- Ring-opening of Alkyl-substituted Cyclopropanes in the Presence of Hydrogen on Copper
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In the presence of hydrogen on copper, the cyclopropanes (1), (2), and (3) are transformed into saturated hydrocarbons containing the same number of carbon atoms (alkenes are also formed, through isomerization of the cyclopropanes); these studies reveal the importance of a previously unknown property of copper in heterogeneous metal catalysis.
- Bartok, Mihaly,Palinko, Istvan,Molnar, Arpad
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- Activation and isomerization of hydrocarbons over WO3/ZrO2 catalysts. II. Influence of tungsten loading on catalytic activity: Mechanistic studies and correlation with surface reducibility and tungsten surface species
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We studied the correlation among the catalytic behavior of WO3/ZrO2 samples toward unsaturated and saturated hydrocarbons transformation, tungsten surface species oxidation states, and the crystallographic structure of the zirconia support. Different tungsten-loaded catalysts were studied, from 9 wt% (near-monolayer coverage) to 30 wt%. The resulting WO3/ZrO2 materials were obtained by impregnation of a tungsten salt on either a commercially available monoclinic zirconia or an amorphous hydroxide, ZrOx(OH)4-2x, followed by a calcination step (according to the Hino and Arata procedure), leading to a tetragonal structure. In contrast to previous works, here we demonstrate that the crystallographic structure of zirconia has no influence on catalytic properties. Correlations with XPS analyses revealed two aspects of catalytic behavior that depend strongly on the catalyst reducibility and thus on the W surface species oxidation states. First, on hardly reducible (tungsten loadings a purely acidic monomolecular mechanism for both isomerization (largely predominant) and cracking reactions, associated with W6+ and W5+ surface species, was demonstrated. Second, on easily reducible (tungsten loadings >15 wt%) or deeply reduced (over 723 K) surfaces, a bifunctional mechanism associating dehydrogenating/hydrogenating properties occurring on metallic tungsten and acidic isomerization and cracking on W5+ and W6+ surface species was observed. However, in this last case, we could not exclude the participation of a purely metallic isomerization mechanism occurring through σ-alkyl adsorbed species on the β-W metallic phase. A more pronounced reduction then led to an increase in the extensive hydrogenolysis mechanism, causing catalyst deactivation.
- Di Gregorio, Francois,Keller, Nicolas,Keller, Valerie
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- Reaction Mechanisms of Isomerization and Cracking of Heptane on Pd/H-Beta Zeolite
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Tha vapor-phase isomerization and cracking of heptane on H-Beta zeolites loaded with various amounts of Pd metal has been studied at a temperature of 505 K and at a total pressure of 0,3 MPa.The cracking of heptane is interpreted as a combination of classic bifunctional hydrocracking and dimerization cracking.The isomerization of heptane proceeds through the classic-bifunctional mechanism and a second mechanism involving dimerization cracking.The contribution of the different mechanisms to the izomerization and cracking is derived from the formation of specific reaction products.The contribution of the different mechanisms is dependent on the Pd content of the zeolite.
- Blomsma, E.,Martens, J. A.,Jacobs, P. A.
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- Selective methylative homologation: An alternate route to alkane upgrading
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InI3 catalyzes the reaction of branched alkanes with methanol to produce heavier and more highly branched alkanes, which are more valuable fuels. The reaction of 2,3-dimethylbutane with methanol in the presence of InI3 at 180-200°C affords the maximally branched C7 alkane, 2,2,3-trimethylbutane (triptane). With the addition of catalytic amounts of adamantane the selectivity of this transformation can be increased up to 60%. The lighter branched alkanes isobutane and isopentane also react with methanol to generate triptane, while 2-methylpentane is converted into 2,3-dimethylpentane and other more highly branched species. Observations implicate a chain mechanism in which InI3 activates branched alkanes to produce tertiary carbocations which are in equilibrium with olefins. The latter react with a methylating species generated from methanol and InI 3 to give the next-higher carbocation, which accepts a hydride from the starting alkane to form the homologated alkane and regenerate the original carbocation. Adamantane functions as a hydride transfer agent and thus helps to minimize competing side reactions, such as isomerization and cracking, that are detrimental to selectivity.
- Bercaw, John E.,Hazari, Nilay,Labinger, Jay A.,Scott, Valerie J.,Sunley, Glenn J.
