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Journal ArticleDOI

Kinetics, Gas−Liquid Mass Transfer, and Modeling of the Soybean Oil Hydrogenation Process

22 Jan 2002-Industrial & Engineering Chemistry Research (American Chemical Society)-Vol. 41, Iss: 4, pp 697-709
TL;DR: In this paper, the kinetics for soybean oil hydrogenation using a commercial Ni/Al2O3 catalyst were investigated in a 2 × 10-3 m3 agitated reaction calorimeter operating under a wide range of temperatures.
Abstract: The kinetics for soybean oil hydrogenation using a commercial Ni/Al2O3 catalyst were investigated in a 2 × 10-3 m3 agitated reaction calorimeter operating under a wide range of temperatures (383−44...
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors studied the catalytic hydrogenation of d-glucose to d-sorbitol over a 5% Ru/C catalyst in a semi-batch slurry autoclave operating at 373-403 K and 4.0-7.5 MPa hydrogen pressure.
Abstract: The catalytic hydrogenation of d -glucose to d -sorbitol over a 5% Ru/C catalyst was studied in a semi-batch slurry autoclave operating at 373–403 K and 4.0–7.5 MPa hydrogen pressure. The d -glucose concentration was varied between 0.56 and 1.39 mol/l. The kinetic experiments were carried out in the absence of mass transport limitations, which was verified by using measured gas–liquid mass transfer coefficients and estimated diffusion and liquid–solid mass transfer coefficients. Many literature reports suffer from transport limitations. In the operating regime studied the reaction rate showed a first order dependency with respect to hydrogen. A shift in the order of d -glucose was observed. At low d -glucose concentrations (up to ca. 0.3 mol/l) the reaction showed a first order dependency, while at higher concentrations this changed to zero order behavior. No inhibition by sorbitol or mannitol was observed. The kinetic data were modeled using three plausible rate models based on Langmuir–Hinshelwood–Hougen–Watson (LHHW) kinetics assuming that the surface reaction is rate-determining. Model 1 involves non-competitive adsorption of hydrogen and d -glucose. Hydrogen adsorption is either molecular or dissociative, but due to the weak adsorption it results in both cases in a linear hydrogen pressure dependency, i.e. the same rate expression; Model 2 is based on competitive adsorption of molecular hydrogen and d -glucose; and Model 3 assumes competitive adsorption of dissociatively chemisorbed hydrogen and d -glucose. All three models described the data satisfactorily and further statistic discrimination between these models was not possible.

164 citations

Journal ArticleDOI
TL;DR: The most important reaction calorimetric principles (heat-flow, heat-balance, power-compensation, and Peltier principle) and their applications in commercial or scientific devices are reviewed in this article.

87 citations

Journal ArticleDOI
TL;DR: The use of monolithic catalysts in multiphase applications has received increasing interest throughout the last years as discussed by the authors, and it is also demonstrated that the monolithic catalyst could be reused several times without significant changes in the product composition.
Abstract: The use of monolithic catalysts in multiphase applications has received increasing interest throughout the last years. In this paper the use of monolithic catalysts in the hydrogenation of edible oils is studied. In comparative experiments the monolithic catalysts have shown a lower tendency to form trans-fatty acids compared to slurry catalysts with equal composition. It is also demonstrated that the monolithic catalyst could be reused several times without significant changes in the product composition. With respect to the effect of the operating parameters on the performance, common knowledge applies. By using a monolithic-catalyst-based technology, the process complexity can be significantly reduced as the separation of the oil and the catalyst becomes straightforward and the filtration and bleach steps are eliminated. An economic evaluation showed a significant reduction in the product cost when monoliths are used instead of a conventional slurry system.

65 citations

Patent
30 Jul 2004
TL;DR: In this paper, the authors present low trans-fatty acid fat compositions, methods of hydrogenating unsaturated feedstocks (e.g., oils), and hydrogenation catalyst compositions.
Abstract: The present disclosure provides low trans-fatty acid fat compositions, methods of hydrogenating unsaturated feedstocks (e.g., oils), and hydrogenation catalyst compositions. One exemplary method involves producing a catalyst composition by heating a nickel-based catalyst to a first temperature of at least about 85° C in the presence of hydrogen and a fat component. An unsaturated feedstock may be contacted with the catalyst composition and hydrogenated by sustaining a hydrogenation reaction at a second temperature of no greater than about 700 C. Some specific implementations of the invention permit the production of partially hydrogenated seed oils with low trans-fatty acid contents.

