- High-Temperature Stabilities of Hydrocarbons
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A chemical thermodynamic analysis of hydrocarbon molecules from 1500 to 3000 K is presented for species C2nH2m, n=1-21, m=1-8.With group additivity as the primary estimation method, the nature and chemical thermodynamic properties of the most stable molecules ( stabilomers ) are found.Concentrations of these molecules are then examined in equilibrium with acetylene and molecular hydrogen after taking into account numbers of isomers.Thermodynamically favored pathways leading to large, condensed polyaromatic species are examined in detail.Two general types of paths are found.At higher H2/C2H2 ratios (>=1), most species on these paths are polycyclic aromatic molecules and, depending on partial pressures of C2H2 and H2, a free energy barrier appears in the range 1400-1800 K which increases sharply with increasing temperature.At lower H2/C2H2 ratios, many smaller species are cyclic, and as this ratio becomes smaller the barrier declines and becomes less sensitive to temperature.A brief dicussion of the connection between these results and the kinetics of carbon polymerization is then presented.
- Stein, S. E.,Fahr, A.
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- Ion-molecule reactions of ArN2+ with simple aliphatic hydrocarbons at thermal energy
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The product ion distributions and rate constants are determined for ion-molecule reactions of ArN2+ with C2Hn (n=2,4,6) and C3Hn (n=6,8) by using a thermal ion-beam apparatus.Although charge-transfer channels leading to parent ions and/or fragment ions are found, no displacement reaction leading to ArCmHn+ and N2CmHn+ is detected.A comparison of the product ion distributions with breakdown patterns of the parent ions suggests that fragment ions, formed through cleavage of C-H and/or C-C bonds, are produced via near-resonant ionic states in the 13.1-13.4 eV range.The branching ratios of parent ions for C2H4 (68percent) and C3H6 (20percent) are larger than those for C2H6 (5percent) and C3H8 (5percent).The large branching ratios of the parent ions for the unsaturated hydrocarbons are explained as due to a strong interaction of a vacant orbital of ArN2+ with the highest occupied ?C=C orbital of the unsaturated hydrocarbons which induces nonresonant charge transfer.The total rate constant for C2H2 is 6.8x10-10 cm3 s-1, while those for C2Hn (n = 4,6) and C3Hn (n = 6,8) are in the range (8.5-9.8)x10-10 cm3 s-1.The former and the latter values correspond to 69percent and 77percent-90percent of the calculated values from Langevin or average dipole orientation (ADO) theory.The smaller kobs/kcalc ratio for C2H2 is attributed to the lack of near-resonant ionic states with favorable Franck-Condon factors for ionization.
- Tsuji, Masaharu,Matsumura, Ken-ichi,Kouno, Hiroyuki,Aizawa, Masato,Nishimura, Yukio
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- Reactions of vinyl radicals at high temperatures: Pyrolysis of vinyl bromide iodide and the reaction H + C2D2 → D + C2HD
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Five sets of experiments were carried out to determine the rate constant for dissociation of C2H3 at high temperatures. In all cases the measurements involved absorption of H or D Lyman-α radiation in argon-diluted gas mixtures reacting behind shock waves. For pyrolysis of vinyl bromide at 0.5-atm total pressure we found for C2H3 + Ar → C2H2 + H + Ar, k = 7.0 × 1013 exp(-28 kcal/RT) mol-1 cm3 s-1 at 1380-1750 K. For the same reaction initiated from vinyl iodide at 0.5-atm total pressure and 1060-1370 K, we found k = 3.5 × 1014 exp(-33 kcal/RT) mol-1 cm3 s-1. In three sets of experiments in which H atoms reacted with C2D2 to produce D atoms, we obtained values of k∞ for the reaction H + C2H2 → C2H3 of 8 × 1011, 1.2 × 1012, and 3.4 × 1012 mol-1 cm3 s-1 in the temperature range 1200-1900 K, with no clearly visible temperature dependence. All of the experimental values lie 3-10 times lower than those deduced from earlier work at high temperatures or based on ab initio calculations for the vinyl radical.
- Rao,Skinner, Gordon B.
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- The Dewar Isomer of 1,2-Dihydro-1,2-azaborinines: Isolation, Fragmentation, and Energy Storage
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The photochemistry of 1,2-dihydro-1,2-azaborinine derivatives was studied under matrix isolation conditions and in solution. Photoisomerization occurs exclusively to the Dewar valence isomers upon irradiation with UV light (>280 nm) with high quantum yiel
- Edel, Klara,Yang, Xinyu,Ishibashi, Jacob S. A.,Lamm, Ashley N.,Maichle-M?ssmer, C?cilia,Giustra, Zachary X.,Liu, Shih-Yuan,Bettinger, Holger F.