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- Mechanism of Isomerization of Hydrocarbons on Metals. Part 9.-Isomerization and Dehydrocyclization of 2,3-Dimethyl(2-(13)C)pentane on a 10percent Pt-Al2O3 Catalyst
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The isomerization, dehydrocyclization and hydrogenolysis of 2,3-dimethyl(2-(13)C)pentane have been studied at 260 deg C over a 10percent Pt-Al2O3 catalyst of low dispersion, under various hydrocarbon and hydrogen pressures.Most of the isomerization products are accounted for either by a bond-shift mechanism or by a cyclic mechanism involving 1,2-dimethylcyclopentane intermediate.The absence of significant scrambling of the label suggests that the rate-determining step in isomerization is the skeletal rearrangement of highly dehydrogenated species.The positive order as a function of hydrogen which is found (0.8-1.2) cannot then be taken as evidence that desorption is rate-determining.It is best explained by assuming multisite adsorption of hydrocarbon and competition with hydrogen for chemisorption on the same sites.The results provide argument in favour of a reactive rather than dissociative-type adsorption step.
- Parayre, Patrick,Amir-Ebrahimi, Valia,Gault, Francois G.,Frennet, Alfred
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- Isomerization of n-Heptane over Pd-Loaded Silico-Alumino-Phosphate Molecular Sieves
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Isomerization of n-heptane was studied on a series of bifunctional SAPO-based catalysts with contents of 0.1 wtpercent Pd.From results on temperature programmed desorption of NH3 it is deduced that the different molecular sieve structures contain nearly identical amounts of silicon substituting for phosphorus in the framework (0.3 to 0.5 silicon atoms per unit cell).Best activities and selectivities for branched heptane isomers are achieved with SAPO-11 and SAPO-31.SAPO-17 and SAPO-5 show substantially lower activities.With SAPO-5, there is a high cracking selectivity which is assumed to be caused by the reduced accessibility of parts of the bridged hydroxyl groups within the molecular sieve framework.Different locations of these acid sites are evidenced by infrared OH vibration spectra recorded after adsorption of n-heptane.
- Parlitz, B.,Schreier, E.,Zubowa, H. -L.,Eckelt, R.,Lieske, E.,et al.
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- Mechanism of Isomerization of Hydrocarbons on Metals. Part 11.-Isomerization and Dehydrocyclization of (13)C-labelled 3-Methylhexanes on Pt-Al2O3 Catalysts
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The isomerization, dehydrocyclization and hydrogenolysis of 3-methylhexane have been studied at 320-380 deg C over a series of Pt-Al2O3 catalysts with a metal dispersion extending from 0.05 to 1.The use of five labelled compounds, 3-methyl(1-(13)C), (2-(13)C), (3-(13)C), (6-(13)C)hexanes and 3-methyl((13)C)hexane, alloved distinction between the various parallel pathways.On all catalysts the predominant reaction was the isomerization according to a cyclic mechanism involving either 1,3-dimethyl-, 1,2-dimethyl- or ethyl-cyclopentane intermediates with a relative contribution of 60, 40 and 20 percent, respectively.These results are consistent wiith a dehydrocyclization scheme involving a metallocarbene as precursor and dicarbene or dicarbyne recombination as the rate-determining step.
- Amir-Ebrahimi, Valia,Gault, Francois G.
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- Influence of the Br?nsted acidity, SiO2/Al 2O3 ratio and Rh-Pd content on the ring opening. Part II. Selective ring opening of methylcyclohexane
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Monometallic and bimetallic Pd-Rh catalysts with various Rh/Pd atomic ratios (=0.5, 1 and 2) and a total metal charge of 1 wt% supported on SiO 2-Al2O3 (SIRAL 40, 20, 5) were studied for the ring opening of methylcyclohexane (MCH). The results were compared with those obtained previously for ring opening of decalin. It was found that the total acidity and the Br?nsted acidity of the support have a higher influence on the activity for ring opening of naphthenic bicycles than on the activity for opening single rings. The influence of the metal charge is more important on the reaction of MCH. All the catalysts display a high MCH conversion, which increases with the reaction temperature. The bimetallic catalyst with the Rh/Pd ratio equal to 2 and supported on SIRAL 40 has the highest yield to ring opening products.
- D'Ippolito, Silvana A.,Especel, Catherine,Vivier, Laurence,Epron, Florence,Pieck, Carlos L.
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- Silica-supported dendrimer-palladium complex-catalyzed selective hydrogenation of dienes to monoolefins
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The selective hydrogenation of cyclic and acyclic dienes to monoolefins occurs under very mild conditions, in the presence of silica-supported PAMAM-Pd complexes. The activity and selectivity of this reaction is sensitive to the dendrimer structure. These dendritic complexes display excellent recycle properties, retaining activity for up to eight recycles.
