- Impact of the Spatial Organization of Bifunctional Metal–Zeolite Catalysts on the Hydroisomerization of Light Alkanes
-
Improving product selectivity by controlling the spatial organization of functional sites at the nanoscale is a critical challenge in bifunctional catalysis. We present a series of composite bifunctional catalysts consisting of one-dimensional zeolites (ZSM-22 and mordenite) and a γ-alumina binder, with platinum particles controllably deposited either on the alumina binder or inside the zeolite crystals. The hydroisomerization of n-heptane demonstrates that the catalysts with platinum particles on the binder, which separates platinum and acid sites at the nanoscale, leads to a higher yield of desired isomers than catalysts with platinum particles inside the zeolite crystals. Platinum particles within the zeolite crystals impose pronounced diffusion limitations on reaction intermediates, which leads to secondary cracking reactions, especially for catalysts with narrow micropores or large zeolite crystals. These findings extend the understanding of the ??intimacy criterion” for the rational design of bifunctional catalysts for the conversion of low-molecular-weight reactants.
- Cheng, Kang,Harmel, Justine,Oenema, Jogchum,Sunley, Glenn,Yoshida, Hideto,Ze?evi?, Jovana,Zhang, Zhaorong,de Jong, Krijn P.,van der Wal, Lars I.
-
supporting information
p. 3592 - 3600
(2020/02/05)
-
- Encapsulation of Crabtree's Catalyst in Sulfonated MIL-101(Cr): Enhancement of Stability and Selectivity between Competing Reaction Pathways by the MOF Chemical Microenvironment
-
Crabtree's catalyst was encapsulated inside the pores of the sulfonated MIL-101(Cr) metal–organic framework (MOF) by cation exchange. This hybrid catalyst is active for the heterogeneous hydrogenation of non-functionalized alkenes either in solution or in the gas phase. Moreover, encapsulation inside a well-defined hydrophilic microenvironment enhances catalyst stability and selectivity to hydrogenation over isomerization for substrates bearing ligating functionalities. Accordingly, the encapsulated catalyst significantly outperforms its homogeneous counterpart in the hydrogenation of olefinic alcohols in terms of overall conversion and selectivity, with the chemical microenvironment of the MOF host favouring one out of two competing reaction pathways.
- Grigoropoulos, Alexios,McKay, Alasdair I.,Katsoulidis, Alexandros P.,Davies, Robert P.,Haynes, Anthony,Brammer, Lee,Xiao, Jianliang,Weller, Andrew S.,Rosseinsky, Matthew J.
-
supporting information
p. 4532 - 4537
(2018/03/26)
-
- Synthesis and functionalization of ordered mesoporous carbons supported Pt nanoparticles for hydroconversion of n-heptane
-
A comprehensive study was performed on the spectroscopic and textural properties of ordered mesoporous carbon (OMC) of the CMK-3 type modified by acid oxidation using K2S2O8 as a benign oxidant and nitrogen-doping by the aid of the polymerization of ethylenediamine and carbon tetrachloride inside the pore channels of SBA-15 hard template. The pristine, nitrogen-doped, and oxidized-ordered mesoporous carbons were used as supports to prepare 10 wt% platinum nanoparticles-loaded catalysts using ethylene glycol as a reducing agent. The catalytic behavior, mechanism, and influence of the surface functionalization of the ordered mesoporous carbon bifunctional catalysts toward the hydroconversion of n-heptane using a fixed-bed flow system operated under atmospheric pressure were investigated. The synthesized samples were characterized by various analytical and spectroscopic techniques. The mesostructural regularity corresponding to the hexagonal P6mm symmetry of the OMC-CMK-3 type was well-reserved even after surface modifications replicated from an SBA-15 template. H2 pulse chemisorption and EDX mapping images confirmed differences in the Pt NPs contents and dispersion depending on the support composition. The catalytic activity results achieved were hand in hand with the proper balance between the acidity strength and Pt NPs dispersion degree.
