Hydrogenation Of Sunflower Oil Research Articles

Selective hydrogenation of sunflower oil over Ni catalysts

This work focuses on the influence of the support and the preparation method on the activity and selectivity of nickel catalysts in the hydrogenation of sunflower oil. Catalysts were prepared over silica and alumina supports following the incipient wetness impregnation and deposition-precipitation techniques. The activation process was followed by temperature-programmed reduction (TPR). Precipitation-deposition method allowed a stronger metal-support interaction than incipient wetness impregnation. A precipitation-deposition time of 14 h (which allowed a Ni loading of about 20wt%) was deemed as the most adequate from the standpoint of high specific surface area and strong Ni-support interaction. The selectivity to oleic acid was not affected by the preparation method, but it was significantly influenced by the type of support. In this regard, the catalysts prepared on silica are more active and produce less saturated fatty acids.

Influence of Ni/SiO2 activity on the reaction pathway in sunflower oil hydrogenation

Sunflower oil hydrogenation process was studied on silica supported nickel catalysts. Three texturally different silica gel materials were used as supports for synthesis of Ni/SiO2 catalyst precursors. After precursors’ reduction and paraffin oil impregnation, obtained catalysts were used in sunflower oil hydrogenation reaction. For catalytic test, a new type of catalyst feeder was constructed and presented. The hydrogenation activity of catalysts was monitored through the decrease of refractive index and hydrogen consumption. A correlation between iodine value, refractive index and hydrogen consumption was established. The reaction rate constants were obtained from fatty acid composition of partially hydrogenated oil and further studied for the investigation of possible reaction pathways. Kinetics and mechanisms were evaluated and tested with the aim to reduce the number of reactions participating in the reaction scheme. A set of ordinary differential equations, corresponding to the investigated model, was solved numerically by Gear's algorithm. It was shown that a number of significant reactions in a model depend on the activity of catalysts. More active catalyst results in more reaction pathways and more side chemical reactions.

Experimental study of the deactivation of Pd on anodized aluminum monoliths during the partial hydrogenation of vegetable oil

Partial hydrogenation of sunflower oil was studied over Pd/Al2O3/Al catalysts in a monolithic stirred reactor. The catalyst showed similar or even better activity and selectivity than conventional Pd/Al2O3 catalysts. However, in consecutive runs, a continuous decreasing activity was observed. In order to understand the deactivation phenomena, fresh and spent catalysts were characterized using temperature programmed reduction, N2 adsorption isotherms, dynamic H2 chemisorption, transmission electron microscopy (TEM), atomic absorption spectroscopy, inductively coupled plasma spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, ultrasound adherence tests, and X-ray photoelectron spectroscopy. Furthermore, an extensive number of catalytic tests under different operating conditions were carried out. The loss in activity was proportional to the reduction in metal dispersion. The decrease in Pd dispersion was due to the coverage of the Pd surface. The deactivation occurred due to fouling with reaction residues most probably coming from polymerization and/or cross-linking reactions. The catalysts can be regenerated ex situ using a careful desorption–washing–calcination process, although this requires further research because the temperatures required are too high for Al.

Performance of Pd-B/SiO2 Catalyst in Hydrogenation of Sunflower Oil

Performance of Pd-B/SiO2 Catalyst in Hydrogenation of Sunflower Oil

Effect of Catalyst Preparation on the Selective Hydrogenation of Vegetable Oil Over Low Percentage Pd/Diatomite Catalysts

Hydrogenated vegetable oils contain high contents of <em>trans</em>-fatty acids. Because of the increased health concern about <em>trans</em>-fatty acids, new hydrogenations have been studied to seek ways for substantial reduction of the <em>trans</em>-fatty acids in the hydrogenated products. In this research, activated diatomite has distinctive properties as a support for hydrogenation catalysts. Investigation of textural properties of raw and purified diatomite samples reveals that during acid activation surface area increases significantly. Although, acid activation of diatomite is a commonly chemical modification to enhance its adsorption capacity. We are preparing adsorption method to synthesize low percentage 0.2% of Pd/Diatomite catalyst. The activated diatomite and the obtained catalyst was characterized by using thermogravimetric analysis (TGA), Brunauer-Emmett-Teller surface area analysis (BET), scanning electron microscopy (SEMEDAX), transmission electron microscopy (TEM). It was utilized for hydrogenation of sunflower oil using the Parr reactor in laboratory testing a variety of temperature (70, 90, 110 ºC) and canola oil in industrial testing, at temperature 90 ºC and 0.5 MPa pressure and compared to commercial nickel catalyst (Pricat-9910) at 150 ºC, 0.5 MPa pressure agitation of 800 rpm for 160 min. The changes in iodine value, fatty acid composition, <em>trans</em>-fatty acids, melting point and solid fat content were investigated on partial hydrogenated sunflower oil and canola oil. The experimentally obtained results show that the palladium catalyst is the most active compared to the commercial catalyst. Lower hydrogenation temperature used 0.2% Pd/Diatomite catalyst, significant reducing the formation of <em>trans</em>-content by 13% in fat.

