545752 Supported Liquid Metals - a New Class of Robust Dehydrogenation Catalysts

Monday, June 3, 2019: 2:42 PM
Texas Ballroom A (Grand Hyatt San Antonio)
Nicola Taccardi1, Mathias Grabau2, Jonas Debuschewitz1, Monica Distaso3, Marco Brandl4, Rainer Hock4, Florian Maier2, Christian Papp2, Jannis Erhard5, Christian Neiss5, Wolfgang Peukert3, Andreas Görling5, Moritz Wolf1, Marco Haumann1, Hans-Peter Steinrück2 and Peter Wasserscheid1,6, (1)Institute of Chemical Reaction Engineering, University of Erlangen-Nuremberg, Erlangen, Germany, (2)Institute of Physical Chemistry II, University of Erlangen-Nuremberg, Erlangen, Germany, (3)Institute of Particle Technology, University of Erlangen-Nuremberg, Erlangen, Germany, (4)Institute of Crystallography and Structural Physics, University of Erlangen-Nuremberg, Erlangen, Germany, (5)Institute of Theoretical Chemistry, University of Erlangen-Nuremberg, Erlangen, Germany, (6)Helmholtz Institute Erlangen-Nürnberg for Renewable Energy, Erlangen, Germany

Our contribution demonstrates that Supported Catalytically Active Liquid Metal Solutions (SCALMS) offer the potential for new and unusual catalytic reactivity in propane dehydrogenation. SCALMS are composed of catalytically active liquid alloy droplets on a porous support.[1] In contrast to conventional supported liquid phase catalysis, the catalytic reaction in SCALMS occurs only at the highly dynamic liquid metal/gas interface, as the liquid metal does not provide any relevant reactant solubility.

Figure 1. a) SEM image of Pd-Ga decorated porous glass and schematic representation of the microscopic nature of the material. b) Catalytic performance of standard heterogeneous and PdGa SCALMS catalysts in butane dehydrogenation.

Recently, we reported the use of Ga-rich Ga/Pd mixtures (Ga/Pd ratio> 10) on porous glass in the highly endothermal n-butane dehydrogenation [1]. The liquid nature of the supported alloy droplet under the reaction conditions was confirmed through a combination of XRD, SEM, XPS, and ab initio dynamics calculations. Most remarkably, these SCALMS materials outperformed commercial dehydrogenation catalysts (Pt/Al2O3, Cr2O3/Al2O3) without any material or process optimisation. The most remarkable finding, however, was that coking, the typical deactivation mechanism for this type of high temperature hydrocarbon chemistry under reductive conditions [2-4] is largely suppressed with SCALMS systems. As explanation for this unexpected behaviour our molecular dynamics (MD) calculations suggested that the topmost layer of the Ga-rich Ga/Pd alloy is depleted in Pd, but the layer directly underneath is enriched.

[1]  N. Taccardi, M. Grabau, et int., C. Papp, W. Peukert, A. Görling, H.-P. Steinrück, P. Wasserscheid, Nat. Chem. 9 (2017) 862-867.

[2]   J.R. Rostrup-Nielsen, J. Catal. 1984, 85, 31.

[3]   V.L. Kuznetsov, A.N. Usol’tseva, Y.V. Butenko, Kin. Catal. 2003, 44, 726.

[4]   J.J.H.B. Sattler, J. Ruiz-Martinez, E. Santillan-Jimenez, B.M. Weckhuysen, Chem. Rev. 2014, 114(20), 10613.

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