Formation and Characterization of PdZn Alloy: A Very Selective Catalyst for Alkyne Semihydrogenation

Tew, Min Wei; Emerich, Herman; Bokhoven, Jeroen A. van

doi:10.1021/jp1103164

Cited by 157 publications

(178 citation statements)

References 54 publications

(66 reference statements)

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“…Kinetic simulations also show that the classical explanation of selectivity as originating from the displacement of ethylene by acetylene in acetylene hydrogenation does not fully describe the system because acetylene surface coverage is always low. Similar conclusions were derived from DFT calculationsthe presence of Pb in reactions catalysed by Pd decreases the adsorption energies of ethyne and ethene, rendering Pd atoms situated close to the Pb almost inactive in full hydrogenation [83,84].…”

Section: Irreversible Adsorbatessupporting

confidence: 79%

The Reduction of Alkynes Over Pd-Based Catalyst Materials - A Pathway to Chemical Synthesis

Ao¹,

Sk²

2017

J Chem Eng Process Technol

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Many reactions, including selective hydrogenation of alkynes, take place on solid surfaces. These reactions are vital in many areas of industry including the manufacture of polymers and fine chemicals such as vitamins, fragrances, and drugs. The choice of a catalyst is a trade-off between activity, selectivity and costs. Palladium-based heterogeneous catalysts are traditionally used for these processes as they provide the activation of hydrogen at room temperatures and offers reasonable selectivity, but these catalysts have a number of practical drawbacks. This review discusses recent research work in the selective hydrogenation of alkynes on palladium-based catalysts, emphasises the mechanism and catalytic materials and important applications including alkyne removal from gasphase alkene precursors for polymer synthesis and liquid phase selective hydrogenation for the synthesis of fine chemicals. Langmuir-Hinshelwood reaction kinetic models, reaction intermediates, formation of carbonaceous layer, the nature of active sites and the effects of reversible and irreversible adsorbates over Pd surface are discussed as well as the factors affecting catalyst activity and selectivity and how these can be optimised in synthetic protocols for these reactions.

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Section: Irreversible Adsorbatessupporting

confidence: 79%

The Reduction of Alkynes Over Pd-Based Catalyst Materials - A Pathway to Chemical Synthesis

Ao¹,

Sk²

2017

J Chem Eng Process Technol

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“…The ZnO support, in contrast to traditional supports, such as carbon or refractory oxides (SiO 2 , Al 2 O 3 , or TiO 2 ), forms Pd-Zn intermetallic compounds, which affect the relative adsorption energies of alkynes and alkenes and result in an increased alkene selectivity [51,56].…”

Section: Effect Of Liquid Flow Ratesmentioning

confidence: 99%

Process Intensification of Alkynol Semihydrogenation in a Tube Reactor Coated with a Pd/ZnO Catalyst

2017

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Semihydrogenation of 2-methyl-3-butyn-2-ol (MBY) was studied in a 5 m tube reactor wall-coated with a 5 wt % Pd/ZnO catalyst. The system allowed for the excellent selectivity towards the intermediate alkene of 97.8 ± 0.2% at an ambient H 2 pressure and a MBY conversion below 90%. The maximum alkene yield reached 94.6% under solvent-free conditions and 96.0% in a 30 vol % MBY aqueous solution. The reactor stability was studied for 80 h on stream with a deactivation rate of only 0.07% per hour. Such a low deactivation rate provides a continuous operation of one month with only a two-fold decrease in catalyst activity and a metal leaching below 1 parts per billion (ppb). The excellent turn-over numbers (TON) of above 10 5 illustrates a very efficient utilisation of the noble metal inside catalyst-coated tube reactors. When compared to batch operation at 70 • C, the reaction rate in flow reactor can be increased by eight times at a higher reaction temperature, keeping the same product decomposition of about 1% in both cases.

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“…This Kubelka-Munk/a.u. process is facilitated by metallic palladium, which simultaneously participates in the formation of PdZn alloys [3][4][5][28][29][30]. It is interesting that reduction of ZnO and thus formation of PdZn start at lower temperature in Pd/ ZnO-AOT sample.…”

Section: Resultsmentioning

confidence: 99%

“…In recent years, a lot of attention has been paid to the development of supported palladium alloy catalysts, such as PdZn, PdIn or PdGa, showing their superior activity and selectivity in the hydrogenation of carbon oxides to methanol, water gas shift reaction, methanol steam reforming or hydrogenation of alkenes and alkadienes [3][4][5][6][7]. The impregnation method from aqueous solutions is one of simplest ways of the preparation of catalysts and has been often used for the synthesis of alumina-, silica-or carbon-supported palladium catalysts.…”

Section: Introductionmentioning

confidence: 99%

Application of microemulsion method for development of methanol steam reforming Pd/ZnO catalysts

Pawlonka

Gac

Greluk

et al. 2016

J Therm Anal Calorim

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Thermal decomposition of palladium acetylacetonate adsorbed on zinc oxide (ZnO), and the formation of palladium oxide (PdO) and palladium zinc alloy (PdZn) phases were studied. Two types of ZnO supports were prepared by the microemulsion method using different surfactants, i.e. hexadecyltrimethylammonium bromide (CTAB) and (Bis(2-ethylhexyl) sulfosuccinate sodium salt, AOT). The nanoparticles of ZnO synthesized in the presence of CTAB surfactant showed higher specific surface area, smaller crystallite size and more irregular shape. Palladium was loaded on the surface of obtained supports by the impregnation method from the acetone solution of palladium acetylacetonate. Thermogravimetric studies indicated that palladium precursor loaded on CTAB-modified ZnO support was less stable and simultaneously decomposed in broader range of temperatures. Slight differences between the forms of precursors adsorbed on the supports were demonstrated by the diffuse reflectance infrared Fourier transform spectroscopy studies. Thermal decomposition of palladium acetylacetonate precursors in the air led to the formation of PdO species. The influence of ZnO morphology on the metal-oxygen bonds strength in PdO and formation of active phases were observed. Strongly dispersed PdZn crystallites on ZnO supports were formed upon reduction at 350°C. Smaller crystallites of the size equal to 6.5 nm were detected in the Pd/ZnO-AOT catalysts.

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Formation and Characterization of PdZn Alloy: A Very Selective Catalyst for Alkyne Semihydrogenation

Cited by 157 publications

References 54 publications

The Reduction of Alkynes Over Pd-Based Catalyst Materials - A Pathway to Chemical Synthesis

The Reduction of Alkynes Over Pd-Based Catalyst Materials - A Pathway to Chemical Synthesis

Process Intensification of Alkynol Semihydrogenation in a Tube Reactor Coated with a Pd/ZnO Catalyst

Application of microemulsion method for development of methanol steam reforming Pd/ZnO catalysts

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