- Zweni, Pumza P.,Alper, Howard
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- Alkanethiolate-capped palladium nanoparticles for selective catalytic hydrogenation of dienes and trienes
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Selective hydrogenation of dienes and trienes is an important process in the pharmaceutical and chemical industries. Our group previously reported that the thiosulfate protocol using a sodium S-alkylthiosulfate ligand could generate catalytically active Pd nanoparticles (PdNP) capped with a lower density of alkanethiolate ligands. This homogeneously soluble PdNP catalyst offers several advantages such as little contamination via Pd leaching and easy separation and recycling. In addition, the high activity of PdNP allows the reactions to be completed under mild conditions, at room temperature and atmospheric pressure. Herein, a PdNP catalyst capped with octanethiolate ligands (C8 PdNP) is investigated for the selective hydrogenation of conjugated dienes into monoenes. The strong influence of the thiolate ligands on the chemical and electronic properties of the Pd surface is confirmed by mechanistic studies and highly selective catalysis results. The studies also suggest two major routes for the conjugated diene hydrogenation: the 1,2-addition and 1,4-addition of hydrogen. The selectivity between two mono-hydrogenation products is controlled by the steric interaction of substrates and the thermodynamic stability of products. The catalytic hydrogenation of trienes also results in the almost quantitative formation of mono-hydrogenation products, the isolated dienes, from both ocimene and myrcene.
- Chen, Ting-An,Shon, Young-Seok
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- HETEROGENEOUS DEOXYGENATION OF KETONES
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Relatively unhindered ketones are converted directly to the corresponding hydrocarbons in the presence of hydrogen at normal pressures and a Ni/Al2O3 catalyst in a simple gas-phase reactor.
- Maier, W. F.,Bergmann, K.,Bleicher, W.,Schleyer, P. v. R.
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- A novel route for the synthesis of alkanes from glycerol in a two step process using a Pd/SBA-15 catalyst
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Glycerol is produced as a valuable by-product in the transesterification of fatty acids, but it cannot be used directly as a fuel additive. In this study, we developed a systematic conversion for glycerol, which proceeds via synthesizing the key intermediate, 1,2,3-tribromopropane and using the Suzuki coupling reaction to introduce the alkyl group. A series of Pd/SBA-15 catalysts with different wt% of Pd (10%, 15% and 20%) was prepared by a one step sol-gel method. The structure and composition of the catalysts were characterized by X-ray diffraction analysis (XRD), N2 adsorption-desorption isotherms, transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectrometry (ICP-OES). The metallic state of dispersed palladium in SBA-15 is confirmed with X-ray photoelectron spectroscopy (XPS). Pd/SBA-15 with a Pd loading of 20 wt% shows good catalytic activity at 90 °C with methylboronic acid, allowing the complete conversion of 1,2,3-tribromopropane and 64% selectivity of 3-methylpentane. The optimized catalysts were also employed in coupling reactions between various alkylhalides and methylboronic acid, which obtained the desired product with an excellent selectivity. The catalyst can be successfully recycled five times. After the first cycle, we observed a drop in activity with 20% Pd/SBA-15, which was due to the leaching of palladium but in the later cycles, there was no significant decrease in activity.
- Udayakumar,Pandurangan
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p. 78719 - 78727
(2015/10/05)
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- Influence of chlorine on the catalytic properties of supported rhodium, iridium and platinum in ring opening of naphthenes
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Pt, Ir and Rh were deposited on SiO2 or Al2O 3 using chlorinated precursors and various amounts of HCl in the impregnation medium. The Br?nsted and Lewis acidities increased with the chlorine content of the alumina supported catalysts. The silica-supported catalysts only presented Lewis acid sites. The catalysts were evaluated in methylcyclopentane (MCP) and methylcyclohexane (MCH) ring-opening (RO) under pressure (2.85 and 3.95 MPa, respectively), from 200 to 425 C. For MCP conversion, the acidity of the alumina support had no sensitive effect on the activity and selectivity to RO products, and few effects on the distribution of RO products. No isomerization or hydrocracking products were observed, confirming that these reactions occurred mainly on the metal function, which was not modified by the presence of chlorine. The nature of the support, SiO 2 or Al2O3, had a strong effect on both the activity (1.9 against 0.5 mol h-1 g-1metal for Ir/Al2O3 and Ir/SiO2, respectively at 225 C) and selectivity to RO products (99.6% against 97.5% for Ir/Al2O 3 and Ir/SiO2, respectively, at 80% of MCP conversion) for Ir catalysts only. Interestingly, the Rh/SiO2 exhibited a high selectivity for converting MCP to RO products, similar to Ir/Al 2O3, i.e. 99.6% at 80% of conversion. Depending on the metal and the supports, three types of behavior were observed for MCH ring-opening: (i) a direct ring-opening on the metal function whatever the support for Ir, (ii) a first step of isomerization, and then a need of a sufficiently acidic support, for Pt and (iii) an intermediate behavior for Rh, which was able to either directly convert MCH in absence of acidic support or favor a bifunctional mechanism on chlorinated alumina.