Development of palladium catalysts on carbon supports from the Sibunit family for vegetable oil hydrogenation processes

Studies on the synthesis of powdered Pd/C catalysts prepared by the supporting of Pd onto a mesoporous carbon material from the Sibunit family and the characterization of their properties in the process of the partial hydrogenation of sunflower oil are reported. The comparative tests of a 1.0 wt % Pd/Sibunit catalyst and Pricat and Nysosel commercial nickel catalysts in the hydrogenation sunflower oil were performed with the use of a Parr batch reactor. It was found that the Pd catalyst was superior to Ni analogs in activity, and it afforded sunflower oil partial hydrogenation products with reproducible characteristics.

Hydrogenation of sunflower oil over Pt–Ni bimetallic supported catalysts: Preparation, characterization and catalytic activity

It has been reported that in order to improve sunflower oil hydrogenation catalysts the geometric or electronic effects of the catalysts must be manipulated in order to achieve the desired activity or selectivity. To achieve this, the development of an active and selective bimetallic catalyst was undertaken. An innovative approach was taken to synthesize Pt–Ni catalysts supported on mesoporous silica using the surface redox reaction (Srr) technique. It was determined that the Srr preparation method resulted in better activity and lower selectivity towards trans isomer than the traditional successive and co-impregnation bimetallic impregnation techniques. The change in selectivity can be explained by a promoter electronic effect generated by the close proximity of a second metal on the catalysts surface and from a geometric effect due to the incorporation of the Ni on the surface. All the bimetallic catalysts showed a drop in the formation of trans compared to the monometallic catalyst.

Effect of chemically reduced palladium supported catalyst on sunflower oil hydrogenation conversion and selectivity

Catalytic hydrogenation of sunflower oil was studied in order to improve the conversion and to reduce the trans-isomerization selectivity. The hydrogenation was performed using Pd–B/γ-Al2O3 prepared catalyst and Pd/Al2O3 commercial catalyst under similar conditions. The Pd–B/γ-Al2O3 catalyst was prepared by wet impregnation and chemical reduction processes. It was characterized by Brunauer–Emmett–Teller surface area analysis (BET), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The result of sunflower oil hydrogenation on Pd–B/γ-Al2O3 catalyst showed a 17% higher conversion and a 23% lower trans-isomerization selectivity compared to the commercial Pd/Al2O3 catalyst. The chemical reduction of palladium supported catalyst using potassium borohydride (KBH4) has affected the Pd–B/γ-Al2O3 catalyst’s structure and particle size. These most likely influenced its catalytic performance toward higher conversion and lower trans-isomerization selectivity.

Thermally Activated Palm Kernel Based Carbon as a Support for Edible Oil Hydrogenation Catalyst

Activated carbon has distinctive properties as a support for hydrogenation catalysts. Thermally activated carbon has been prepared from palm kernel shell at 1073 K and placed under nitrogen flow for 2 h. It was impregnated by palladium using toluene solution of Pd (acac)2. The Pd/C was reduced using a water solution of potassium borohydride (KBH4). The Pd-B/C was characterized by the Brunauer-Emmett-Teller surface area analysis (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and inductively-coupled plasma mass spectrometry (ICP-MS). Pd-B/C was applied for sunflower oil hydrogenation at a temperature of 373 K, hydrogen pressure of 413.5 kPa and agitation of 1400 rpm for 1 h. Pd-B/C noticeably exhibited a higher overall catalyst activity in comparison to some recently published palladium catalysts.

Monolithic Stirrer Reactor: Performance in the Partial Hydrogenation of Sunflower Oil

In the present paper, the performance of monolithic catalysts obtained from a catalytic converter was analyzed in the partial hydrogenation of sunflower oil. The monoliths were reimpregnated with palladium and installed as a blade in a monolithic stirrer reactor. The use of this type of reactor was explored in the reaction at 373 K and 413 kPa, analyzing the effect variables such as stirrer speed, hydrogen supply, and stirrer design on the catalyst activity and selectivity to trans-isomers and saturated product. The volumetric gas–liquid and liquid–solid mass transfer coefficients were calculated, and the influence of the stirrer speed was examined. Estimations of the Carberry numbers and Weisz–Prater modulus were used for establishing the presence or absence of mass transfer resistances. The performance of the catalyst was studied in consecutive tests, and different procedures for catalyst regeneration were applied.