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- Reactions of ethynyl radicals. Rate constants with CH4, C2H6, and C2D6
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The rate constants for the abstraction of H atoms from CH4, C2H6, and D atoms from C2D6 by C2H (ethynyl) radicals have been determined by using a flash photolysis-kinetic spectroscopic technique. The values obtained, at 297 K, are (1.2 ± 0.2) × 10-12, (6.5 ± 0.4) × 10-12, and (3.1 ± 0.5) × 10-12 cm3 molecule-1 s-1, respectively. The rate constants are independent of added helium over the pressure range 20-700 torr. The kinetic parameters were determined by monitoring the acetylene product spectroscopically using C2H-CF3 as the source of ethynyl radicals.
- Laufer, Allan H.
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- Thermal Decomposition of Energetic Materials. 25. Shifting of the Dominant Decomposition Site by Backbone Substitution of Alkylammonium Nitrate Salts
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Exchanging X = -C(NO2)2F for X = -C(NO2)3 causes the dominating fast thermal decomposition site in NO3 salts to shift from largely that of the C-NO2 bond to largely that of the -H+...NO3- portion.This is consistent with an order of thermal stability of the energetic sites in these salts of -C(NO2)2F>-H+...NO3->-C(NO2)3.These conclusions were drawn from the nature of the IR-active gas products that are evolved in real time upon fast thermolysis (>100 K s-1) and from slow heating of the condensed phase.The O/H ratio of the parent primary ammonium salt appears to be a qualitative indicator of whether NH3(g) will formed under these conditions.Salts with O/H >/= 1 have not been observed to release NH3(g) while those with O/H 1 do.The salt with X=-C(NO2)2F possesses four polymorphs between 297 K and its two melting points.Only two polymorphs are present when X = -C(NO2)3.
- Oyumi, Y.,Brill, T. B.
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- Dehydrochlorination of 1,2-dichloroethane over Ba-modified Al2O3 catalysts
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Bimodal mesoporous alumina (Al2O3) was prepared using polyethyleneglycol (PEG 20,000) and cetyl trimethyl ammonium bromide as a template. The incorporation of Ba with various loadings was carried out by incipient wetness. Characterization was performed by XRD, N2 sorption isotherms, and pyridine FTIR. Ba can be highly dispersed on Al2O3 covering the strong acid sites of Al2O3. In the catalytic dehydrochlorination of 1,2-dichloroethane (1,2-DCE), the Ba/Al2O3 catalysts present a high activity, of which Al2O3 is most active with 95% conversion at 325 °C, related to the more Lewis acidic Al3+ sites in a tetrahedral environment. 1,2-DCE adsorbs dissociatively on Lewis acid-base pair sites, forming chlorinated ethoxy species, which are supposed to be intermediate species for vinyl chloride (VC) production. At a temperature higher than 400 °C, the dehydrochlorination of VC occurs on the strong acid sites of Al2O3. Ba can promote greatly the selectivity for VC through a decrease in the strong acid sites. A high stable activity for dehydrochlorination and high selectivity for VC can be obtained over Ba/Al2O3 in the presence of oxygen.
- Bai, Shuxing,Dai, Qiguang,Chu, Xinxin,Wang, Xingyi
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- Surface kinetics using line of sight techniques: The reaction of chloroform with Cu(111)
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The adsorption of chloroform (CHCl3) on Cu(111) in the temperature range 100-480 K has been studied using line of sight sticking probability (LOSSP) measurements, line of sight temperature programmed desorption (LOSTPD), low energy electron diffraction (LEED), He I ultra-violet photoelectron spectroscopy (UPS) and work function measurements. Chloroform adsorbs molecularly at 100 K with a sticking probability of 0.98 ± 0.02, the monolayer reacting on heating to 170 K to form chemisorbed chlorine and adsorbed ethyne. The adsorbed ethyne desorbs at just above room temperature with first order kinetics, an activation energy of 77 ± 6 kJ mol-1 and a pre-exponential factor of 10(11±1) s-1. The sticking probability of chloroform on clean Cu(111) at 320 K is 0.23 ± 0.04, which corresponds to activated adsorption at zero coverage with an activation energy of 3.5 ± 0.7 kJ mol-1. The initial sticking probability is found to increase slightly for temperatures above room temperature, and also for temperatures below room temperature, while the sticking probability at finite coverage is greatly increased by the presence of the dissociation product, ethyne, on the surface. These observations are explained in terms of activated adsorption at zero coverage which becomes non-activated at finite coverage due to attractive intermolecular interactions between adsorbed chloroform molecules, and adsorbed chloroform and ethyne molecules.