- Samoila,Epron,Marécot,Especel
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p. 207 - 219
(2013/07/26)
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- A novel iron complex for cross-coupling reactions of multiple C-Cl bonds in polychlorinated solvents with grignard reagents
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A novel iron(III) complex (2) of a pincer ligand [1, N2,N6-bis(2,6- diisopropylphenyl)pyridine-2,6-dicarboxamide] was developed and used for remediation of polychlorinated solvents via sp3-sp3 coupling of Grignard reagents with C-Cl bonds. The use of an iron catalyst for such coupling reactions is highly desirable due to its greener and more economical nature. Complex 2 was characterized using various spectroscopic techniques: electrospray ionization mass spectrometer (ESI-MS, m/z 575.1), cyclic voltammetry (E 1/2, 0.03 V and ΔE, 0.97 V), and ultraviolet visible (UV/Vis) spectroscopic techniques. The iron(III) complex showed efficient activation of multiple C-Cl bonds and catalyzing C-C coupling of polychlorinated alkyl halides, such as dichloromethane (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), with various Grignard reagents under ambient reaction conditions. Complex 2 showed exceptional activity with reactions approaching near completion in about 5 min. With the required catalyst loading as low as 0.2 mol%, considerably high turnover numbers (TON = 483) and turnover frequency (TOF = 5,800 h-1) were obtained. None of the products detected during the reaction contained any chlorine, indicating an efficient dechlorination method while synthesizing products of synthetic and commercial interest. Interestingly, the catalyst was capable of replacing all chlorine atoms in each polychlorinated solvent under the investigations with high conversion. Springer Science+Business Media, LLC 2012.
- Gartia, Yashraj,Pulla, Sharon,Ramidi, Punnamchandar,Farris, Carolina Costa,Nima, Zeid,Jones, Darin E.,Biris, Alexandru S.,Ghosh, Anindya
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p. 1397 - 1404
(2013/01/15)
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- Cross coupling reactions of multiple CCl bonds of polychlorinated solvents with Grignard reagent using a pincer nickel complex
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The nickel(II) complex of a bulky pincer-type ligand, N,N′-bis(2,6- diisopropylphenyl)-2,6-pyridinedicarboxamido, was examined for sp 3-sp3 coupling of Grignard reagents with polychlorinated solvents. The nickel(II) complex catalyzed CC coupling of polychlorinated alkyl halides, such as dichloromethane (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), with various Grignard reagents. The effective activation of multiple CCl bonds proceeded under ambient reaction conditions and within a short time (20 min). This catalyst displays the highest activity yet reported for this reaction type, with catalyst loading as low as 0.4 mol% and turnover frequency (TOF) as high as 724 h-1. The catalyst is capable of replacing all chlorine atoms with CC bond formations for all of the polychlorinated solvents under investigation. The catalytic process could prove to be an efficient method of remediation of toxic polychlorinated solvents while generating synthetically and commercially important chemicals.
- Gartia, Yashraj,Nasini, Udaya Bhasker,Ghosh, Anindya,Biswas, Abhijit,Stadler, Matthew
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p. 322 - 327,6
(2020/07/30)
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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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- PROCESS FOR THE PRODUCTION OF A HYDROCARBON
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A method of alkane homologation is provided, comprising contacting: a reactive alkane; a methylating agent; an optional diamondoid modifier; and an activating catalyst, thereby generating a hydrocarbon product having a greater number of carbon atoms than the reactive alkane.
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Page/Page column 27-28
(2009/06/27)
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- Hydrocarbon separation
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Process for the separation of close boiling compounds comprising distilling a hydrocarbon mixture of said compounds in the presence of a high boiling diluent liquid and a solid adsorbent. The high boiling diluent is withdrawn from the bottom of the distillation column and recycled to the column. The process is particularly suitable for the separation of straight-chain isomers from isomerate mixtures, the separation of benzene from hydrocarbon mixtures and the separation of paraffins from olefins.