Partial hydrogenation of sunflower oil: Influence of the process conditions on the physicochemical properties of the products

The influence of the process conditions on the fatty acid composition and solid fat content of the products was examined for partial hydrogenation of sunflower oil in a static reactor using 1.0 wt% Pd/C powder catalyst. The solid fat content curves of the oil hydrogenation products were analyzed in relation to the process conditions.

Selective hydrogenation of sunflower oil over noble metal catalysts

Selective hydrogenation of sunflower oil was tested using a variety of heterogeneous catalysts. The reaction was carried out in a batch reactor under different operating conditions. Palladium and platinum supported on Al 2O 3, ZrO 2 and TiO 2 were screened. A range of metal dispersions (6–69%) and loadings (0.3–3.9%) were studied for promotion of selectivity in cis C 18:1. The catalysts were compared with a conventional Ni catalyst. The Pd catalysts were found to be much more active than the Ni catalyst. The Pt catalyst, while not as active as the Pd catalysts, produced lower trans fatty acids during hydrogenation. The level of trans could be further reduced by increasing the operating pressure to 10 bar and reducing the reaction temperature to 100 °C. The reduction in trans formation was most significant for the Pt based catalyst. The different catalysts prepared were shown to process a wide variety of different characteristics in terms of metal dispersion, surface areas, particle size, etc. However, this had little influence on the overall activity of the samples. The key issue in terms of activity was the catalyst metal content.

Palladium catalyst on anodized aluminum monoliths for the partial hydrogenation of vegetable oil

The present work explores the viability of introducing improvements to the conventional process of hydrogenation using structured catalysts. Monolithic catalysts of anodized aluminum were prepared and characterized. They were impregnated with palladium and used as monolithic stirrers in the sunflower oil hydrogenation reaction at 100 °C and 413 kPa. The monolithic catalysts showed to be active, with a 50% C C conversion in 30 min. When consecutive tests were performed, a loss of activity was observed, decreasing 80% in the sixth test, which is attributed to the presence of carbonaceous residues.

An alternative process for hydrogenation of sunflower oil

Classic methodologies for hydrogenation of vegetable oils have traditionally been carried out by nickel catalysts under high pressure of H2 and high temperature. An alternative method for hydrogenation of sunflower oil using limonene and palladium-on-carbon was investigated in this study. The use of limonene as a hydrogen donor solvent was proposed in order to avoid high temperature and high-pressure conditions. The catalytic transfer of hydrogenation was studied by using 0.5 to 2% of Pd as a catalyst, a limonene:oil ratio of 3:1, and reaction times from 0.5 to 2 hours. Under these conditions, high selectivities for oleic acid and low concentrations of stearic acid were obtained.

Hydrogenation of sunflower oil over platinum supported on silica catalysts: Preparation, characterisation and catalytic activity

The effect of varying the Pt content (0.7 - 4.6 wt %) over a novel mesoporous SiO 2 support was investigated for hydrogenation of sunflower oil. The reaction was carried out in a batch reactor at 170 °C, 400 rpm and 3 bar hydrogen pressure. The activity and selectivity of the different catalysts to trans fatty acid formation were compared. The choice of metal precursor affected the catalyst activity, H 2PtCl 6 showed a moderate increase of the Pt activity compared to Pt(AcAc) 2. The presence of chlorine on a supported catalyst is believed to give rise to improved hydrogen spillover, which in turn may improve the hydrogenation activity. For the catalysts prepared using Pt(AcAc) 2, the activity improved with increased Pt loading up to 1.5%Pt, above which no significant increase in activity was observed with additional Pt loading. Additionally, it was found that the activity per exposed metal was greater at lower Pt loadings. The amount of Pt supported on the silica was shown to influence the selectivity to trans C18:1. Increasing the Pt loading from 0.7% to 4.6% correspondingly decreased the metal dispersion and increased the metal particle size. The smaller particles on the 0.7%Pt/SiO 2, 1.5%Pt/SiO 2 and the 2.7%Pt/SiO 2 catalysts presented a lower trans content compared to the 4.6%Pt/SiO 2 catalyst that exhibited larger particles.

