Properties of Si-modified Pd catalyst for selective hydrogenation of acetylene

Shin, Eun Woo; Choi, Chang Hun; Chang, Ki Soo; Na, Yoon H; Moon, Sang Heup

doi:10.1016/s0920-5861(98)00184-9

Cited by 69 publications

(26 citation statements)

References 15 publications

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“…Active-site isolation increases Pd-Pd distances on the catalyst surface and may lead to only weakly π-bonded acetylene on top of an isolated Pd atom. Furthermore, the sequential hydrogenation of acetylene to ethylene via vinyl and vinylidene intermediates requires a de fore, a reduction of neighbouring palladium sites on the surface should yield preferred hydrogenation of acetylene to ethylene [2,[11][12][13][14][15][16][17].…”

Section: Experimental T Ure Fmmentioning

confidence: 99%

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

Osswald

Kovnir

Armbrüster

et al. 2008

Journal of Catalysis

313

234

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The structurally well-defined intermetallic compounds PdGa and Pd 3 Ga 7 constitute suitable catalysts for the selective hydrogenation of acetylene. The surface properties of PdGa and Pd 3 Ga 7 were characterized by X-ray photoelectron spectroscopy, ion scattering spectroscopy and CO chemisorption. Catalytic activity, selectivity and long-term stability of PdGa and Pd 3 Ga 7 were investigated under different acetylene hydrogenation reaction conditions, in absence and in excess of ethylene, in temperature-programmed and isothermal long-term experiments. Chemical treatment with ammonia solution -performed to remove the gallium oxide layer introduced during the milling procedure from the surface of the intermetallic compounds -yielded a significant increase in activity. Compared to Pd/Al 2 O 3 and Pd 20 Ag 80 reference catalysts, PdGa and Pd 3 Ga 7 exhibited a similar activity per surface area, but higher selectivity and stability. The superior catalytic properties are attributed to the isolation of active Pd sites in the crystallographic structure of PdGa and Pd 3 Ga 7 according to the active-site isolation concept.

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Section: Experimental T Ure Fmmentioning

confidence: 99%

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

Osswald

Kovnir

Armbrüster

et al. 2008

Journal of Catalysis

313

234

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“…However, on the basis of previous results obtained for CO chemisorbed either on supported particles or on single-crystal Pd surfaces one can make some suggestions to interpret the present data. One can propose that CO adsorbs on Pd in four modes, depending on both the site for adsorption and the CO-CO interactions: they would correspond to linear (around 2,075 cm -1 ), compressedbridged (around 1,970 cm -1 ), isolated bridged (nearby 1,920-1,910 cm -1 ) and tri-coordinated (&1,830 cm -1 ) bonds [13,23]. It is also tempting to interpret the spectra in terms of CO adsorbed on the different facets and/or on the edges present on the Pd particles, as proposed by Freund et al [22].…”

Section: Ir Of Co Adsorbed As a Probementioning

confidence: 99%

“…However it was shown that its activity and selectivity can be strongly influenced by the metal dispersion, the nature of the support and the preparation method [9][10][11]. Moreover, it is known that the presence of additives can modify strongly the properties of Pd catalysts for this reaction [7,12,13].…”

Section: Introductionmentioning

confidence: 99%

Surface Modification of Pd/α-Si3N4 Catalysts Through the Solvent Used During Synthesis. Implications on the CO Chemisorption Properties and Catalytic Performances

2009

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Palladium catalysts supported on a-Si 3 N 4 were prepared by impregnation with Pd(II)-acetate dissolved either in toluene or in water. The mean metal particle size of *0.5 wt% Pd catalysts was similar (*5 nm) and independent of the way of preparation. Nevertheless, the two catalysts present very different chemisorption behaviour chemisorptive and catalytic properties. Fourier transformed infrared (FTIR) spectra of adsorbed CO at different temperatures (ranging from room temperature to 300°C) show a very different behaviour for both catalysts. While the CO adsorption states on the Pd/a-Si 3 N 4 prepared in toluene are very similar to those generally measured for silica and/or alumina supported palladium catalysts, CO chemisorbs less strongly on Pd/a-Si 3 N 4 prepared in water and on different adsorption sites. The Pd/a-Si 3 N 4 catalyst obtained by aqueous impregnation is much less efficient for the methane total oxidation. It is less active and less stable: it deactivates strongly after 3 h on stream at 650°C. The two catalysts present about the same activity for the 1,3-butadiene hydrogenation after stabilisation at 20°C. But, the catalyst prepared in water shows a much better selectivity to butenes. The results are discussed in terms of the possible migration of silicon atoms from the silicon nitride support to the surface of the palladium particles, when the catalyst is prepared in water. This is not the case when prepared in an organic solvent.

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“…Catalyst surfaces that expose only isolated activesites exhibit a reduced number of possible adsorption geometries. Acetylene molecules will preferably be weakly π-bonded and the amount of di-σ-bonded acetylene as well as adsorbed ethylene and ethylidyne species will be reduced [7][8][9][10][11][12][13][14][15][16], leading to a smaller amount of oligomerisation products. Therefore, restricting the size of the active sites in a palladium containing hydrogenation catalyst and thereby preventing the formation of ensembles of neighboring Pd atoms on the surface -so-called active-site isolation -may increase the catalyst selectivity and long-term stability in acetylene hydrogenation.…”

Section: Introductionmentioning

confidence: 99%

Palladium–gallium intermetallic compounds for the selective hydrogenation of acetylenePart I: Preparation and structural investigation under reaction conditions

Osswald

Giedigkeit

Jentoft

et al. 2008

Journal of Catalysis

285

221

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The intermetallic compounds PdGa and Pd 3 Ga 7 are introduced as selective catalysts for the hydrogenation of acetylene. Single phase PdGa and Pd 3 Ga 7 can readily be prepared by the appropriate thermal treatment of the stoichiometric mixtures of the corresponding elements. The initial low surface areas of the as-prepared materials can be increased by careful mechanical treatment without decomposition. Detailed investigations of PdGa and Pd 3 Ga 7 by DSC/TG, in situ powder X-ray diffraction and in situ X-ray absorption spectroscopy during thermal treatment under various inert or reactive gas atmospheres showed a high thermal stability. The long-range and short-range order in the crystal structures remained intact up to temperatures of about 600 K. Neither phase transitions nor decomposition were detectable. In addition to high thermal stability -preserving the active-site isolation under reaction conditions -no incorporation of hydrogen or carbon in the intermetallic compounds under reducing conditions was observed. Besides being interesting model systems, palladium gallium intermetallic compounds are promising candidates for the application as highly selective hydrogenation catalysts.

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Properties of Si-modified Pd catalyst for selective hydrogenation of acetylene

Cited by 69 publications

References 15 publications

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

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

Surface Modification of Pd/α-Si3N4 Catalysts Through the Solvent Used During Synthesis. Implications on the CO Chemisorption Properties and Catalytic Performances

Palladium–gallium intermetallic compounds for the selective hydrogenation of acetylenePart I: Preparation and structural investigation under reaction conditions

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