- Jones, Robert G.,Clifford, Charles A.
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- Competition between photochemistry and energy transfer in ultraviolet-excited diazabenzenes. I. Photofragmentation studies of pyrazine at 248 nm and 266 nm
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The quantum yield for the formation of HCN from the photodissociation of pyrazine excited at 248 nm and 266 nm is determined by IR diode probing of the HCN photoproduct. HCN photoproducts from excited pyrazine are produced via three different dissociation channels, one that is extremely prompt and two others that are late. The total quantum yield from all reaction channels obtained at low quencher gas pressures, φ = 1.3 ± 0.2 for 248 nm and 0.5 ± 0.3 for 266 nm, is in agreement with preliminary studies of this process as well as recent molecular beam studies. To investigate if HCN production is the result of pyrazine multiphoton absorption, this photodissociation process has been further studied by observing the HCN quantum yield as a function of total quencher gas pressure (10 mTorr pyrazine, balance SF6) and as a function of 248 nm laser fluence from 2.8 to 82 mJ/cm2. At the highest SF6 pressures, the HCN quantum yield shows strong positive correlation with laser fluence, indicating that the prompt channel is the result of multiphoton absorption; however, at low pressure, the HCN quantum yield is affected little by changing laser fluence, indicating that the majority of the HCN photoproducts at low pressure are produced from pyrazine which has absorbed only one UV photon. At the lowest pressures sampled, HCN produced from the one-photon late process accounts for more than 95% of all HCN formed (at low laser fluence). At high pressures the single photon late pyrazine dissociation is quenched, and HCN produced at high quencher gas pressures comes only from the multiphoton absorption channel, which can be clearly observed to depend on laser fluence. The HCN quantum yield as a function of laser intensity at high pressure has been fit to a quadratic function that can be used to determine the amount of prompt unquenched HCN produced from multiphoton photodissociation. Additionally, the information theoretic prior functions for energy disposal in the 248 nm photodissociation of pyrazine to form HCN have also been developed. Prior functions for one, two, and three-photon absorption indicate that only HCN with near room temperature translational energy comes from the one-photon process and that all HCN molecules with large amounts of translational energy are produced by multiphoton processes. Finally, analysis of the quenching data within the context of a strong collision model allows an estimate of the rate constant for HCN production from pyrazine for the major late channel, kdls = 1.69 × 105 s-1, for 248 nm excitation, and kdls = 1.33 × 104 s-1 for 266 nm excitation. After 266 nm excitation, pyrazine produced by the major one-photon channel lives for almost an order of magnitude longer than after 248 nm excitation.
- Sevy, Eric T.,Muyskens, Mark A.,Rubin, Seth M.,Flynn, George W.,Muckerman, James T.
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- Photochemical reactions of cis- and trans-1,2-dichloroethene adsorbed on Pd(111) and Pt(111)
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The photochemical behaviors of cis- and trans-1,2-dichloroethene (DCE) adsorbed on Pd ( 111 ) and Pt ( 111 ) surfaces have been studied using electron energy loss spectroscopy ( EELS ) .For multilayer coverage on either metal surface, irradiation of physisorbed DCE at 110 K with broad band irradiation (λ > 200 nm) results in photoisomerization, cistrans.For monolayer coverage on Pt ( 111 ) at 110 K, photolysis of chemisorbed DCE causes loss of the two chlorine atoms to form a single hydrocarbon product, chemisorbed acetylene.Apparently, for λ > 237 nm, the chlorine atoms remain bound to the platinum surface whereas for shorter wavelengths, λ > 200 nm, the chlorine atoms leave the surface.These results are interpretable in terms of singlet excitation of the chemisorbed alkane followed by chlorine elimination on an excited singlet reaction surface.This study indicates that photochemistry of molecules chemisorbed on a metal surface is possible despite the proximity of the conducting surface.It shows that energy relaxation processes connected with this proximity are not prohibitively fast.
- Grassian, Vicki H.,Pimentel, George C.