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Page/Page column 11
(2008/12/06)
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- SYSTEM AND PROCESS FOR FISCHER-TROPSCH CONVERSION
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A method for forming C2+ hydrocarbons by forming a dispersion comprising synthesis gas bubbles dispersed in a liquid phase comprising hydrocarbons in a high shear device, wherein the average bubble diameter of the synthesis gas bubbles is less than about 1.5 microns, introducing the dispersion into a reactor, and removing a product stream comprising C2+ hydrocarbons from the reactor. A system for converting carbon monoxide and hydrogen gas into C2+ hydrocarbons including at least one high shear mixing device comprising at least one rotor and at least one stator separated by a shear gap, wherein the high shear mixing device is capable of producing a tip speed of the at least one rotor of greater than 22.9 m/s (4,500 ft/min), and a pump configured for delivering a fluid stream comprising liquid medium to the high shear mixing device.
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Page/Page column 25-27
(2009/03/07)
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- PROCESS FOR THE PRODUCTION OF A HYDROCARBON
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A process for the production of a hydrocarbon which comprises contacting, in a reactor, methanol and/or dimethyl ether with a catalyst comprising a metal halide, such as a zinc halide, in which the methanol and/or dimethyl ether is contacted with the catalyst in the presence of at least one phosphorus compound having at least one P-H bond.
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Page/Page column 19-20; 25-26
(2008/06/13)
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- Paraffin alkylation
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A liquid acid process is disclosed in which a hydrocarbon component containing an olefin, an olefin precursor or mixture and an isoalkane and a liquid acid catalyst is fed to a downflow reaction zone containing a disperser, under conditions to induce pulse flow at or near the outlet to react the isoalkane and olefin to produce a reaction product and feeding the reaction product to a vaporization zone containing a disperser under conditions to induce pulse flow at or near the outlet of the vaporization zone. A pressure drop across the disperser in the vaporization zone causes partial vaporization of the hydrocarbon which quench es the heat reaction and cooling the unvaporized portion of said reaction product, which is recovered and allowed to separate into an acid phase and hydrocarbon phase containing the alkylate. The acid catalyst and hydrocarbons may be fractally fed to the reaction zone.
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Page/Page column 7
(2008/06/13)
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- Process for the preparation of a paraffin isomerization catalyst
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A process for preparation of a paraffin isomerization catalyst comprising a mixture of a Group IVB metal oxide, a Group VIB metal oxide, a Group IIIA metal oxide and a Group VIII metal. The process includes the steps of: a) contacting a hydroxide of the Group IVB metal with an aqueous solution of an oxyanion of the Group VIB metal to provide a mixture, (b) drying the mixture to provide a dry powder, (c) kneading the powder with a Group IIIA hydroxide gel and a polymeric cellulose ether compound to form a paste, (d) shaping the paste to form a shaped material, (e) calcining the shaped material to form a calcined material, (f) impregnating the calcined material with an aqueous solution of a Group VIII metal salt to provide the catalyst, and (g) calcining the catalyst.
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(2008/06/13)
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- Isomerization of N-heptane in naphtha cuts
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A process for the isomerization of normal heptane contained within a naphtha stream, such as a C6-C8 naphtha, in which the naphtha stream is fractionated into a fraction substantially free of normal heptane and a fraction containing normal heptane. The fraction containing normal heptane is contacted with an isomerization catalyst in an isomerization zone operated as a singe pass fixed bed reactor having a single effluent to isomerize a portion of said normal heptane to branched heptane. The effluent is recovered from said isomerization zone and the effluent is fractionated to recover said branched heptane. The unconverted normal heptane is recovered and returned to the isomerization since it can be separated from the branded heptanes by fractionation.
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Page/Page column 4
(2008/06/13)
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- Alkylation process with recontacting in settler
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A system and/or process for decreasing the level of at least one organic fluoride present in a hydrocarbon phase contained in an alkylation settler by contacting the hydrocarbon phase with an HF containing stream, containing greater than about 80 wt. % and less than about 94 wt. % HF, in the intermediate portion of the settler which contains at least one tray system, with each tray system comprising a perforated tray defining a plurality of perforations and a layer of packing below the perforated tray, are disclosed.