- Said
-
p. 14517 - 14529
(2018/08/28)
-
- One-step hydroprocessing of fatty acids into renewable aromatic hydrocarbons over Ni/HZSM-5: Insights into the major reaction pathways
-
For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8-25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C6-C8 olefins over the catalysts' Br?nsted acid sites; these underwent Diels-Alder reactions on the catalysts' Lewis acid sites to form AHCs. C6-C8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Br?nsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.
- Xing, Shiyou,Lv, Pengmei,Wang, Jiayan,Fu, Junying,Fan, Pei,Yang, Lingmei,Yang, Gaixiu,Yuan, Zhenhong,Chen, Yong
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p. 2961 - 2973
(2017/02/05)
-
- PROCESS FOR SELECTIVE RING OPENING OF CYCLIC HYDROCARBONS
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PURPOSE: A process for ring opening is provided to obtain improved conversion ratio and selectivity in comparison with the case of using hydrogen as a reducing agent. CONSTITUTION: A cyclic hydrocarbon and a reducing agent are provided as supplying materials. The supplying materials are transferred into a reactor (5) and reacted under the presence of a catalyst. A product is separated from the effusion of reaction zone. The catalyst is a heterogeneous catalyst having both acid site and metallic component. The product is obtained by evaporating and heating a mixture containing 100 parts by weight of porous molecular sieve and 0.01-20 parts by weight of water soluble metallic salt. The cyclic hydrocarbon is a naphthene group cyclic hydrocarbon which is pentagonal or hexagonal compound, or an alkyl derivative thereof selected from cyclopentane and cyclohexane. The alkyl derivative is methyl, ethyl, profile, butyl, isopropyl or an isobutyl derivative.
- -
-
Paragraph 0078-0085
(2020/04/29)
-
- Hydrodeoxygenation of the angelica lactone dimer, a cellulose-based feedstock: Simple, high-yield synthesis of branched C7-C10 gasoline-like hydrocarbons
-
Dehydration of biomass-derived levulinic acid under solid acid catalysis and treatment of the resulting angelica lactone with catalytic K 2CO3 produces the angelica lactone dimer in excellent yield. This dimer serves as a novel feedstock for hydrodeoxygenation, which proceeds under relatively mild conditions with a combination of oxophilic metal and noble metal catalysts to yield branched C7-C10 hydrocarbons in the gasoline volatility range. Considering that levulinic acid is available in >80 % conversion from raw biomass, a field-to-tank yield of drop-in, cellulosic gasoline of >60 % is possible. Fuel for thought: Biomass-derived levulinic acid can be converted in three simple steps via the angelica lactone dimer into branched, gasoline-range hydrocarbons in high yield by using a combination of oxophilic metal and noble metal catalysts (see scheme). Copyright
- Mascal, Mark,Dutta, Saikat,Gandarias, Inaki
-
supporting information
p. 1854 - 1857
(2014/03/21)
-
- Influence of chlorine on the catalytic properties of supported rhodium, iridium and platinum in ring opening of naphthenes
-
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
-
p. 207 - 219
(2013/07/26)
-
- C5-C7 linear alkane hydroisomerization over MoO 3-ZrO2 and Pt/MoO3-ZrO2 catalysts
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The catalytic activity of MoO3-ZrO2 and Pt/MoO 3-ZrO2 has been assessed based on the C5-C 7 linear alkane hydroisomerization in a microcatalytic pulse reactor at 323-623 K. The introduction of Pt altered the crystallinity and acidity of MoO3-ZrO2. The catalytic activity of Pt/MoO 3-ZrO2 was inferior than that of MoO3-ZrO 2, although the Pt/MoO3-ZrO2 performed higher hydrogen uptake capacity. IR and ESR studies confirmed the heating of MoO 3-ZrO2 in the presence of hydrogen formed active protonic acid sites and electrons which led to change in the Mo oxidation state. Similar phenomenon was observed for Pt/MoO3-ZrO2 at ≤323 K. Contrarily, heating of Pt/MoO3-ZrO2 in the presence of hydrogen at higher temperature did not form protonic acid sites but intensified Lewis acidic sites. It is suggested that Pt facilitates in the interaction of spiltover hydrogen atom and MoO3 to form MoO2 or Mo 2O5 over ZrO2 support which may be intensified the Lewis acidic sites.
