- Ring opening of decalin and methylcyclohexane over bifunctional Ir/WO 3/Al2O3 catalysts
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Ring-opening reactions of decalin and methylcyclohexane (MCH) over bifunctional catalysts (1.2Ir/WO3/Al2O3) were investigated. A series of catalysts containing up to 5.3 at. W/nm2 and 1.2 wt.% Ir was prepared. The acidity of the solids was monitored by low-temperature CO adsorption followed by infrared spectroscopy. Characterization of the Ir metal phase was performed by H2 chemisorption and X-ray diffraction. The activity and product selectivity patterns obtained for the decalin ring-opening reaction were compared with those observed for MCH. For both naphthenes, ring contraction precedes ring opening, suggesting a similar ring-opening mechanism. Kinetic modeling based on the proposed reaction network allowed the determination of the activation energies and initial rates. Based on the yields and products distribution obtained for the decalin reaction, the potential for improvement of the cetane number is discussed.
- Moraes, Rodrigo,Thomas, Karine,Thomas, Sebastien,Van Donk, Sander,Grasso, Giacomo,Gilson, Jean-Pierre,Houalla, Marwan
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- Ring opening of decalin and methylcyclohexane over alumina-based monofunctional WO3/Al2O3 and Ir/Al 2O3 catalysts
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Ring-opening reactions of decalin and MCH were studied over monofunctional acid (WO3/Al2O3) and metal (Ir/Al 2O3) catalysts containing, respectively, up to 5.3 at. W/nm2 and 1.8 wt% Ir. The catalysts were characterized by X-ray diffraction, Raman spectroscopy, low-temperature CO adsorption followed by infrared spectroscopy, and H2 chemisorption. A reaction network was proposed for both molecules and used to determine the kinetic parameters. Kinetic modeling allowed relating characterization results and catalytic performance. For WO3/Al2O3 catalysts, ring contraction precedes ring opening of both molecules. The evolution of ring contraction activity was consistent with the development of relatively strong Bronsted acid sites. Ring opening occurs according to a classic acid mechanism. For Ir/Al2O3 catalysts, only direct ring opening was observed. Ring opening proceeds mostly via dicarbene mechanism. Analysis of products indicated that monofunctional metal catalysts are better suited than acid solids for upgrading LCO.
- Moraes, Rodrigo,Thomas, Karine,Thomas, Sebastien,Van Donk, Sander,Grasso, Giacomo,Gilson, Jean-Pierre,Houalla, Marwan
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scheme or table
p. 62 - 77
(2012/03/11)
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- Catalytic activity of the VIII group metals in the hydrogenation and isomerization of α- And β-pinenes
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The kinetic regularities of the liquid-phase hydrogenation and isomerization of α- and β-pinenes over the Pd/C, Ru/C, Rh/C, Pt/C, and Ir/C catalysts were studied at temperatures ranging from 20 to 100 °C and at hydrogen pressures of 1-11 bar using n-octane as the solvent. The hydrogenation and isomerization of α- and β-pinenes occur simultaneously on the Ru/C, Rh/C, Pt/C, and Ir/C catalysts, and the reaction mixture contains the products of double bond hydrogenation, viz., cis- and trans-pinanes. The Ru, Rh, and Pd metals have a higher catalytic activity in β-pinene isomerization than Ir and Pt. Among the VIII Group metals studied, the Pd-based catalyst has the highest catalytic activity in double bond isomerization of α- and β-pinenes. The general scheme of the mechanism of hydrogenation and isomerization of α- and β-pinenes on the Pd/C catalyst was proposed.