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Page/Page column 3-5
(2008/06/13)
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- Chemical transformations of isopentane and isooctane in trifluoromethanesulfonic acid
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The process of isopentane and isooctane activation in trifluoromethanesulfonic acid (H0 = -14) has been studied by GC/MS and NMR. The results show evidence for a high reactivity of isopentane. Various mechanisms constructed using the experimental data and the results of nonempirical quantum-mechanical calculations are compared, and it is concluded that a key role in the reaction under consideration is played by the direct electrophilic attack of CF3SO3H at the C2-C3 bond of isooctane. Copyright
- Gekhman,Smurnyi,Ustynyuk
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p. 1766 - 1770
(2007/10/03)
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- Process of paraffin hydrocarbon isomerisation catalysed by an ionic liquid in the presence of a cyclic hydrocarbon addditive
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A process for the conversion of linear and/or branched paraffins hydrocarbons, catalysed by an ionic liquid catalyst, in the presence of a cyclic hydrocarbon additive containing a tertiary carbon atom. The presence of the specific hydrocarbon additives influences the reaction mechanism by increasing the selectivity towards the formation of paraffin hydrocarbons with a higher degree of branching.
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- Isomerization catalyst and processes
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A catalyst and process is disclosed to selectively upgrade a paraffinic feedstock to obtain an isoparaffin-rich product for blending into gasoline. The catalyst comprises a support of a tungstated oxide or hydroxide of a Group IVB (IUPAC 4) metal, a first component of at least one lanthanide element, yttrium or mixtures thereof, which is preferably ytterbium or holmium, and at least one platinum-group metal component which is preferably platinum.
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- Catalyst and process for contacting a hydrocarbon and ethylene
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A process of contacting at least one feed hydrocarbon, containing three to about seven carbon atoms per molecule, and ethylene in a hydrocarbon-containing fluid in the presence of a catalyst composition to provide at least one product hydrocarbon isomer containing about four to about nine carbon atoms per molecule is provided. The at least one feed hydrocarbon can be selected from paraffins, isoparaffins, and the like and combinations thereof. The catalyst composition contains a hydrogen halide component, a sulfone component, and a metal halide component.
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- METHOD FOR THE PRODUCTION OF NON-AROMATIC HYDROCARBONS
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The invention relates to a method for the production of long-chain, branched-chain and/or cyclic hydrocarbons. A low molecular weight alkyl halide and a fused salt are firstly prepared. The fused salt contains an electrophilic compound and a reducing agent and is free from oxygen and oxygen compounds. The alkyl halide is then brought into contact with the fused salt such that long-chain, branched-chain and/or cyclic hydrocarbons are formed in the fused salt. The hydrocarbons formed in the fused salt are drawn off and can subsequently be separated from unreacted starting materials. By means of the above method, hydrogen can be produced during the reaction of the low molecular weight alkyl halide. The risk of oxidation of the alkane produced to give carbon monoxide or carbon dioxide is avoided by means of the reducing conditions in the fused salt. The product distribution can be controlled by means of suitable selection of the composition of the fused salt. Highly-branched hydrocarbons are produced with the preferred application of a sodium chloroaluminate fused salt.
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- Disproportionation of hydrocarbons
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A novel hydrocarbon disproportionation process is provided and includes contacting a hydrocarbon feed comprising at least one paraffin with a disproportionation catalyst comprising a support component, a metal, and a halogen in a disproportionation reaction zone under disproportionation reaction conditions.
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- C7+ paraffin isomerisation process and catalyst therefore
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There is provided a process for selective isomerisation of C4+ paraffins using a catalyst comprising mixed aluminium, tungsten and zirconium oxides, and a hydrogenation/dehydrogenation component, such as palladium or other Group VIII metals. The feed may optionally also include shorter paraffins, aromatics or cycloparaffins.
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- Alkene oligomerization process
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A process for oligomerising alkenes having from 3 to 6 carbon atoms which comprises contacting a feedstock comprising a) one or several alkenes having x carbon atoms, and, b) optionally, one or several alkenes having y carbon atoms, x and y being different, with a catalyst containing a zeolite of the MFS structure type, under conditions to obtain selectively oligomeric product containing predominant amounts of certain oligomers. The process is carried out at a temperature comprised between 125 and 175° C. when the feedstock contains only alkenes with 3 carbon atoms and between 140 and 240° C., preferably between 140 and 200° C. when the feedstock contains comprises at least one alkene with 4 or more carbon atoms.
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- Process of paraffin hydrocarbon isomerisation catalysed by an ionic liquid in the presence of a cyclic hydrocarbon additive
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A process for the conversion of linear and/or branched paraffins hydrocarbons, catalysed by an ionic liquid catalyst, in the presence of a cyclic hydrocarbon additive containing a tertiary carbon atom. The presence of the specific hydrocarbon additives influences the reaction mechanism by increasing the selectivity towards the formation of paraffin hydrocarbons with a higher degree of branching.