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- Formation of Acetylene in the Reaction of Methane with Iron Carbide Cluster Anions FeC3? under High-Temperature Conditions
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The underlying mechanism for non-oxidative methane aromatization remains controversial owing to the lack of experimental evidence for the formation of the first C?C bond. For the first time, the elementary reaction of methane with atomic clusters (FeC3?) under high-temperature conditions to produce C?C coupling products has been characterized by mass spectrometry. With the elevation of temperature from 300 K to 610 K, the production of acetylene, the important intermediate proposed in a monofunctional mechanism of methane aromatization, was significantly enhanced, which can be well-rationalized by quantum chemistry calculations. This study narrows the gap between gas-phase and condensed-phase studies on methane conversion and suggests that the monofunctional mechanism probably operates in non-oxidative methane aromatization.
- Li, Hai-Fang,Jiang, Li-Xue,Zhao, Yan-Xia,Liu, Qing-Yu,Zhang, Ting,He, Sheng-Gui
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- Translational energy distributions and angular difference Doppler profiles of the excited hydrogen atom produced in e-C2H4 collisions: Dissociation dynamics of ethylene
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Formation of an excited hydrogen atom (H*) through electron-impact dissociation of ethylene has been investigate by measuring Doppler profiles of the Balmer-β line and their angular dependence at an optical resolution of 0.007 nm.The Doppler profiles show a clear anisotropy.The translational energy distribution (TED) and the angular difference Doppler profile were obtained.There are four major dissociation processes for the formation of H* (n = 4).Component 1 has a peak of TED at 1 eV, is produced in a perpendicular distribution, and should be produced by predissociation through the Rydberg states converging to the (1b1u)-1 state.Component 2 has a peak of TED at 1.8 eV, is produced in a parallel distribution, and should be produced through the Rydberg states converging to the (2ag)-1 state.Component 3 has a peak of TED at 2-6 eV and is produced in a parallel distribution.Component 4 has a peak of TED at 5-10 eV.Molecular orientation at the time of excitation was estimated; the molecular plane is perpendicular to the electron beam for component 1, and the C=C bond is perpendicular and the molecular plane is parallel to the electron beam for components 2 and 3.The asymmetry parameters of components 2 and 3 were 0.2: these values were much smaller than anticipated due largely to molecular rotation and deformation at the time of dissociation.
- Yonekura, Nobuaki,Nakashima, Keiji,Ogawa, Teiichiro
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- Photodissociation of 1,2-C2H2Br2 at 248 nm: Competition between three-body formation Br+Br+C2H2 and molecular Br2 elimination
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The photodissociation of 1,2-C2H2Br2 was studied using product translational spectroscopy. A detector consisting of an electron impact ionizer, quadrupole mass filter and Daly type ion counter was used to measure the dissociation production after travelling a flight path of 365 mm from the reaction zone. Experimental analysis suggested that the dissociation of the molecule into triple products was due to an asynchronous concerted reaction. Behavior of the molecule in the presence of additional bromine atom and the molecular elimination of Br2 were also studied. The product anisotropy indicated that both Br fragments were produced in a fraction of rotational period.
- Lee,Chou,Lee,Wang,Lin
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- Unimolecular Dissociation of Vinylacetylene: A Molecular Reaction
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The thermal decomposition of vinylacetylene (C4H4) has been studied in the shock tube with two time-resolved diagnostics, laser-schlieren (2percent and 4percent C4H4-Kr, 1650-2500 K, 110-427 Torr) and time-of-flight mass spectrometry (2percent C4H4-Ne, 1500-2000 K, 150-300 Torr).The time-of-flight mass spectra show dominant products C2H2 and C4H2 with a very consistent 5:1 ratio of C2H2 to C4H2, in essential agreement with earlier shock tube results.The laser-schlieren semilog density gradient profiles are all concave-upward, showing no trace of chain acceleration.Analysis of these profiles also sets the effective heat of reaction between 30 and 50 kcal/mol.Rate constants calculated from the zero-time gradients assuming ΔH0298 = 40 kcal/mol are fit with a routine RRKM model which indicates a barrier E0=79.5 +/- 3 kcal/mol.These observations and the time-of-flight product profiles are consistent with the molecular reactions C4H4 --> 2C2H2 (ΔH0298 = 39 kcal/mol)and C4H4 --> C4H2+H2(ΔH0298 = 42 kcal/mol).Detailed balance rate constants for 2C2H2 --> C4H4 are in good agreement with the extensive previous data on the second-order acetylene reaction, confirming that vinylacetylene is a direct and dominant product of C2H2 dimerization for moderate temperatures.Above 1500 K, the C4H4 dissociation shows significant falloff even for high pressures, and the now dominant C4H2 in C2H2 pyrolysis may then be formed in part through 2C2H2 --> C4H2 + H2.It is proposed that vinylacetylene dissociates as a substituted ethylene, either by 1,1-elimination of molecular hydrogen, leaving vinylidene acetylene which rapidly isomerizes to C4H2, or by 2,2-elimination of C2H2, followed by rapid isomerization of the vinylidene to a second C2H2.This mechanism is consistent with the observed barrier, provides a rationale for the constancy of the C2H2/C4H2 ratio, and offers a resonable explanation for the magnitude (A factor) of the observed rate constants.
