Sunflower oil hydrogenation on Pt catalysts: Comparison between conventional process and homogeneous phase operation using supercritical propane (original) (raw)
Related papers
Chemical Engineering Journal, 2009
Six palladium catalysts were prepared using different precursors (palladium acetylacetonate, palladium nitrate and tetraamminepalladium nitrate) and supports (␣-Al 2 O 3 , ␥-Al 2 O 3 , ZSM-5, and MCM-22). The samples were characterized by atomic absorption spectroscopy, N 2 adsorption isotherms, XRD, H 2 chemisorption, transmission electron microscopy and temperature programmed reduction. The activity and selectivity of the catalysts were investigated in the hydrogenation of sunflower oil and compared to a commercial Ni catalyst.
Vegetable Oil Hydrogenation over Pt Monolithic and Powder Catalysts: Experimental and Modeling Study
Chemical Engineering & Technology
A complete kinetic study was performed for the hydrogenation of vegetable oil using a powder and a monolithic Pt catalyst. The experimental studies were carried out at a wide interval of H 2 pressure, temperature, and catalyst loading using Pt/g-Al 2 O 3 powder catalyst in a slurry reactor and Pt/Al 2 O 3 /Al-structured catalyst in a monolithic stirrer reactor. The mathematical model for the reactors includes the hydrogenation and isomerization reactions, the external gas-liquid and liquidsolid mass transfer as well as the internal mass transfer. Four kinetic models were evaluated for both catalysts. The best fit of the experimental data was obtained by adopting a Langmuir-Hinshelwood kinetic model for the liquid reactant and a dissociative adsorption and zero-order reaction for H 2 .
Palladium supported catalysts for the selective hydrogenation of sunflower oil
Journal of Molecular Catalysis A: Chemical, 2005
Selective hydrogenation of ethyl esters of traditional sunflower oil (SOEE) was carried out at low temperature (40 • C) in ethanol as solvent in the presence of supported palladium catalysts. In the range of studied dispersions (12-55%), the SOEE hydrogenation reaction is insensitive to the size of the palladium particles deposited on silica, but the largest metallic particles enhance the C18:1 cis-trans isomerization. The use of various oxide supports () to deposit palladium does not allow to improve the selectivity of the reaction toward the cis C18:1 compared to Pd/SiO 2 catalysts. On the other hand, the modification of palladium by lead, introduced by surface redox reaction (catalytic reduction), promotes the selectivity in cis C18:1. In addition, this technique of preparation involves a moderate decrease of the palladium activity compared to a traditional method of successive impregnations. The introduction of amines in the reaction medium modifies the hydrogenating properties of the Pd/SiO 2 catalyst. According to the quantity and the nature of the added amine (aliphatic with linear or ramified chain and cyclic compounds), the catalytic activity can either be unchanged or inhibited. These evolutions result from a promoter electronic effect generated by the presence of the amine and from a poison geometric effect related to the adsorption of this nitrogencontaining compound on the palladium surface. Whatever the nature of the amine, it induces an increase of the selectivity toward the cis C18:1.
Kinetics of the Hydrogenation of Sunflower Oil over Alumina Supported Palladium Catalyst
International Journal of Chemical Reactor Engineering, 2000
The present work studies the sunflower oil hydrogenation on supported palladium catalysts, by analyzing the surface kinetics and the mass transfer limitations of products and reactants. Initially, a simplified model was studied. This model took into account only the consecutive hydrogenation of linoleic acid (diene), to reach the production of oleic (monoene) and stearic (saturated) acids. Using the adjusted values of the kinetic constants and the activation energies of the hydrogenation obtained with this model, a new scheme was investigated considering the geometric isomerization reactions (cis-trans). The diene hydrogenation constant was larger than that of the monoene. This fact confirms the higher reaction rate of the diene hydrogenation in comparison with that of the monoene. With respect to the isomerization rates, these have an activation energy superior to that of the monoene hydrogenation, and slightly superior to the diene hydrogenation activation energy. This fact verifies the influence of temperature on the formation of trans-isomers.
Revisiting the hydrogenation of sunflower oil over a Ni catalyst
Journal of Food Engineering, 2007
In the present paper the performance of commercial Ni catalyst in edible oil hydrogenation is evaluated under different operating conditions. Particularly, the influence of mass transport resistance on the trans-isomers selectivity is analyzed. Initially a series of experiments aim to analyze the effect of four process variables (reaction temperature, hydrogen bubbling device, agitation rate and stirrer design) on catalyst activity and selectivity to trans-isomers. These experiments are conducted in diffusional regimes. A simpler set of experiments is carried out operating under conditions that allow the authors to neglect some diffusional resistances although those associated to the catalyst are still present. In the first case activity and selectivity appear to be independent of the hydrogen bubbling system and the catalyst loading. The whole set of data analyzed in terms of the C18:1/C18:2 0 ratio as a function of the C18:2/C18:2 0 ratio shows that the former, a sort of selectivity, depends on the agitation regime. The formation of trans-isomers however, appears to be a function of the reaction extent only.
Topics in Catalysis, 2006
Hydrogenation of sunflower and canola oils over a novel Pd-supported catalyst (pore size of 6.8 nm and BET specific surface area of 837 m 2 /g) was investigated and compared to commercial nickel catalyst. The formulated catalyst with Pd-loading of 1 wt%, supported on structured silica material was active and selective for the hydrogenation of sunflower and canola oils under mild process conditions. For both oils, the novel Pd supported catalyst exhibited a better selectivity than commercial Ni catalyst at a similar activity with a lower metal loading. For the same iodine value (IV) reduction, the Pd-catalyst produced less saturated fatty acids (SFA) and about the same level of trans fatty acids (TFA), but was more selective towards cis monoenes formation than Ni-catalyst. More importantly, this catalyst produced a reduced level of stearic acid, which at increased levels causes waxy mouth feel of the hydrogenated fat.
Sunflower oil hydrogenation mechanisms and kinetics
Chemical Engineering Journal, 2021
A kinetic model for sunflower oil hydrogenation on a palladium catalyst is proposed based on Horiuty-Polanyi type mechanism and considering either a dissociative or associative adsorption of hydrogen. The derived kinetic laws allow to explain the distinct dependency of saturation and isomerization reactions on hydrogen pressure. Kinetic parameters are identified based on batch slurry hydrogenations carried out at 60-160 • C and 2-31 bar with a powdered Pd/Al 2 O 3 catalyst. A statistical analysis is used to select the most suitable adsorption mechanism for H 2. Evaluation of the Weisz-Prater modulus reveals that limitations to intraparticle diffusion occur despite the particle diameter does not exceed 40 μm.