- Triwahyono,Jalil,Ruslan,Setiabudi,Kamarudin
-
-
- Ring opening of decalin and methylcyclohexane over bifunctional Ir/WO 3/Al2O3 catalysts
-
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
-
-
- Modification of the catalytic properties of MoO2-x(OH) y dispersed on TiO2 by Pt and Cs additives
-
Addition of 5% Pt or alkali metals such as K or Cs each separately to the bifunctional MoO2-x(OH)y catalyst results in modification of the chemical structure of this system, especially in the case of alkali metals. A new MoO2-x(OA)y, AK, Cs, monofunctional structure having only metallic properties is formed. In the case of Cs for example, the MoOCs bond formation takes place in the course of the reduction process of MoO3 to MoO2 by hydrogen hinders the acidic Br?nsted MoOH formation, which usually is formed in this system. Characterization by surface XPS-UPS, ISS and FT-IR spectroscopic techniques as well as catalytic activity carried out at the same experimental conditions confirm the presence of this monofunctional MoO2-x(OCs)y system. On the contrary, platinum addition enhances the metallic character of the MoO2-x(OH)y bifunctional system in terms of slight improvement in the conversion of 1-heptene and n-heptane as well as dehydrogenation of methylcyclohexane to toluene.
- Al-Kandari,Mohamed,Al-Kharafi,Zaki,Katrib
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experimental part
p. 298 - 305
(2012/05/20)
-
- Hydroisomerization of saturated hydrocarbons with novel MCM-41 immobilized Re(V) complex catalysts
-
The hetero-functionalized phosphines HPN2, H2PNO and HPN-Pip containing tricarbonyl Re(V) complexes, i.e. [Re(CO)3(κ 3-PN2)] (I), [Re(CO)3Br(κ2- H2PNO)] (II) and [Re(CO)3Br(κ2-HPN-Pip)] (III) were covalently bonded to modified and MCM-41 to obtain novel supported hybrid catalysts. Remarkable high catalytic effects were observed with these catalysts in the hydroisomerization of n-alkanes at low temperature. The catalyst II/MCM-41 provided the highest TONs 3.32 × 103 with 37% yield for n-hexane and 3.18 × 103 with 30% yield for n-heptane. Under optimized condition, good selectivities for n-hexane (85%) and for n-heptane (91%) were obtained. The TGA was used to evaluate the stability of catalysts and reusable for several cycles. A possible carbenium-based mechanism been used to explain product formation.
- Mishra, Gopal S.,Kumar, Anil
-
experimental part
p. 1 - 8
(2012/08/08)
-
- Ring opening of decalin and methylcyclohexane over alumina-based monofunctional WO3/Al2O3 and Ir/Al 2O3 catalysts
-
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
-
scheme or table
p. 62 - 77
(2012/03/11)
-
- Conversion of biomass-derived butanal into gasoline-range branched hydrocarbon over Pd-supported catalysts
-
For production of gasoline-range branched hydrocarbon from butanal, Pd catalysts supported on different metal oxides were applied. Among the prepared catalysts, Pd/ZrO2 showed the complete butanal conversion with the formation of C7-to-C9 branched hydrocarbon (75% yield). Additionally, the ratios of O/C and straight-chain to branched hydrocarbon (n-C/br-C) were found to be 0.005 and 0.17, respectively. This indicates that an adequate combination of Pd dispersion and amphoteric ZrO2 character promoted hydrodeoxygenation, C-C coupling and isomerization reactions. Consequently, both Pd dispersion and acid-base properties of supports are suggested to play a pivotal role in producing gasoline-range hydrocarbon at a high yield.
- Kim, Sung Min,Lee, Mi Eun,Choi, Jae-Wook,Suh, Dong Jin,Suh, Young-Woong
-
scheme or table
p. 108 - 113
(2012/03/10)
-
- PROCESS FOR THE PRODUCTION OF A HYDROCARBON
-
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.
- -
-
Page/Page column 27-28
(2009/06/27)
-
- Selective methylative homologation: An alternate route to alkane upgrading
-
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.
