Outstanding Performances of Magnesia-Supported Platinum–Tin Catalysts for Citral Selective Hydrogenation

Recchia, Sandro; Dossi, Carlo; Poli, Nicola; Fusi, A.; Sordelli, Laura; Psaro, Rinaldo

doi:10.1006/jcat.1999.2485

Cited by 58 publications

(50 citation statements)

References 12 publications

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“…lic catalysts are also suitable [8][9][10][11][12][13][14]. For the technical citral hydrogenation to geraniol/nerol carbon supported Ru catalysts in the presence of tertiary amines are frequently used [15,16].…”

Section: Martin Steffanmentioning

confidence: 99%

Selective Hydrogenation of Citral in an Organic Solvent, in a Ionic Liquid, and in Substance

et al. 2007

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It is investigated whether the catalyst system Ag-In/SiO 2 can be applied in the selective hydrogenation of citral, with the aim of synthesizing the acyclic, allylic terpene alcohols geraniol/nerol with high selectivity and space-time yield. In addition, as liquid-phase hydrogenations are often also influenced by the choice of solvent, it is of interest to know how the solvent, in particular in terms of its polarity and hydrogen solubility, affects the activity and the selectivity of catalysts during hydrogenation of the a,b-unsaturated aldehyde citral. ProblemTerpenes are a low-cost class of compounds for the production of fragrances, flavors and pharmaceuticals, with terpenoid hydrocarbons (e.g., myrcene) being used less than terpene alcohols (e.g., geraniol, nerol, citronellol) and aldehydes (e.g., citral, citronellal). The compounds are often extracted from essential oils (e.g., lemon grass oil, citrus oil) by fractional distillation. Geraniol is the most frequently used terpenoid fragrance compound and, like its isomer nerol, applied in perfumes of roses and in citrus fragrances [1,2]. As an a,b-unsaturated aldehyde citral itself is an important educt for the synthesis of terpene alcohols and aldehydes because of its three functionalities (carbonyl group, conjugated C=C bond, isolated C=C bond) and thus, with the right choice of catalyst and reaction conditions, enables the synthesis of geraniol/ nerol, citronellal and/or citronellol by selective hydrogenation. Fig. 1 shows the reaction network of citral hydrogenation up to the completely hydrogenated reaction product 3,7-dimethyloctan-1-ol.In academia, citral hydrogenation is often used as a model reaction to study the influence of metal specificities, support materials and solvents on the intramolecular selectivitiy and product yield [3][4][5][6]. From a vulcano plot of the specific activity (turnover frequency) vs. the %-d character [7] of the metal used at 300 K and 0.1 MPa hydrogen pressure it follows, as expected, that Pd is the most active metal, whereas Ni, Co and Rh catalysts exhibit an activity which is about one to two orders of magnitude lower [6] (1) = 3,7-dimethyl-2-octenal, (2) = dihydrocitronellal, (3) = 3,7-dimethyl-2-octenol, (4) = 3,7-dimethyloctan-1-ol.

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Section: Martin Steffanmentioning

confidence: 99%

Selective Hydrogenation of Citral in an Organic Solvent, in a Ionic Liquid, and in Substance

et al. 2007

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“…Pt/MgO-based catalysts were used in hydrogenation of citral [19] and crotonaldehyde [20]. During hydrogenation of citral the monometallic Pt/MgO catalyst exhibited a selectivity of about 70 %.…”

Section: Introductionmentioning

confidence: 99%

Hydrogenation of Cinnamaldehyde over Pt‐Modified Molecular Sieve Catalysts

Hájek¹,

Kumar²,

Francová³

et al. 2004

Chem Eng & Technol

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The catalytic properties of various Pt-modified molecular sieves were tested in liquid-phase hydrogenation of cinnamaldehyde and compared to Pt/MgO and commercial Pt/C catalysts. The type of support considerably influenced the catalytic properties. The superior selectivity performance of microporous catalysts was confirmed; the highest selectivity to allyl alcohol of about 40 % was obtained over the beta support whereas the mesoporous MCM-41-supported catalyst was unselective. The highest activity was obtained over the Pt/mordenite catalyst. In order to clarify the performance of catalysts, several characterization methods (XRD, XRF, FTIR, surface measurements) were employed.

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“…Although there are only a few reports of MgO-supported bimetallic catalysts incorporating just group-8 metals, there are a number of examples of MgO-supported catalysts incorporating platinum with an oxophilic metal, including, Pt-Sn/MgO prepared from Pt(acac) 2 and Sn(n-C 4 H 9 ) 4 by a two-step impregnation [5], and PtW/MgO [6] and PtMo/MgO [7], prepared by slurrying MgO powder with pentane solutions of {Pt[W(CO) 3 (C 5 H 5 )] 2 (PhCN) 2 } and {Pt[Mo(CO) 3 (C 5 H 5 )] 2 (PhCN) 2 }, respectively. The characterizations of these samples show that the oxophilic metal helps to maintain and stabilize high dispersions of the platinum [8].…”

Section: Introductionmentioning

confidence: 99%

MgO-supported cluster catalysts with Pt–Ru interactions prepared from Pt3Ru6(CO)21(μ3-H)(μ-H)3

et al. 2007

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Bimetallic MgO-supported catalysts were prepared by adsorption of Pt 3 Ru 6 (CO) 21 (l 3 -H)(l-H) 3 on porous MgO. Characterization of the supported clusters by infrared (IR) spectroscopy showed that the adsorbed species were still in the form of metal carbonyls. The supported clusters were decarbonylated by treatment in flowing helium at 300°C, as shown by IR and extended X-ray absorption fine structure (EXAFS) data, and the resulting supported PtRu clusters were shown by EXAFS spectroscopy to have metal frames that retained Pt-Ru bonds but were slightly restructured relative to those of the precursor; the average cluster size was almost unchanged as a result of the decarbonylation. These are among the smallest reported bimetallic clusters of group-8 metals. The decarbonylated sample catalyzed ethylene hydrogenation with an activity similar to that reported previously for c-Al 2 O 3 -supported clusters prepared in nearly the same way and having nearly the same structure. Both samples were also active for n-butane hydrogenolysis, with the MgO-supported catalyst being more active than the c-Al 2 O 3 -supported catalyst.

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Outstanding Performances of Magnesia-Supported Platinum–Tin Catalysts for Citral Selective Hydrogenation

Cited by 58 publications

References 12 publications

Selective Hydrogenation of Citral in an Organic Solvent, in a Ionic Liquid, and in Substance

Selective Hydrogenation of Citral in an Organic Solvent, in a Ionic Liquid, and in Substance

Hydrogenation of Cinnamaldehyde over Pt‐Modified Molecular Sieve Catalysts

MgO-supported cluster catalysts with Pt–Ru interactions prepared from Pt3Ru6(CO)21(μ3-H)(μ-H)3

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