Vapor-phase hydrogenation of acetone on applied metals of the platinum group

Pavlenko, N. V.; Tripol’skii, A. I.; Голодец, Г. И.

doi:10.1007/bf00524061

Cited by 5 publications

(6 citation statements)

References 2 publications

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“…As illustrated in Fig. 3, the apparent barrier for hydrogenation is approximately 50 kJ mol -1 for all C 3 -C 5 ketones in the range of 303-359 K, which is consistent with previously reported apparent barriers for acetone hydrogenation over supported group VIII metals [23][24][25]. This suggests that differences in rates observed between acetone, 2-butanone, and 2-pentanone arise from differences in adsorbate surface coverages and/or pre-exponential factors (activation entropies); however, further interpretation is difficult at this stage, and we defer in depth discussion to subsequent microkinetic analysis (Section 4.5).…”

Section: Apparent Kinetics Of Ketone Hydrogenation: Low Temperaturessupporting

confidence: 91%

“…The kinetics of carbonyl hydrogenation are generally interpreted in the context of the Horiuti-Polanyi mechanism, which is predicated on step-wise addition of hydrogen adatoms to an unsaturated, surface-bound hydrocarbon [24,[26][27][28]; however, there remains some uncertainty regarding the site requirements for this process on a given metal surface. In separate studies, hydrogenation kinetics have been reconciled with schemes in which the rate controlling step involves a reaction between a hydrogen atom and a hydrocarbon fragment that are both bound at a single type of active site [24] and schemes in which the rate controlling step involves a reaction between a hydrogen atom and a hydrocarbon fragment that are bound at distinct types of active sites [23,25]. Because neither model can be excluded a priori, we consider both prior to framing a more fundamental analysis.…”

Section: Elementary Surface Stepsmentioning

confidence: 99%

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Microkinetic analysis of C3–C5 ketone hydrogenation over supported Ru catalysts

Abdelrahman

Heyden

Bond

2017

Journal of Catalysis

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Rates of C 3 -C 5 ketone hydrogenation are measured in the vapor phase over Ru/SiO 2 . Reaction kinetics are considered through a range of ketone partial pressures (0.3 -30 Torr), hydrogen partial pressures (90 -900 Torr), and reaction temperatures (322 -456 K). Ketone hydrogenation is observed to be facile, with site time yields ranging from 0.14 s -1 for 2pentanone to 0.37 s -1 for acetone at 322 K and 1.2 bar H 2 . At low temperatures, apparent reaction orders and kinetic barriers are similar for all ketones. During acetone hydrogenation at higher temperatures, (422 K), the ketone order increases from 0 to 0.4, while the hydrogen order increases from 0.5 to 0.9. Furthermore, the apparent barrier decreases from ≈ 50 kJ mol -1 at 322 K to ≈ 18 kJ mol -1 . Apparent trends in hydrogenation rates are interpreted at an elementary level

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Section: Apparent Kinetics Of Ketone Hydrogenation: Low Temperaturessupporting

confidence: 91%

Section: Elementary Surface Stepsmentioning

confidence: 99%

Microkinetic analysis of C3–C5 ketone hydrogenation over supported Ru catalysts

Abdelrahman

Heyden

Bond

2017

Journal of Catalysis

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“…The stages of the mechanism of this process, based on a detailed investigation of the kinetics of this process and adsorption data, include as the limiting step the hydrogenation of adsorbed acetone by adsorbed H atoms [5,6]: The adsorption equilibrium of the starting materials is established in the first two steps. Hydrogen is adsorbed on Z H centers, acetone at Z A centers.…”

mentioning

confidence: 99%

“…Hydrogen is adsorbed on Z H centers, acetone at Z A centers. The kinetics for the formation of the alcohol is described by the following equation [5,6]:…”

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confidence: 99%

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Influence of the fractal nature and dipersity of deposited metal catalysts on the kinetics of the hydrogenation of acetone

Tripol’skii

Strizhak

2007

Theor Exp Chem

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The influence of the morphology of deposited catalysts on some kinetic parameters of a heterogeneous catalytic process has been studied. The interconnection between the pre-exponential factor of the rate constant of the limiting stage of the reaction and the fractal dimension of the distribution of the active component on the surface of the carrier has been established. The relation has been illustrated using the heterogeneous catalytic hydrogenation of acetone to isopropanol on deposited transition metals.The process of a heterogeneous catalytic reaction on the surface of catalysts is caused by the important dependence of the rate of the reaction on the structure (of the catalyst). The morphologies of most catalysts are complex which complicates quantitative estimate of its influence on the kinetics of heterogeneous catalytic reactions. In recent times an approach based on the use of fractal geometry for the quantitative description of the morphology of a catalysts on the kinetics of heterogeneous catalytic processes has been actively developed [1,2]. It has been shown that the rate of a chemical reaction r depends on the dimension of a reagent R according to a power law: r = kR D F [1]. In this equation D F is the fractal dimension in the kinetic field of the process concerned. The influence of the structure of the catalyst on the kinetics of the reaction, complicated by processes of mass transfer inside the grain, is described elsewhere [3].Most catalysts have the active component (most commonly a metal) highly dispersed on an "inert" carrier. The influence of the active component on the rate of the catalytic process is determined by its chemical nature and the particle size. The reactivity of the surface atoms depends on the dispersed state of the active component [4].The present study is connected with the description of the theoretical approach, which permits allowance to be made for the morphology of the catalyst, the quantitative measure of which is the fractal dimension D F , on the kinetic parameters of the process. The validity of the obtained theoretical relationship is illustrated using as an example the kinetics of the heterogeneous catalytic hydrogenation of acetone to isopropanol in the presence of a number of transition metals deposited on aluminum oxide.The kinetic measurements were carried out at atmospheric pressure by a circulating flow method, described in detail elsewhere [5,6]. The constants of the kinetic model were calculated from the experimental results for all the catalysts studied, and also the activation energies and heats of absorption from the temperature dependence of the constants. The values of the specific surface of a metal was calculated from the chemisorption of oxygen in a pulsed chromatographic regime, the average size of the metal particles was calculated from the absorption data, starting from the assumption that they are cubic and that one face is screened by the carrier. The values of the kinetic and physico-chemical parameters of the deposited carriers are given in T...

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Kinetics of acetone hydrogenation for synthesis of isopropyl alcohol over Cu-Al mixed oxide catalysts

Basu

Pradhan

2020

Catalysis Today

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Vapor-phase hydrogenation of acetone on applied metals of the platinum group

Cited by 5 publications

References 2 publications

Microkinetic analysis of C3–C5 ketone hydrogenation over supported Ru catalysts

Microkinetic analysis of C3–C5 ketone hydrogenation over supported Ru catalysts

Influence of the fractal nature and dipersity of deposited metal catalysts on the kinetics of the hydrogenation of acetone

Kinetics of acetone hydrogenation for synthesis of isopropyl alcohol over Cu-Al mixed oxide catalysts

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