-
scheme or table
p. 11988 - 11995
(2009/02/05)
-
- Production of high purity cumene from non-extracted feed and hydrocarbon composition useful therein
-
A process for producing an cumene product having a purity of at least 99.50 percent based on the weight of cumene present in the product by the propylation of the benzene present in non-extracted hydrocarbon composition feed, e.g., non-extracted reformate. The non-extracted hydrocarbon composition feed is substantially free of both C4? hydrocarbons and the C7+ aromatic hydrocarbons and contains benzene and benzene coboilers. The process is carried out in the liquid phase, in the presence of an acid-active catalyst containing MCM-22 family molecular sieve, and under specified conditions.
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Page/Page column 11
(2008/12/07)
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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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- 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
-
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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p. 159 - 171
(2008/09/21)
-
- Isomerization of N-heptane in naphtha cuts
-
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)
-
- Alkylation process with recontacting in settler
-
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)
-
- The transformations of toluene on alumina and bifunctional catalysts
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The activity of Pt, Rh, and Ni catalysts deposited on Al2O 3 and tungsten-containing catalysts 20% H4SiW 12O40/ZrO2 and 15% WOx/ZrO 2 in the hydrogenation of toluene and toluene ring opening and isomerization in the presence of hydrogen was studied. Under experimental conditions (160-360°C, 2.2 MPa), the main reactions on Rh/Al 2O3 were the hydrogenation of toluene into methylcyclohexane, hydrogenolysis into isoheptanes, and hydrocracking into alkanes C1-C6. On Pt, Rh, and Ni catalysts on carriers with strong acid properties, the isomerization of the six-membered into five-membered ring followed by hydrogenolysis (hydrocracking) of alkylcyclopentanes occurred. The yield of heptane isomers, however, did not exceed 13%. The activity of Pt and Rh catalysts on a high-acidity carrier (WOx/ZrO2) in hydrocracking was much higher than that of catalysts based on deposited heteropoly acid. The yields of hydrogenolysis (hydrocracking) products on Ni/WOx/ZrO2 were much lower than on Pt(Rh)/WOx/ZrO2. The highest yield of ring opening products (isoheptanes and n-heptane) was obtained with layered loading of two catalysts; it reached 58 wt % at 300°C and a 2.2 MPa pressure, which was 4.5 and 2 times higher than the yield obtained on Ni-Pt/WOx/ZrO 2 and 2% Rh/Al2O3 catalysts. Hydrodemethylation was not the main direction of toluene transformations on any of the catalysts studied. Pleiades Publishing, Inc., 2006.
- Masloboishchikova,Khelkovskaya-Sergeeva,Bogdan,Vasina,Kustov
-
p. 551 - 556
(2007/10/03)
-
- Silica-supported dendrimer-palladium complex-catalyzed selective hydrogenation of dienes to monoolefins
-
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
-
p. 725 - 731
(2007/10/03)
-
- ESTER SYNTHESIS
-
Process for making lower aliphatic ester, especially ethyl acetate, by reacting a lower olefin with a saturated lower aliphatic mono-carboxylic acid in the vapor phase using a heteropolyacid catalyst, wherein the reaction pressure is 11 to 20 barg (1100 to 2000 KPa), more preferably 12 to 15 barg (1200 to 1500 KPa). The reaction temperature is 140 to 250°C, more preferably 160 to 195°C. The process reduces the level of by-products, for example methyl ethyl ketone and/or acetaldehyde.
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-
Page/Page column 8-11
(2008/06/13)
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- SYSTEM AND METHOD FOR PURIFYING HEPTANE
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Removing impurities from a heptane stream by contacting the heptane stream with an acidic catalyst, wherein the contacting reduces a concentration of one or more close boiling impurities, one or more olefins, or both. The impurities are isomerized via contact with the acidic catalyst into species that possess lower octane levels or that do not possess boiling points as near to the boiling point of n-heptane, which promotes separation of the impurities via distillation. Close boiling impurities may include such compounds as cis-1,2-dimethylcyclopentane and methylcyclohexane or may be compounds having boiling points at a standard pressure of 760 Torr in the range of about 96.5 to about 100.5 degrees Celsius including such compounds as cis-1,2-dimethylcyclopentane and methylcyclohexane. The concentration of cis-1,2-dimethylcyclopentane and methylcyclohexane may be reduced by at least about 25 and 10 percent by weight, respectively. The concentration of olefins, as measured by the Bromine Index, may be reduced by at least about 25 percent by weight.