- Deliy,Simakova
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body text
p. 2056 - 2064
(2010/05/02)
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- Alkylation of alkenes: Ethylaluminum sesquichloride-mediated hydro-alkyl additions with alkyl chloroformates and di-tert-butylpyrocarbonate
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A general method for the hydro-alkyl addition to the nonactivated C=C double bond of alkenes using alkyl chloroformates (primary, secondary), 12, and di-tert-butylpyrocarbonate, 52, mediated by ethylaluminum sesquichloride (Et3Al2Cl3) has been developed. Reaction of 12 and 52, respectively, with Et3Al2Cl3 gives an alkyl cation which is added to the alkene; hydride transfer to the adduct carbenium ion or, if applicable, 1,2-H shift followed by hydride transfer from Et3Al2Cl3 to the rearranged adduct carbenium ion gives the saturated addition product. The reaction has been applied to 1-alkenes, 2-methyl-1-alkenes, internal double bonds, and to three cyclic alkenes. Special interest has been focused on alkylations of unsaturated fatty compounds, such as oleic acid (2), which are important renewable feedstocks. 2-Methylalkanes, 3-methylalkanes, 2,4-dimethylalkanes, 2,3-dimethylalkanes, 2,2,4-trimethylalkanes, cyclohexylalkanes, and carboxylic acids and esters with the respective branched alkyl chain have been synthesized with good to moderate yields.
- Biermann, Ursula,Metzger, Juergen O.
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p. 10319 - 10330
(2007/10/03)
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- STUDIES OF COMPOUNDS IN THE MENTHANE SERIES. XIX. SYNTHESIS AND PROPERTIES OF TRANS-o-4-MENTHEN-8-OL AND STEREOISOMERIC o-5-METHEN-8-OLS
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Trans-o-4-Menthen-8-ol and cis- and trans-o-5-menthen-8-ols have been prepared via the Diels-Alder reactions of 1,3-butadiene with crotonaldehyde in the presence of boron trifluoride etherate, and piperylene with methyl acrylate, respectively.The dehydration reactions of these alcohols have been studied in the presence of acetic anhydride and potassium bisulfate; the latter reagent demonstrates a high reaction selectivity.
- Bazyl'chik, V. V.,Fedorov, P. I.,Klyuev, N. A.,Dank, E. Kh.
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p. 1320 - 1327
(2007/10/02)
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- INVESTIGATION OF COMPOUNDS OF THE o-METHANE SERIES. XII. INVESTIGATION OF THE COMPOSITION OF THE PRODUCTS FROM PYROLYSIS OF VERBENENE
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During the pyrolysis of verbenene the opening of the cyclobutane ring occurs at the C1-C7 and C5-C7 bond with the formation of terpene compounds of the o- and p-methane series.The latter were submitted to secondary reactions of isomerization and disproportionation of hydrogen, leading to the reduction of monocyclic and bicyclic terpene and aromatic hydrocarbons and unsaturated compounds of the isobutylcyclohexane series.
- Bazyl'chik, V. V.,Fedorov, P. I.,Skakovskii, E. D.,Vinogradov, L. I.
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p. 268 - 272
(2007/10/02)
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- APPLICATION OF 1H NMR AND 13C NMR FOR ESTABLISHING THE SPATIAL STRUCTURE OF STEREOISOMERIC o- AND p-MENTHANE, o- AND p-MENTHENES, AND ISOPROPYLCYCLOHEXANE.
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An attempt to establish the spatial structure of stereoisomeric o- and p-menthanes, 8-o- and 8-p-menthenes, and isopropylcyclohexane on the basis of an analysis of the **1H NMR and **1**3C NMR spectra is described.
- Bazyl'chik,Samitov,Ryabushkina
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p. 543 - 548
(2007/10/02)
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- INVESTIGATION OF COMPOUNDS IN THE o-MENTHANE SERIES XI. ISOMERIZATION TRANSFORMATIONS OF o-1,4-MENTHADIENES
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Under the conditions of base catalysis under the influence of potassium tert-butoxide in dimethyl sulfoxide and lithium and calcium amides o-1,4-menthadiene forms equilibrium mixtures of o-1,3-menthadiene, o-1,5-menthadiene, and the skeletal rearrangement product 1-isopropyl-5-ethylidenecyclopentene.In the presence of NaX and KX zeolites competing dehydrogenation and disproportionation of the hydrogen occur in o-1,4-menthadiene with the formation of a mixture of o-menthenes and o-cymene.With increase in temperature the dehydration process becomes determining.With acid catalysis the transformation of o-1,4-menthadiene into 1-isopropyl-5-ethylidenecyclopentene and dehydration to o-cymene are the mainpaths.
- Bazyl'chik, V. V.,Fedorov, P. I.
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p. 1221 - 1227
(2007/10/02)
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