Catalytic Hydrogenations in Microemulsion Systems with Rh-TPPTS: Partial Hydrogenation of Sunflower Oil

The effect of the P/Rh ratio and the surfactant concentration on the partial hydrogenation of sunflower oil in Triton X-100 microemulsion systems with the water-soluble catalyst complex Rh-TPPTS has been studied. An unusual hindering effect of the surfactant on the production of elaidic acid and stearic acid as the oil is hydrogenated was observed. When increasing the concentration of Triton X-100 in the reaction medium from 3 to 15 wt%, the content of elaidic acid and stearic acid were lowered 21 and 34%, respectively. The maximum content of oleic acid was attained when the concentration of Triton X-100 was 15 wt%, obtaining a high content of 51.8% of oleic acid. When the ligand/metal ratio was higher, the reaction was slower but more selective to oleic acid. The Rh-TPPTS catalyst could be recycled up to 3 times after hydrogenation of sunflower oil by extracting the oil phase of a three-phase microemulsion system, observing a continuous deactivation of the catalyst.

Hydrogenation of sunflower oil over different palladium supported catalysts: Activity and selectivity

Six palladium catalysts were prepared using different precursors (palladium acetylacetonate, palladium nitrate and tetraamminepalladium nitrate) and supports (α-Al 2O 3, γ-Al 2O 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. Pd catalysts showed a higher activity, similar trans-isomer formation, and were more selective towards monoene formation than Ni catalysts. On the other hand, under the studied operating conditions, the different supports did not improve significantly the selectivity or the activity of the reaction. The γ-alumina supported Pd catalyst, with a metal loading of 0.78 wt% and a 60% dispersion, showed a specific activity higher than the other Pd catalysts. For the same double bond conversion, this sample originated a slightly lower amount of total trans-isomers than the Ni catalyst, but it produced less saturated compound and was more selective towards monounsaturated fatty acid formation.

Pd/Al2O3-cordierite and Pd/Al2O3-Fecralloy monolithic catalysts for the hydrogenation of sunflower oil

Abstract Monolithic catalysts were prepared using cordierite and Fecralloy as substrates, with Pd/Al 2 O 3 catalyst deposited by a washcoating method. The samples were characterized and studied for the partial hydrogenation of sunflower oil at 373 K and 413 kPa. In comparative tests, at equal operating conditions and conversion, the structured catalysts presented a lower trans -isomers formation than the powder catalyst. After three consecutive tests, the ceramic monolith showed no change in activity or selectivity, whereas the metallic monolith showed a partial deactivation (10%), which is attributed to a loss of catalyst.

Partial hydrogenation of sunflower oil: Use of edible modifiers of the cis/ trans-selectivity

The partial hydrogenation of sunflower oil with minimum trans-isomer formation is studied, using a Pd/γ-alumina catalyst modified with promoters apt for human consumption: ethyl benzoate and magnesium glycinate. It was found that the hydrogenation rate diminishes with the additions of the modifiers. Regarding the cis/ trans-selectivity, significant differences were found: ethyl benzoate promoted the formation of trans-isomers, whereas magnesium glycinate diminished it. The results can be interpreted in terms of different effects: change in the electron density of palladium, which affects the relative adsorption strength of the reactant, intermediates and hydrogen, and a block of part of the surface by the modifiers. Theoretical calculations were performed to support this hypothesis.

Effect of reactor type on trans fatty acid and stearate formation in fat hydrogenation in SCF solvent

Hydrogenation of vegetable fats is an important biomolecule modification process, traditionally carried out in a slurry reactor at low pressure (2–6 bar). Here, the hydrogenation of sunflower oil in supercritical propane and dimethyl ether catalysed by Pd (supported on activated carbon or alumina) is studied. One-dimensional simulation models for plug flow and mixed flow reactors, as well as two-dimensional dispersed plug flow reactor models, were developed for the case of isothermal and adiabatic operation. The hydrogenation of sunflower oil is considered as a reaction network based on linoleate, oleate ( cis C18:1), elaidate ( trans C18:1) and stearate triesters. Since trans fatty C18:1 ester and stearate formation is not desired, the question arises as to which reactor type is best to achieve a low elaidate content. Depending on the final allowed stearate content, different mixed and plug flow reactor models can be applied. However, for a fixed stearate formation rate, the mixed reactor gives a lower trans content than the plug flow reactor in most cases. Also, low temperature operation results in better oleate/stearate selectivity. Two-dimensional tubular reactor dispersed simulation does not give further insight into the problem. The use of Multiphysics (finite element method) for solving the dispersed plug flow model provides a way to simulate CSTR reactor behaviour. In our case, both heat and mass Péclet numbers of 10 −4 or less are sufficient to describe well-mixed reactor behaviour using the 2D mass and heat transfer pseudo-homogeneous model with radial and axial effects, with parameter values available for SCF. The models can be used for planning reaction operations in SCF as solvents intended for low trans fatty acid.