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- Reactions of aliphatic ketones R2CO (R = Me, Et, iPr, and tBu) with the MCl4/Li(Hg) system (M = U or Ti): Mechanistic analogies between the McMurry, Wittig, and Clemmensen reactions
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Analysis of the products of the reactions of ketones R2CO (R = Me, Et, iPr, tBu) with the MCl4/Li(Hg) system (M = U, Ti) at 20°C revealed significant differences. For R = Me, the reaction proceeded exclusively (M = U) or preferentially (M = Ti) via a metallopinacol intermediate resulting from dimerization of ketyl radicals. Pinacol was liberated by hydrolysis, and tetramethylethylene was obtained after further reduction at 65°C. For R = iPr, formation of iPr2C=CiPr2 as the only coupling product, the nonproduction of this alkene by reduction of the uranium pinacolate [U]-OCR2CR2O-[U] (R = iPr) at 20°C, and the instability of the corresponding titanium pinacolate towards rupture of the pinacolic C-C bond indicated that reductive coupling of iPr2CO did not proceed by dimerization of ketyl radicals. Formation of 2,4-dimethyl-2-pentene was in favor of a carbenoid intermediate resulting from deoxygenative reduction of the ketyl. These results revealed that for sterically hindered ketones, McMurry reactions can be viewed as Wittig-like olefination reactions. For R = tBu, no coupling product was obtained and the alkane tBu2CH2 was the major product. The involvement of the carbenoid species [M]=CtBu2 was confirmed by its trapping with H2O, leading to tBu2CH2, and with the aldehydes RCHO, giving the cross-coupling products tBu2C=C(R)H (R = Me, tBu). Therefore, in the case of severely congested ketones, McMurry reactions present strong similarities to the Clemmensen reduction of ketones, owing to the involvement in both reactions of carbenoid species which exhibit similar reactivity. Wiley-VCH Verlag GmbH, 2001.
- Villiers, Claude,Ephritikhine, Michel
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p. 3043 - 3051
(2007/10/03)
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- N-pentane isomerization in the presence of BCl3 containing superacids
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New superacid catalysts have been obtained by the action of BCl3 vapours on silicaalumina (87% SiO2). The mechanism and kinetics of pentane isomerization is discussed.
- Marczewski,Debowiak,Przerwa
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p. 2115 - 2126
(2007/10/03)
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- HYDROCONVERSION OF HEPTANE CATALYZED BY SULFIDED NiMo/HY ZEOLITES
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A series of catalysts made of Ni, Mo and NiMo sulfide encaged in HY zeolites (Si/Al = 3 to 17) were tested for the hydroconversion of heptane.The reaction was carried out at P(H2) = 8 MPa and with a constant supply of H2S.Propane and isobutane were the main products, but bimolecular cracking processes occurred to some extent.The yield of heptane isomers was low, showing a deficient hydrogenation function.The influence of the Si/Al ratio upon catalytic activity and selectivity was examined.
- Leglise, Jacques,Qotbi, Mohammed El,Cornet, Daniel
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p. 882 - 895
(2007/10/02)
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- Activite catalytique du superacide SbF5-HF lors de l'isomerisation de l'heptane
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The isomerization of n-heptane in the presence of the superacid SbF5-HF can be carried out by control of operating conditions.The rate-determining step of the isomerization of n-heptane is the intramolecular hydride-ion transfer, whereas it is the carbocation rearrangement in the case of the formation of the dimethyl-2,2-pentyle ion which is the forerunner of the cracking products.The rate constant of n-heptane isomerization is used to determine the influence of temperature, SbF5 concentration, hydrogen pressure, presence of benzene, on catalytic activity.This depends directly on the carbocations concentrations, especially high because of cracking, and on the nature, secondary or tertiary of these carbocations.
- Bassir, Mahbod,Torck, Bernard,Hellin, Michel
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p. 760 - 766
(2007/10/02)
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- CONTRIBUTION A L'ETUDE DES REACTIONS DE COMBINAISON DES RADICAUX ALCOYLE TERTIAIRES EN PHASE SOLIDE
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Disproportionation/combination ratios of self-reacting t-alkyl radicals are estimated in solid phase at low temperature.The low temperature solid state limit was estimated to be 7-25, this value is considerably lower than ratios of the literature (100 to 500) and is compatible with the FISCHER limit in liquid state.In the present work, the ratios are determined by product analysis from the gamma radiolysis of isobutane.
