Influence of ruthenium precursor on catalytic activity of Ru/Al2O3 catalyst in selective isomerization of linoleic acid to cis-9,trans-11- and trans-10,cis-12-conjugated linoleic acid

Bernas, Andreas; Kumar, Narendra; Laukkanen, P.; Väyrynen, J.; Salmi, Tapio; Murzin, Dmitry Yu.

doi:10.1016/j.apcata.2004.02.032

Cited by 34 publications

(18 citation statements)

References 22 publications

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“…For instance, Iyagba et al [6] and Ragaini et al [8] reported that the presence of chloride decreased significantly the CO hydrogenation activity of silica or alumina supported ruthenium catalyst as a result of a decrease in the number of reactive surface sites. Bernas and coworkers [3] suggested the acidic properties of residual chloride led to the lower selectivity to the desired CLA isomers. As for ammonia synthesis, chlorine suppresses the activity has been observed at ruthenium catalysts with different supports such as MgO, Al 2 O 3 [9,11,17,18].…”

Section: Introductionmentioning

confidence: 98%

“…Oxides supported ruthenium catalysts have been used in various catalytic reactions, such as the hydrogenolysis of paraffins and olefins [1,2], isomerization of linoleic acid [3], selective hydrogenation of benzene [4,5], FischerTropsch synthesis [6][7][8] and ammonia synthesis [9][10][11][12][13][14][15][16][17][18]. Generally, Ru 3 (CO) 12 or other chlorine-free ruthenium compounds rather than the stable and cheap RuCl 3 are employed as ruthenium precursor since the catalytic activity usually significantly decreased due to the presence of chlorine.…”

Section: Introductionmentioning

confidence: 99%

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Physicochemical Characterization and H2-TPD Study of Alumina Supported Ruthenium Catalysts

Lin

Wang

et al. 2008

Catal Lett

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A series of alumina supported ruthenium catalysts, which prepared by hydrogen treatment or hydrazine reduction, were characterized by N 2 adsorption, X-ray diffraction (XRD), X-ray fluorescence (XRF), CO chemisorption, and Temperature-programmed desorption of hydrogen (H 2 -TPD). In contrast to the samples with conventional hydrogen reduction, there was almost no residual chlorine in the samples using RuCl 3 as precursor with hydrazine treatment. Furthermore, the dissolved aluminum could be removed much more easily in basic solution, which led to the higher BET surface and pore volume of hydrazine-reduction catalysts. Therefore, the active phase (Ru metal) would not be contaminated. Three main peaks, which occurred at about 150, 375, and 650°C, respectively, were observed in the H 2 -TPD profiles of Ru/Al 2 O 3 catalysts with a high amount of residual chlorine. A new peak of desorption hydrogen centering at 240°C, which was completely suppressed by the high amount of residual chlorine, might appear in the profiles of the samples with the washing procedure following hydrogen reduction or hydrazine treatment. The peaks with the desorption temperature lower than 500°C were relative with dissociatively adsorbed hydrogen and spillover hydrogen simultaneity, and the peak at above 500°C was caused by spillover hydrogen and would be stabilized by hydroxyl groups on alumina surface.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Physicochemical Characterization and H2-TPD Study of Alumina Supported Ruthenium Catalysts

Lin

Wang

et al. 2008

Catal Lett

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“…For example, impregnation of g-Al 2 O 3 with Ru III acetyl acetonate results in a catalyst highly selective towards c9,t11 and t10,c12 CLA isomer formation (i.e., 68-75 % selectivity) whereas impregnation with Ru III chloride trihydrate shows preference for t9,t11 CLA (40 % selectivity). [82] The authors explained this selectivity difference due to the acidic effect of Cl, which similar to acidic zeolites cause a preference for trans/trans CLA isomers.…”

Section: Clas From Linoleic Acid and Its Alkyl Estersmentioning

confidence: 97%

“…They showed that pretreatment of the metal catalysts with H 2 is not required for conjugation, but the activity of the catalyst is drastically increased when the catalyst is brought into contact with H 2 at elevated temperature prior to reaction. [82,84,91] In some examples, H 2 pretreatment for instance activates Ru/C by a factor of 30 for the diluted reactions in decane. One disadvantage of such treatment is competition with hydrogenation due to the presence of chemisorbed hydrogen on the metal surface.…”

