Palladium–gallium intermetallic compounds for the selective hydrogenation of acetylenePart II: Surface characterization and catalytic performance

Osswald, Jürgen; Kovnir, Kirill; Armbrüster, Marc; Giedigkeit, Rainer; Jentoft, Rolf E.; Wild, Ute; Grin, Yuri; Schlögl, Robert

doi:10.1016/j.jcat.2008.06.014

Cited by 304 publications

(252 citation statements)

References 61 publications

(73 reference statements)

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“…To understand the excellent heterogeneous catalytic properties of the intermetallic compound PdGa [6][7][8] in detail, large single crystals are necessary to conduct surface investigations. According to references [9] and [10], PdGa crystallizes in the FeSi type of structure [11,12].…”

Section: Discussionmentioning

confidence: 99%

Refinement of the crystal structure of palladium gallium (1:1), PdGa

Armbrüster¹,

Borrmann²,

Wedel³

et al. 2010

Zeitschrift Für Kristallographie - New Crystal Structures

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PdGa, cubic, P2 13( no. 198), a =4.89695(6) Å, V =117.4 Å 3 , Z =4,R gt(F) =0.024, wRref(F 2 ) =0.035, T =295 K. Source of materialLarge single crystals of PdGa were obtained by Czochralski growth from the melt as described in [1]. The melt consisted of Pd (99.9 %, ChemPur) and Ga (99.99 %, ChemPur) in an atomic ratio of 45:55. The metals were pre-reacted in glassy carbon crucibles under inert argon atmosphere in ahigh-frequency induction furnace. Single crystals used in this study were obtained from the bottom of the as grown Czochralski crystal and were annealed at 800°Cfor 24 hindynamic vacuum at 10 -6 mbar prior to the X-ray diffraction experiments. For the lattice parameter determination a small part of the bottom of the large crystal was crushed and annealed as described above. WDXS measurements were performed on aC AMECA SX100 (W filament, 25 kV) with Pd50Ga50 (by chemical analysis via ICP-OES) as standard. Experimental detailsSingle crystal data were collected using aRigaku R-axis SPIDER diffractometer with monochromated Ag K a radiation. Determination and refinement of the crystal structure were performed with the SHELX-97 software [2]. Spence [3] defined the two absolute structures of the FeSi type as form A( Fe in 4a with x = 0.1358, Si in 4a with x =0.844) and form B(Fe in 4a with x = 0.8642, Si in 4a with x =0.156). Models of both absolute structures were refined for PdGa without twin model and resulted in considerable differences in R gt,A =0 .028 and Rgt,B =0 .040, respectively. Further refinement of form Aa si nversion twin resulted in aF lack parameter of 0.05(1), confirming the proper parameter set. Refining site occupancy for both atoms resulted in fully occupied sites within one e.s.d. This excludes mutual site occupation in the crystal as is expected due to the covalent interactions in the compound [4].

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Section: Discussionmentioning

confidence: 99%

Refinement of the crystal structure of palladium gallium (1:1), PdGa

Armbrüster¹,

Borrmann²,

Wedel³

et al. 2010

Zeitschrift Für Kristallographie - New Crystal Structures

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“…Pd and Ga can form a number of intermetallic compounds (IMC) and/or alloys; e.g., Pd 2 Ga, PdGa, Pd 3 Ga 7 , and PdGa 5 were reported in literature [20].Metallurgically prepared, unsupported intermetallic bulk materials have been studied in recent years, showing excellent catalytic properties for selective hydrogenation of acetylene in excess ethylene [21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

In situ study of the formation and stability of supported Pd2Ga methanol steam reforming catalysts

Haghöfer

Föttinger

Girgsdies

et al. 2012

Journal of Catalysis

105

138

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Pd/Ga2O3 methanol steam reforming (MSR) catalysts were characterized in detail by utilizing a range of in situ techniques of varying surface sensitivity. Correlating the nature of the intermetallic Pd-Ga compound (IMC; formed upon reduction) with the corresponding activity/selectivity revealed pronounced differences. Generally, a dynamic response of the catalyst surface to the surrounding gas environment was observed. Special attention was paid to the bulk and surface stability of the Pd-Ga IMCs. Whereas the bulk was stable in O2, decomposition of the surface occurred resulting in a partial coverage by GaxOy islands. In addition, we focused on the formation mechanism of undesired CO and were able to identify the reasons limiting the selectivity to MSR. We observed a detrimental effect of CO on the selective Pd-Ga intermetallic compound, causing partial decomposition of the IMC to metallic Pd at the surface. Consequently, patches of Pd metal are present under reaction conditions, catalyzing the unwanted parallel methanol decomposition reaction.

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“…6, Pd 3 Bi/SiO 2 was found to be promising because it gave high selectivity of 80 C-% at 95% acetylene conversion in the presence of excess amount of ethylene. 20) Osswald et al 4) also reported that unsupported PdGa and Pd 3 Ga 7 IMCs were more selective than Pd/Al 2 O 3 .…”

Section: Hydrogenationmentioning

confidence: 98%

“…4,5) We started to work on the catalysis by IMCs in 1996 6) with bulk Co-based compounds. Then we succeeded to prepare single-phase particles of Ni-Sn IMCs having their diameter smaller than 15 nm on silica gel.…”

Section: Introductionmentioning

confidence: 99%

Intermetallic Compound Nanoparticles Dispersed on the Surface of Oxide Support as Active and Selective Catalysts

Komatsu

Furukawa

2015

Mater. Trans.

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Preparation of nanoparticles of intermetallic compounds and their application to various catalytic reactions are summarized. On the surface of silica support, single-phase nanoparticles of intermetallics with various combinations of elements were obtained by co-impregnation and/or successive impregnation procedures. On alumina support, its strong interaction with metal species requires another preparation procedure, liquidphase reduction, to obtain intermetallic nanoparticles with high phase purity. Most of the particles formed on both supports had diameters of 3³20 nm. Thus prepared intermetallic nanoparticles were used as catalysts for various reactions such as H 2 -D 2 equilibration, selective hydrogenation, dehydrogenation, oxidation and isomerization. The catalytic activity and selectivity of nanoparticles differed from each other depending on the combination and composition of two elements. In some cases, the intermetallic catalysts gave much higher activity and/or selectivity than their component monometallic catalysts. The unique catalytic properties of intermetallic compounds were discussed in terms of the electronic and geometric factors compared with pure metals.

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Palladium–gallium intermetallic compounds for the selective hydrogenation of acetylenePart II: Surface characterization and catalytic performance

Cited by 304 publications

References 61 publications

Refinement of the crystal structure of palladium gallium (1:1), PdGa

Refinement of the crystal structure of palladium gallium (1:1), PdGa

In situ study of the formation and stability of supported Pd2Ga methanol steam reforming catalysts

Intermetallic Compound Nanoparticles Dispersed on the Surface of Oxide Support as Active and Selective Catalysts

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