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-
Page/Page column 26-31
(2008/06/13)
-
- 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.
- -
-
-
- Catalyst and process for contacting a hydrocarbon and ethylene
-
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.
- -
-
-
- Process of paraffin hydrocarbon isomerisation catalysed by an ionic liquid in the presence of a cyclic hydrocarbon addditive
-
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.
- -
-
-
- C7+ paraffin isomerisation process and catalyst therefore
-
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.
- -
-
-
- Pentane transformation over silicaalumina/BCl3 solid superacid
-
Pentane transformation over SiO2(87%) - Al2O3/BCl3 superacid was studied. It was found that Broensted superacid centres formed in the reaction between the carrier and BCl3 vapours are active in n-pentane low temperature transformation. Pentane is converted over them into carbenium ion (through intermediate carbonium ion), which either undergoes isomerization to form 2-methylbutane or reacts with a second molecule of the reactant forming 2-methylpropane and a longer surface carbenium ion. The latter acts as a secondary active centre for 2-methylpropane formation and also undergoes further transformation leading finally to coke.
- Marczewski,Debowiak,Marczewska
-
p. 737 - 747
(2007/10/03)
-
- H2-reduction of Pt/MoO3 to MoOx with a large surface area and its catalytic activities for the conversions of heptane and propan-2-ol
-
The relationship between the surface area of H2-reduced Pt/MoO3 and the extent of reduction was studied. The surface areas of H2-reduced MoO3 and Pt/MoO3 varied significantly with reduction temperature and period. The largest surface area was obtained at a reduction degree of 60-70%. The distribution of isomerization products was independent of the reduction degree. Heptane was isomerized to 2-and 3-methylhexane in equal amounts. The isomerization selectivity decreased slightly with increasing conversion level, but the high selectivity was preserved even at high conversion levels on the catalysts. The catalytic behavior of H2-reduced MoO3 and Pt/MoO3 in the isomerization of heptane seemed to be different from that in the conversion of 2-propanol.
- Matsuda,Uchijima,Sakagami,Takahashi
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p. 4430 - 4436
(2007/10/03)
-
- Catalytic properties of H2-reduced MoO3 with noble metal for the conversions of heptane and propan-2-ol
-
Effects of H2 reduction on the catalytic properties of MoO3 with Pt, Pd, Rh, Ir, or Ru for the conversions of heptane and propan-2-ol were studied. The catalytic activity of MoO3 with noble metal for the isomerization of heptane was strongly dependent on the period of H2 reduction at 623 K. This behavior was almost the same as that of MoO3 without noble metal. Among the catalysts tested, Pt/MoO3 was the most active for this reaction. The catalytic activities of MoO3 for dehydration and dehydrogenation of propan-2-o1 also increased in proportion with the period of H2 reduction. In the case of MoO3 with noble metal, a higher dehydration activity was obtained by a longer period of H2 reduction, while the dehydrogenation activity was almost independent of the reduction period. Pt/MoO3 exhibited a high dehydration activity compared with the other catalysts, indicating the most acidic property of Pt/MoO3. We conclude from these results that the high isomerization activity of Pt/MoO3 can be attributed to its high acidity as well as to the hydrogenative and dehydrogenative properties of Pt metal.