- Gourdin-Serveniere, C.,Fontaine, L. M.,Tilquin, B.
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p. 177 - 188
(2007/10/02)
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- EFFECTIVE GAS-PHASE DEOXYGENATION OF ALCOHOLS AND KETONES ON IRON CATALYST
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A method of gas-phase deoxygenation of alcohols and ketones into hydrocarbons on iron catalyst at 600 K and 1-2E5 Pa is dicussed.
- Glebov, L. S.,Mikaya, A. I.,Yatsenko, A. E.,Zaikin, V. G.,Kliger, G. A.,Loktev, S. M.
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p. 3373 - 3376
(2007/10/02)
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- L'isomerisation de radicaux insatures. II. Les radicaux α-ethallyles et α,γ-dimethallyles formes dans la photolyse de l'hexene-3 et du methyl-4-pentene-2 a 147,0 et 184,9 nm
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The photolysis of cis-3-hexene and 4-methyl-cis-2-pentene has been studied at 147.0 and 184.9 nm.The fragmentation pattern of the photoexcited molecule is normal: it requires, mainly , the split of a C-C bond located in the β position relative to the double bond (ca. 80percent).Some α(C-C), β(C-H), and α(C-H) primary splits complete this mechanism.The formation of α-ethallyl and α,γ-dimethallyl radicals is improtant in 3-hexene and 4-methyl-2-pentene, respectively.An isomerization process, involving these two radicals, is necessary to explaine the formation of part of the 1,3-pentadiene in the 3-hexene system and of all the 1,3-butadiene in the 4-methyl-2-pentene system.This process involves a 1,4-hydrogen atom transfer.
- Collin, Guy J.,Deslauriers, Helene
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p. 944 - 950
(2007/10/02)
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- Mecanisme de l'alkylation de l'isobutane par le propene sur zeolithe. I. Etudes preliminaires de la selectivite de la reaction
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Alkylation of isobutane by propylene has been studied at 70 and 80 deg C and 10 atm. of pressure over a cerium exchanged Y zeolite.Under these conditions large amounts of olefin are converted into adsorbed residues and C5-C9 isoalkanes (alkylate) are formed.Maximum alkylate yields are observed after 12 hours and become negligible after 24 hours.The main products result from alkylation, dimerization, self-alkylation and cracking reactions followed by hydride transfer.Catalyst poisonning is explained by the decrease of the zeolite cracking activity and dehydrogenation of the adsorbed species.
- Daage, Michel,Fajula, Francois
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p. 153 - 159
(2007/10/02)
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- Mecanisme de l'alkylation de l'isobutane par le propene sur zeolithe II. Etude des etapes elementaires de la reaction a l'aide de molecules marquees au carbone-13
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The mechanisms involved during the alkylation of isobutane by propene have been studied using carbon-13 labelled molecules.Several parallel reactions can lead to a same hydrocarbon.The carbon-13 distributions and structures of all the products can be explained by bimolecular processes between a limited number of species.These species are C3 and C4 olefins and ions and strongly adsorbed residues in which the tracer atoms lie in definite positions.
- Daage, Michel,Fajula, Francois
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p. 160 - 168
(2007/10/02)
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- Mechanism of Isomerization of Hydrocarbons on Metals. Part 10.-Isomerization and Dehydrocyclization of 2-Methyl(2-(13)C)hexane on a 10percent Pt-Al2O3 Catalyst
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The contact reactions of 2-methyl(2-(13)C)hexane and 2-methyl(6-(13)C)hexane have been investigated at 270 and 360 deg C, respectively, over a 10percent Pt-Al2O3 catalyst.The isomerizations of 2-methylhexane and 2,3-dimethylpentane, at 270 deg C, are very similar: the orders as a function of hydrogen are positive (0.2-1.75) and all the products are obtained by a one-step process according to either a bond-shift or a cyclic mechanism (the latter being predominant).The positive order, together with the absence of scrambling, is consistent with Frennet's model, assuming hydrocarbon adsorption on several contiguous metal sites.At 360 deg C, aromatization also takes place. 2-Methyl(6-(13)C)hexane yields hardly any methyllabelled toluene, showing that 1-6 and not 1-5 ring closure is the major mechanism of this reaction.
- Parayre, Patrick,Amir-Ebrahimi, Valia,Gault, Francois G.
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p. 1723 - 1734
(2007/10/02)
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