50 citations

Journal ArticleDOI
TL;DR: In this paper, the authors summarized recent developments in hydrogenation of CC and CO in FAMEs with focus on catalysts, reaction mechanisms, and reactor conditions, and the opportunities for future research in the field are outlined.

48 citations

References
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Journal ArticleDOI
TL;DR: In this article, the authors investigated gas liquid mass transfer in gas induced stirred reactors by the method of physical absorption, based on pressure variation, using two different gas-inducers, liquid composition temperature and height in the reactor, gas pressure and type, solid catalyst type and concentration have been varied in a lab reactor.

85 citations

Journal ArticleDOI
TL;DR: In this paper, experimental data on the volumetric gas−liquid mass transfer coefficient (kLa), liquid-side mass transfer coefficients (kL), gas-liquid interfacial area (a), bubble Sauter m...
Abstract: This paper presents some experimental data on the volumetric gas−liquid mass-transfer coefficient (kLa), liquid-side mass-transfer coefficient (kL), gas−liquid interfacial area (a), bubble Sauter m...

53 citations

Journal ArticleDOI
TL;DR: In this paper, the contribution of mass transfer to the reaction rates was carefully evaluated by determining the mass transfer parameters according to independent routes, and a more general kinetic model was developed based on a complex scheme of simultaneous and consecutive reactions where hydrogenation reactions occur together with cis-trans isomerizations.
Abstract: The partial hydrogenation of a rapeseed oil in the presence of a supported palladium catalyst was studied. In the temperature range 60–120°C, at which kinetic data were collected, we observed that diffusion limitations are always operative, in particular intraparticle diffusion limitations. The contribution of the mass transfer to the reaction rates was carefully evaluated by determining the mass transfer parameters according to independent routes. In spite of the masking effect of diffusion, kinetic laws suitable to describe the hydrogenation of trienic, dienic and monoenic compounds were identified. A Langmuir-Hinshelwood kinetic equation describes well the behaviour of the unsaturated molecules in the reaction, while the hydrogen reaction order was indirectly shown to be zero. A 3/2/1 ratio between the adsorption constants of trienic, dienic and monoenic compounds was assumed, corresponding to the different probability of a double bond interaction with the palladium surface. The kinetic constants obtained by fitting experimental data gave quite similar results for the polyunsaturated fatty acids and very different for the monounsaturated ones, revealing an intervention of two distinct reaction mechanisms. In the case of polyunsaturated fatty acids, double bond migration with the formation of conjugated dienes would occur before hydrogenation. Conjugated dienes are more quickly hydrogenated than isolated or single double bonds. In a second part of the paper, a more general kinetic model is developed based on a complex scheme of simultaneous and consecutive reactions where hydrogenation reactions occur together with cis-trans isomerizations. A kinetic equation with the corresponding parameters for the cis-trans isomerization of the C 18 monoenic species was determined from experimental data. Subsequently, this equation was used with the same parameters in the general kinetic model to describe the behaviour of all the other cis-trans isomerization reactions. This assumption has turned out to be reasonable. The reliability of the more general kinetic model, of the mass transfer and kinetic equations for hydrogenation processes, of the kinetic equation for cis-trans isomerizations, and of the parameters appearing in the model was verified on the basis of all the experimental data collected. A brief discussion on the factors influencing the catalyst selectivity concludes the paper.

44 citations

Journal ArticleDOI
TL;DR: In this paper, a dissolution technique was used to measure the solid-liquid mass transfer coefficient in gas-solid-liquid vessels stirred by either radial or axial impellers, and the mechanical power dissipated by the stirrers at various agitation speeds and gas flow rates was also measured by means of a new technique.
Abstract: The research on mass transfer coefficients in solid-liquid agitated systems has received substantial attention in the past, due both to the interest in fundamental aspects of mass transfer between particles and turbulent fluids and to the importance of practical applications. In contrast, little information is available on solid-liquid mass transfer when a third gaseous phase is also dispersed into the system, in spite of the importance of the applications of gas-solid-liquid agitated systems. In this work a suitable dissolution technique was used to measure the solid-liquid mass transfer coefficient in gas-solid-liquid vessels stirred by either radial or axial impellers. The mechanical power dissipated by the stirrers at various agitation speeds and gas flow rates was also measured by means of a new technique. The mass transfer data obtained were found to be well correlated to the 0.25 power of the specific power dissipation, indicating that the Kolmogorov's theory of mass transfer applies to these systems, while no clear influence of the gas hold-up was ascertained.

43 citations