- Uchijima, Fumiko,Takagi, Tomoaki,Itoh, Hidenobu,Matsuda, Takeshi,Takahashi, Nobuo
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p. 1077 - 1083
(2007/10/03)
-
- 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
-
p. 2115 - 2126
(2007/10/03)
-
- Effect of alumina fluoridation on hydroconversion of n-heptane on sulfided NiW/Al2O3 catalysts
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Hydroisomerization and hydrocracking of n-heptane on sulfided NiW catalysts, supported on alumina modified with various amounts of fluoride, have been studied at 673, 698, and 723 K and at a total pressure of 3 MPa. It was found that alumina fluoridation increases the catalytic activity for both hydroisomerization and hydrocracking and provides a higher hydroisomerization selectivity. Differences in product selectivities for the hydroisomerization and hydrocracking of n-heptane indicate that alumina fluoridation induces also changes in the various contributions of the mechanisms involved in the transformation of n-heptane. A decrease in the ratio of 3-MC6 and 2-MC6 monobranched isomers predicted by a branching mechanism via the protonated cyclopropane (PCP) intermediates and a decrease in the dimerization cracking mechanism in favor of the classic bifunctional cracking mechanism were observed with increasing fluoride content. Theses changes are results of a better balance of the (de)hydrogenation and acidity functions of the sulfided catalysts with increasing fluoride content since the incorporation of fluoride increases the (de)hydrogenation function and decreases the strength of the acid sites.
- Benitez,Ramirez,Cruz-Reyes,Lopez Agudo
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p. 137 - 145
(2007/10/03)
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- Isomerization of heptane on molybdenum oxide catalysts with a small amount of nickel
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The catalytic performances of molybdenum oxides for the isomerization of heptane have been investigated at 623 K under atmospheric pressure. After a long induction period, MoO3 became an active and selective catalyst for this reaction. The catalytic activity, however, declined gradually with time on stream. Loading small amounts of Ni onto MoO3 was effective in stabilizing the isomerization activity without a change in isomerization selectivity. The isomerization activity became stable against deactivation when Ni/SiO2 was mixed with MoO3. We conclude from these results that Ni acted as a port of spilled-over hydrogen, which stabilized the isomerization activity of MoO3.
- Matsuda, Takeshi,Sakagami, Hirotoshi,Takahashi, Nobuo
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p. 2225 - 2229
(2007/10/03)
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- Catalytic properties of Ni-MoO3 for the isomerization of heptane
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The catalytic properties of Ni-MoO3 for the isomerization of heptane were investigated. After treatment with a mixture of H2 and heptane, Ni-MoO3 catalysts became active and selective for this reaction. The isomerization activity increased with increasing amount of Ni loading onto MoO3, indicating that Ni was an effective additive to enhance the catalytic performances of MoO3 for the isomerizalion of heptane.
- Matsuda, Takeshi,Niwayama, Takamitsu,Sakagami, Hirotoshi,Takahashi, Nobuo
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p. 373 - 374
(2007/10/03)
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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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- 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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p. 141 - 147
(2007/10/03)
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- Ring-Opening Hydrogenation Reactions of Monoalkyl-Substituted Cyclobutanes over Ni/SiO2 Catalyst
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The hydrogenative ring-opening reactions of methyl- and propylcyclobutane were studied over Ni/SiO2 catalyst in wide temperature and hydrogen pressure ranges, Firstly, the temperature dependence of ring opening was determined and maximum curves were observed for both reactants.On the basis of temperature dependence curves, various temperature were selected for hydrogen pressure studies.At both 523 and 573 K, only hydrogenative ring opening occurred, and the ring opened mostly in the sterically less hindered direction in the case of methylcyclobutane over clean as well as working catalysts.However, for propylcyclobutane the selectivity was close to statistical or opposite to that for methylcyclobutane, especially at lower hydrogen pressures over the initial catalyst.At the lowest temperature at which ring opening occurred at all, exclusive heptane formation (ring opening in the more hindered direction) was observed.The hydrogen pressure dependence curves over the initial and working catalysts were used to draw mechanistic inferences concerning the ring-opening reactions.