Section: Clas From Linoleic Acid and Its Alkyl Estersmentioning

confidence: 99%

“…Moreover, many different CLA isomers are formed. This can also be explained by the above reaction mechanism, which can be divided in six different steps: [82] (1) migration of one double bond of linoleic acid, which results in the formation of CLA, (2) positional and geometric isomerization of CLA, (3) hydrogenation of one double bond of linoleic to mono-unsaturated fatty acid, (5) positional and geometric isomerization of mono-unsaturated fatty acids, and (6) hydrogenation of the double bond of a mono-unsaturated fatty acid to stearic acid.…”

Section: Mechanistic Considerationmentioning

confidence: 99%

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Catalytic Production of Conjugated Fatty Acids and Oils

et al. 2011

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The reactive double bonds in conjugated vegetable oils are of high interest in industry. Traditionally, conjugated vegetable oils are added to paints, varnishes, and inks to improve their drying properties, while recently there is an increased interest in their use in the production of bioplastics. Besides the industrial applications, also food manufactures are interested in conjugated vegetable oils due to their various positive health effects. While the isomer type is less important for their industrial purposes, the beneficial health effects are mainly associated with the c9,t11, t10,c12 and t9,t11 CLA isomers. The production of CLA-enriched oils as additives in functional foods thus requires a high CLA isomer selectivity. Currently, CLAs are produced by conjugation of oils high in linoleic acid, for example soybean and safflower oil, using homogeneous bases. Although high CLA productivities and very high isomer selectivities are obtained, this process faces many ecological drawbacks. Moreover, CLA-enriched oils can not be produced directly with the homogeneous bases. Literature reports describe many catalytic processes to conjugate linoleic acid, linoleic acid methyl ester, and vegetable oils rich in linoleic acid: biocatalysts, for example enzymes and cells; metal catalysts, for example homogeneous metal complexes and heterogeneous catalysts; and photocatalysts. This Review discusses state-of-the-art catalytic processes in comparison with some new catalytic production routes. For each category of catalytic process, the CLA productivities and the CLA isomer selectivity are compared. Heterogeneous catalysis seems the most attractive approach for CLA production due to its easy recovery process, provided that the competing hydrogenation reaction is limited and the CLA production rate competes with the current homogeneous base catalysis. The most important criteria to obtain high CLA productivity and isomer selectivity are (1) absence of a hydrogen donor, (2) absence of catalyst acidity, (3) high metal dispersion, and (4) highly accessible pore architecture.

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Direkte Umsetzung von Linolsäure an Silber‐Katalysatoren in Gegenwart von H₂: ein ungewöhnlicher Weg zu konjugierten Linolsäuren

Kreich

Claus

2005

Angewandte Chemie

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Isomerisierungen konjugierter Doppelbindungen mit Silber‐Katalysatoren in Gegenwart von Wasserstoff waren bislang nicht bekannt. Sie steuern die Selektivität der überaus schwierigen Isomerisierung von Linolsäure zu den physiologisch bedeutsamen 9‐cis,11‐trans‐ und 10‐trans,12‐cis‐ungesättigten Isomeren, die antikarzinogen und antiarteriosklerotisch wirken (siehe Schema; CLA=konjugierte Linolsäure).

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Influence of ruthenium precursor on catalytic activity of Ru/Al2O3 catalyst in selective isomerization of linoleic acid to cis-9,trans-11- and trans-10,cis-12-conjugated linoleic acid

Cited by 34 publications

References 22 publications

Physicochemical Characterization and H2-TPD Study of Alumina Supported Ruthenium Catalysts

Physicochemical Characterization and H2-TPD Study of Alumina Supported Ruthenium Catalysts

Catalytic Production of Conjugated Fatty Acids and Oils

Direkte Umsetzung von Linolsäure an Silber‐Katalysatoren in Gegenwart von H₂: ein ungewöhnlicher Weg zu konjugierten Linolsäuren

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Influence of ruthenium precursor on catalytic activity of Ru/Al2O3 catalyst in selective isomerization of linoleic acid to cis-9,trans-11- and trans-10,cis-12-conjugated linoleic acid

Cited by 34 publications

References 22 publications

Physicochemical Characterization and H2-TPD Study of Alumina Supported Ruthenium Catalysts

Physicochemical Characterization and H2-TPD Study of Alumina Supported Ruthenium Catalysts

Catalytic Production of Conjugated Fatty Acids and Oils

Direkte Umsetzung von Linolsäure an Silber‐Katalysatoren in Gegenwart von H2: ein ungewöhnlicher Weg zu konjugierten Linolsäuren

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Direkte Umsetzung von Linolsäure an Silber‐Katalysatoren in Gegenwart von H₂: ein ungewöhnlicher Weg zu konjugierten Linolsäuren