Optimized palladium catalyst systems for the selective liquid-phase hydrogenation of functionalyzed alkynes

Nijhuis, T.A.; Koten, Gerard van; Moulijn, Jacob A.

doi:10.1016/s0926-860x(02)00372-1

Cited by 78 publications

(74 citation statements)

References 16 publications

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“…As previously mentioned the Lindlar catalyst contains electrondeficient palladium species. Nijhuis et al 41 have found that palladium modified with Pb(OAc) 2 during the Lindlar catalyst preparation gets electron deficient and that this electron deficiency enhances the Pd-alkyne interaction. It should be also considered that 1-heptene is adsorbed more weakly than 1-heptyne on these species.…”

Section: Resultsmentioning

confidence: 99%

Influence of ni addition to a low-loaded palladium catalyst on the selective hydrogenation of 1-heptyne

et al. 2010

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Recebido em 27/4/09; aceito em 30/10/09; publicado na web em 12/3/10 Semi-hydrogenation of alkynes has industrial and academic relevance on a large scale. To increase the activity, selectivity and lifetime of monometallic catalysts, the development of bimetallic catalysts has been investigated. 1-Heptyne hydrogenation over low-loaded Pd and Ni monometallic and PdNi bimetallic catalysts was studied in liquid phase at mild conditions. XPS results suggest that nickel addition to Pd modifies the electronic state of palladium as nickel loading is increased. Low-loaded Pd catalysts showed the highest selectivities (> 95%). The most active prepared catalyst, PdNi (1%) , was more selective than the Lindlar catalyst.

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Section: Resultsmentioning

confidence: 99%

Influence of ni addition to a low-loaded palladium catalyst on the selective hydrogenation of 1-heptyne

et al. 2010

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“…The catalyst was stored in a nitrogen atmosphere. The detailed recipe for this preparation can be found in [4]. Hydrogenation experiments were performed in glass slurry-reactor at 298 K and 1 bar pressure with (dry) ethanol as solvent.…”

Section: Methodsmentioning

confidence: 99%

Separation of kinetics and mass-transport effects for a fast reaction: the selective hydrogenation of functionalized alkynes

et al. 2003

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A kinetic study has been made into the hydrogenation of 3-methyl-1-pentyn-3-ol over palladium on silica catalysts. This reaction already proceeds at very high rates under mild reaction conditions and, therefore, mass-transfer inside the catalyst particle inevitably influences the reaction progress, making the determination of the reaction kinetics difficult. To be able to determine the reaction mechanism and the kinetic parameters, a model has been drawn up in which both mass-transfer and kinetics are modeled simultaneously. This model is able to accurately describe the reaction progress. The model can also be used to explain the effect of commonly used reaction modifiers like quinoline on the reaction. Quinoline can be added to increase the selectivity to the desired alkene intermediate. From the calculations it is shown that the primary function of this type of modifier is to decrease the reaction rate. The lower reaction rate and thereby relatively smaller mass-transfer resistance in the catalyst is most likely a primary cause for the increased selectivity when a reaction modifier is used.

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“…The decrease in the selectivity at a higher pressure might be ascribed either to (i) the mass transfer limitations or (ii) an increased MBY to MBA reaction rate, which is proportional to squared hydrogen pressure. The mass transfer limitations may lead to a slow removal of MBE molecules from the catalyst vicinity, and result in overhydrogenation [29]. There are three possible mechanisms for the masstransfer limited operation: external mass transfer, gas-liquid mass transfer, or internal diffusion in the catalyst.…”

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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Optimized palladium catalyst systems for the selective liquid-phase hydrogenation of functionalyzed alkynes

Cited by 78 publications

References 16 publications

Influence of ni addition to a low-loaded palladium catalyst on the selective hydrogenation of 1-heptyne

Influence of ni addition to a low-loaded palladium catalyst on the selective hydrogenation of 1-heptyne

Separation of kinetics and mass-transport effects for a fast reaction: the selective hydrogenation of functionalized alkynes

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

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