Dynamic equilibria in supported ionic liquid phase (SILP) catalysis: in situ IR spectroscopy identifies [Ru(CO)xCly]n species in water gas shift catalysis

Bauer, Tanja; Stepić, Robert; Wolf, Patrick; Karawacka, Weronika; Wick, Christian Rainer; Haumann, Marco; Wasserscheid, Peter; Smith, David M.; Smith, Ana-Sunčana; Libuda, Jörg (2018) Dynamic equilibria in supported ionic liquid phase (SILP) catalysis: in situ IR spectroscopy identifies [Ru(CO)xCly]n species in water gas shift catalysis. Catalysis Science and Technology, 8 (1). pp. 344-357. ISSN 2044-4753

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Abstract

Ru-based supported ionic liquid phase (SILP) systems efficiently catalyze the low- temperature water-gas shift reaction (WGSR). While previous studies suggest that Ru-carbonyl species play an important role in the mechanism, detailed knowledge on the catalytically active species is still missing. To identify these carbonyl complexes, we apply in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) in combination with density functional theory (DFT). Investigations of an as-prepared [RuIJCO)3Cl2]2/ [C4C1C1Im]Cl/Al2O3 catalyst indicate splitting of the dimer induced by Cl−. Subsequently, an equilibrium between several [RuIJCO)xCly]n species is established, in which the IL serves as an effectively infinite Cl− reservoir. We find that the major species in the system freshly-prepared from [RuIJCO)3Cl2]2 is indeed [RuIJCO)3Cl3]−. A smaller amount of [RuIJCO)2Cl3]− and chloride-rich species [RuIJCO)2Cl4]2− or [RuCOCl4]2− are also found in the SILP. Similar Ru-carbonyl species are observed during carbonylation of RuCl3/ [C4C1C1Im]Cl/Al2O3, another potential WGSR catalyst. The response of [RuIJCO)3Cl2]2/[C4C1C1Im]Cl/Al2O3 to heating and/or CO dosing was probed in situ and the results confirm the presence of the equilibrium proposed above.

Item Type:	Article
Additional Information:	The authors gratefully acknowledge funding by the German Research Council (DFG), which, within the framework of its "Excellence Initiative" supports the Excellence Cluster "Engineering of Advanced Materials" (www.eam.fau.de) at the Friedrich-Alexander-Universitat Erlangen-Nurnberg" (project EXC 315) (Bridge Funding). T. B. gratefully acknowledges financial support from the "Fonds der Chemischen Industrie". R. S., C. W., A.-S. S. and D. M. S. acknowledge the DAAD project Multiscale Modelling of Supported Ionic Liquid Phase Catalysis (2017-2018), as well as the NIS project 11311 at the Juelich Supercomputing facilities. P. Wa., M. H. and P. Wo. gratefully acknowledges financial support from the European Commission within the Horizon 2020-SPIRE project ROMEO (grand agreement number 680395).
Uncontrolled Keywords:	SILP catalysis ; in situ IR spectroscopy ; [Ru(CO)xCly]n species
Subjects:	NATURAL SCIENCES > Physics
Divisions:	Division of Physical Chemistry
Depositing User:	Ana Sunčana Smith
Date Deposited:	02 Jul 2019 12:49
URI:	http://fulir.irb.hr/id/eprint/4643
DOI:	10.1039/C7CY02199B

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