Impregnated and Co-precipitated Pd-Ga2O3, Pd-In2O3 and Pd-Ga2O3-In2O3 Catalysts: Influence of the Microstructure on the CO2 Selectivity in Methanol Steam Reforming

Christoph Rameshan; Harald Lorenz; Marc Armbrüster; Igor Kasatkin; Bernhard Klötzer; Thomas Götsch; Kevin Ploner; Simon Penner

doi:10.1007/s10562-018-2491-4

Impregnated and Co-precipitated Pd-Ga₂O₃, Pd-In₂O₃ and Pd-Ga₂O₃-In₂O₃ Catalysts: Influence of the Microstructure on the CO₂ Selectivity in Methanol Steam Reforming

Catal Letters. 2018;148(10):3062-3071. doi: 10.1007/s10562-018-2491-4. Epub 2018 Aug 3.

Authors

Christoph Rameshan^{1

2

3}, Harald Lorenz¹, Marc Armbrüster⁴, Igor Kasatkin^{2

5}, Bernhard Klötzer¹, Thomas Götsch¹, Kevin Ploner¹, Simon Penner¹

Affiliations

¹ 1Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria.
² 3Department of Inorganic Chemistry, Fritz-Haber Institute of the Max-Planck-Society, Faradayweg 4-6, 14195 Berlin, Germany.
³ 5Present Address: Institut für Materialchemie, Technische Universität Wien, Getreidemarkt 9/BC/01, 1060 Vienna, Austria.
⁴ 2Institute of Chemistry, Technical University Chemnitz, Straße der Nationen 62, 09111 Chemnitz, Germany.
⁵ 4Present Address: Saint Petersburg State University, Universitetskaya nab. 7-9, St. Petersburg, Russia 199034.

Abstract

Abstract: To focus on the influence of the intermetallic compound-oxide interface of Pd-based intermetallic phases in methanol steam reforming (MSR), a co-precipitation pathway has been followed to prepare and subsequently structurally and catalytically characterize a set of nanoparticulate Ga₂O₃- and In₂O₃-supported GaPd₂ and InPd catalysts, respectively. To study the possible promoting effect of In₂O₃, an In₂O₃-doped Ga₂O₃-supported GaPd₂ catalyst has also been examined. While, upon reduction, the same intermetallic compounds are formed, the structure of especially the Ga₂O₃ support is strikingly different: rhombohedral and spinel-like Ga₂O₃ phases, as well as hexagonal GaInO₃ and rhombohedral In₂O₃ phases are observed locally on the materials prior to methanol steam reforming by high-resolution transmission electron microscopy. Overall, the structure, phase composition and morphology of the co-precipitated catalysts are much more complex as compared to the respective impregnated counterparts. However, this induces a beneficial effect in activity and CO₂ selectivity in MSR. Both Ga₂O₃ and In₂O₃ catalysts show a much higher activity, and in the case of GaPd₂-Ga₂O₃, a much higher CO₂ selectivity. The promoting effect of In₂O₃ is also directly detectable, as the CO₂ selectivity of the co-precipitated supported Ga₂O₃-In₂O₃ catalyst is much higher and comparable to the purely In₂O₃-supported material, despite the more complex structure and morphology. In all studied cases, no deactivation effects have been observed even after prolonged time-on-stream for 12 h, confirming the stability of the systems.

Graphical abstract: The presence of a variety of distinct supported intermetallic InPd and GaPd₂ particle phases is not detrimental to activity/selectivity in methanol steam reforming as long as the appropriate intermetallic phases are present and they exhibit optimized intermetallic-support phase boundary dimensions.

Keywords: Catalysis; Catalyst activation; High-resolution electron microscopy; Hydrogen reduction; Intermetallic compound; X-ray diffraction.