- Toeroek, Bela,Bartok, Mihaly
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p. 315 - 322
(2007/10/02)
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- The Energy-Well of Diradicals, IV. - 2-Methylene-1,4-cyclohexadiyl
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The energy surface of the title compound 2 is derived from the kinetics of its precursors 5, 6, 7, and 8, the oxygen dependance of its trapping rate, and heat of hydrogenation measurements of 5, 6, 7, and 15.These data lead to a heat of formation of the diradical 2 of 69.8 kcal/mol and an energy well of 8.2 kcal mol-1.From the Curie plot of the ESR spectrum and oxygen trapping experiments a singlet-triplet splitting of 1.4 kcal mol-1 is indicated, with the triplet being the ground state. - Key Words: Diradical / Oxygen trapping / Heat of formation / Energy well / ESR spectrum / Singlet-triplet splitting / Cope rearrangement, nonconcerted
- Roth, Wolfgang R.,Wollweber, Detlef,Offerhaus, Rolf,Rekowski, Volker,Lennartz, Hans-Werner,et al.
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p. 2701 - 2716
(2007/10/02)
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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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- HYDROGENOLYSIS OF DICHLORO- AND DIBROMOALKANES
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Dichloroalkanes and dibromoalkanes with various structures are reduced to the saturated hydrocarbons with yields of 70-90percent by the action of triethylsilane in the presence of catalytic amounts of aluminum chloride.
- Parnes, Z. N.,Romanova, V. S.,Vol'pin, M. E.
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p. 254 - 257
(2007/10/02)
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- Comments on the Mechanism of MTG/HZSM-5 Conversion
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A comparative F.t.i.r./g.c.-m.s. study of MTG conversion on a series of progressively dealuminated HZSM-5 and H-mordenite surfaces reveals the role of zeolite dealumination in modifying the zeolite pore void (i.e. catalytic volume) and therefore shape-selectivity.This is illustrated by aa different distribution of the primary alkenes formed under similar experimental conditions.G.c-m.s. analysis of a reaction at the early stages of dimethylether conversion reveals that ethene, which forms in trace quantities on HZSM-5, is dominant on H-mordenite.The propene/butenes ratio is high (c.a. 1.7) for H-mordenite, but is 1.0 and decreased with increased dealuminatiom for HZSM-5.Isobutene dominates for increasingly dealuminated HZSM-5.Methanol reformation proceeds concurrently with alkene formation, suggesting a route involving either propagation and/or decomposition to alkenes.The mechanistic implications of the interdependence of zeolite dealumination, modified pore void and identifi of alkenes are analysed.
- Sayed, Moein B.
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p. 1771 - 1778
(2007/10/02)
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- ALKANE DEHYDROCYCLIZATION AND ALKYLCYCLOPENTANE CONVERSIONS AT 13.8 bar (200 psi) WITH Pt-Al2O3 CATALYSTS
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The selectivity, defined as aromatics/isoalkanes, for the formation of aromatics is greater for the conversion of n-alkanes than for the conversion of alkylcyclopentanes with a platinum nonacidic alumina catalyst.Alkylcyclopentanes undergo hydrogenolysis to isoalkanes with the same carbon number at least ten to twenty times faster than they react to form aromatics over this catalyst.The results do not support an aromatization mechanism that includes the formation of five carbon ring intermediates.
- Hardy, Rita H.,Davis, Burtron H.
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p. 269 - 278
(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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- CYCLIZATION OF C7-ALKANES OVER Pt BLACK CATALYST
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C6-and C5-cyclization of heptane isomers (and also, olefin formation as a related process) over Pt-black have been studied in pulse and circulation systems.Hydrogendeficient conditions favour aromatization, via presumably terminal olefins.C5-Cyclization in the presence of more hydrogen is accompanied by internal olefin formation.Relative reactivities of all heptane isomers have been measured; this shows that cyclization is easier between terminal methyl groups.Optimum hydrogen pressures for both types of cyclization have been determined (and compared with hydrogenolysis, too).Earlier mechanism suggestion for aromatization and cyclopentane formation have been confirmed; the distinction between two types of bond shift mechanisms producing aromatics (from substituted pentanes) and saturated isomers, respectively, has recieved additional support facilitating the identification of these two reactions with mechanisms proposed in the literature.
- Zimmer, H.,Paal, Z.,Tetenyi, P.
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p. 513 - 532
(2007/10/02)
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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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p. 1704 - 1722
(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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