionic monomers and dimers. Moreover, we demonstrate that the ratio of the individual Cu carbonyl species depends on the CuCl : IL ratio.