464-06-2Relevant academic research and scientific papers
Impact of the Spatial Organization of Bifunctional Metal–Zeolite Catalysts on the Hydroisomerization of Light Alkanes
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)
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.
Preparation method of branched alkane (by machine translation)
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Paragraph 0040; 0043-0047, (2020/01/08)
The preparation method of the branched alkane disclosed by the invention comprises, the following steps: under. a protective atmosphere condition, mixing the alkyl alcohol intermediate with an: alkyl metal reagent and an, organic solvent, to obtain the branched alkane, and the method disclosed by, the invention is; simple in synthesis route, high in yield and, high in, purity. (by machine translation)
GAS-TO-LIQUID REACTOR AND METHOD OF USING
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Paragraph 0140-0142, (2019/08/15)
A device and a process to propagate molecular growth of hydrocarbons, either straight or branched chain structures, that naturally occur in the gas phase to a molecular size sufficient to shift the natural occurring phase to a liquid or solid state is provided. According to one embodiment, the device includes a grounded reactor vessel having a gas inlet, a liquid outlet, and an electrode within the vessel; a power supply coupled to the electrode for creating an elecirostatic field within the vessel for converting the gas to a liquid and or solid state.
Conversion of dimethyl ether to 2,2,3-trimethylbutane over a Cu/BEA catalyst: Role of Cu sites in hydrogen incorporation
Schaidle, Joshua A.,Ruddy, Daniel A.,Habas, Susan E.,Pan, Ming,Zhang, Guanghui,Miller, Jeffrey T.,Hensley, Jesse E.
, p. 1794 - 1803 (2015/03/14)
Recently, it has been demonstrated that methanol and/or dimethyl ether can be converted into branched alkanes at low temperatures and pressures over large-pore acidic zeolites such as H-BEA. This process achieves high selectivity to branched C4 (e.g., isobutane) and C7 (e.g., 2,2,3-trimethylbutane) hydrocarbons. However, the direct homologation of methanol or dimethyl ether into alkanes and water is hydrogen-deficient, resulting in the formation of unsaturated alkylated aromatic residues, which reduce yield and can contribute to catalyst deactivation. In this paper we describe a Cu-modified H-BEA catalyst that is able to incorporate hydrogen from gas-phase H2 cofed with dimethyl ether into the desired branched alkane products while maintaining the high C4 and C7 carbon selectivity of the parent H-BEA. This hydrogen incorporation is achieved through the combination of metallic Cu nanoparticles present on the external surface of the zeolite, which perform H2 activation and olefin hydrogenation, and Lewis acidic ion-exchanged cationic Cu present within the H-BEA pores, which promotes hydrogen transfer. With cofed H2, this multifunctional catalyst achieved a 2-fold increase in hydrocarbon productivity in comparison to H-BEA and shifted selectivity toward products favored by the olefin catalytic cycle over the aromatic catalytic cycle.
Synthesis and hydrogenation activity of iron dialkyl complexes with chiral bidentate phosphines
Hoyt, Jordan M.,Shevlin, Michael,Margulieux, Grant W.,Krska, Shane W.,Tudge, Matthew T.,Chirik, Paul J.
, p. 5781 - 5790 (2015/02/19)
The activity of bis(phosphine) iron dialkyl complexes for the asymmetric hydrogenation of alkenes has been evaluated. High-throughput experimentation was used to identify suitable iron-phosphine combinations using the displacement of pyridine from py2Fe(CH2SiMe3)2 for precatalyst formation. Preparative-scale synthesis of a family of bis(phosphine) iron dialkyl complexes was also achieved using both ligand substitution and salt metathesis methods. Each of the isolated organometallic iron complexes was established as a tetrahedral and hence high-spin ferrous compound, as determined by M?ssbauer spectroscopy, magnetic measurements, and, in many cases, X-ray diffraction. One example containing a Josiphos-type ligand, (SL-J212-1)Fe(CH2SiMe3)2, proved more active than other isolated iron dialkyl precatalysts. Filtration experiments and the lack of observed enantioselectivity support dissociation of the phosphine ligand upon activation with dihydrogen and formation of catalytically active heterogeneous iron. The larger six-membered chelate is believed to reduce the coordination affinity of the phosphine for the iron center, enabling metal particle formation.
Mechanistic details of acid-catalyzed reactions and their role in the selective synthesis of triptane and isobutane from dimethyl ether
Simonetti, Dante A.,Ahn, John H.,Iglesia, Enrique
experimental part, p. 173 - 195 (2011/03/17)
We report here kinetic and isotopic evidence for the elementary steps involved in dimethyl ether (DME) homologation and for their role in the preferential synthesis of 2,2,3-trimethylbutane (triptane) and isobutane. Rates of methylation of alkenes and of hydrogen transfer, isomerization and β-scission reactions of the corresponding alkoxides formed along the homologation path to triptane were measured using mixtures of 13C-labeled dimethyl ether (13C-DME) and unlabeled alkenes on H-BEA. DME-derived C1 species react with these alkenes to form linear butyls from propene, isopentyls from n-butenes, 2,3-dimethylbutyls from isopentenes, and triptyls from 2,3-dimethylbutenes; these kinetic preferences reflect the selective formation of the more highly substituted carbenium ions and the retention of a four-carbon backbone along the path to triptane. Hydrogen transfer reactions terminate chains as alkanes; chain termination probabilities are low for species along the preferred methylation path, but reach a maximum at triptyl species, because tertiary carbenium ions involved in hydrogen transfer are much more stable than those with primary character required for triptene methylation. Alkenes and alkanes act as hydrogen donors and form unsaturated species as precursors to hexamethylbenzene, which forms to provide the hydrogen required for the DME-to-alkanes stoichiometry. Weak allylic C-H bonds in isoalkenes are particularly effective hydrogen donors, as shown by the higher termination probabilities and 12C content in hexamethylbenzene as 12C-2-methyl-2-butene and 12C-2,3-dimethyl-2-butene pressures increased in mixtures with 13C-DME. The resulting dienes and trienes can then undergo Diels-Alder cyclizations to form arenes as stable by-products. Isomerization and β-scission reactions of the alkoxides preferentially formed in methylation of alkenes are much slower than hydrogen transfer or methylation rates, thus preventing molecular disruptions along the path to triptane. Methylation at less preferred positions leads to species with lower termination probabilities, which tend to grow to C8+ molecules; these larger alkoxides undergo facile β-scission to form tert-butoxides that desorb preferentially as isobutane via hydrogen transfer; such pathways resolve methylation "missteps" by recycling the carbon atoms in such chains to the early stages of the homologation chain and account for the prevalence of isobutane among DME homologation products. These findings were motivated by an inquiry into the products formed via C1 homologation, but they provide rigorous insights about how the structure and stability of carbenium ions specifically influence the rates of methylation, hydrogen transfer, β-scission, and isomerization reactions catalyzed by solid acids.
PROCESS FOR THE PRODUCTION OF A HYDROCARBON
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Page/Page column 21-23, (2009/06/27)
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.
Selective methylative homologation: An alternate route to alkane upgrading
Bercaw, John E.,Hazari, Nilay,Labinger, Jay A.,Scott, Valerie J.,Sunley, Glenn J.
scheme or table, p. 11988 - 11995 (2009/02/05)
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.
Hydrocarbon separation
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Page/Page column 11, (2008/12/06)
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.