- Kiefer, J. H.,Mitchell, K. I.,Kern, R. D.,Yong, J. N.
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- The synthesis of ternary acetylides with tellurium: Li2TeC2 and Na2TeC2
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The synthesis of ternary acetylides Li2TeC2 and Na2TeC2 is presented as the first example of ternary acetylides with metalloid elements instead of transition metals. The synthesis was carried out by the direct reaction of the corresponding bialkali acetylides with tellurium powder in liquid ammonia. Alternatively, the synthesis of Na2TeC2 was also carried out by the direct reaction of tellurium powder and two equivalents of NaC2H in liquid ammonia leading to Na2TeC2 and acetylene gas through an equilibrium containing the assumed NaTeC2H molecules besides the reactants and the products. The resulting disordered crystalline materials were characterized by X-ray diffraction and Raman spectroscopy. Implications of these new syntheses on the synthesis of other ternary acetylides with metalloid elements and transition metals are also discussed.
- Németh, Károly,Unni, Aditya K.,Kalnmals, Christopher,Segre, Carlo U.,Kaduk, James,Bloom, Ira D.,Maroni, Victor A.
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- Evidence for a difference in the dissociation mechanisms of acetylene (HCCH) and vinylidene (H2C=C:) from charge inversion mass spectrometry
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Vinylidene and acetylene are the simplest hydrocarbon isomers, and vinylidene is the simplest unsaturated carbene. The charge inversion mass spectra of C2H2+ cations derived from acetylene using Na, K, Rb and Cs targets were found to be clearly different from those derived from vinylidenechloride (1,1-dichloroethylene). The process of formation of the negative ions in charge inversion mass spectrometry is via near-resonant neutralization followed by spontaneous dissociation, and then endothermic negative ion formation. The intensity of the C2- peak relative to the C2H- peak in these spectra increased with decreasing ionization potential of the targets for both of the isomeric C2H2+ cations. The formation of the C2- anion is proposed to result from the dissociation of excited C2H2 neutrals into C2 and H2. The dependence on target species of the intensities of the C2- peak relative to the C2H- peak for HCCH and H2C=C: cannot be rationalized by the internal energy of the excited C2H2 neutrals. The differences indicate that the isomeric C2H2 neutrals dissociate into C2H and H prior to 1,2-hydrogen atom migration.
- Hayakawa, Shigeo,Tomozawa, Kouji,Takeuchi, Takae,Arakawa, Kazuo,Morishita, Norio
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- Two-photon photodissociation of gaseous azulene at 325 nm
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The two-photon photodissociation of gaseous azulene at 325 nm is reported.Acetylene is the major photodissociation product.The quantum yields for acetylene produced by irradiation of neat azulene at its normal vapor pressure and as a function of argon bath gas pressure are reported.The quantum yield of acetylene produced from irradiated azulene at its normal vapor pressure (ca. 10 m Torr) is ca. (5.85+/-1.46) * 10-6.Using a mechanism by which internal conversion precedes the absorption of the second photon, the two-photon absorption cross section is calculated.
- Hassoon, S.,Snavely, D. L.,Oref, I.
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- Influence of low-voltage discharge energy on the morphology of carbon nanostructures in induced benzene transformation
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The directions of the transformation of benzene induced by low-voltage discharges at various energies of pulsed discharges were revealed. This paper shows the dependencies of the morphology and other characteristics of nanostructures obtained in the induced transformation of benzene on the energy of pulsed discharges. Nanostructures with different morphologies are formed when the energy of the low-voltage discharges changes during the induced transformation of benzene in the liquid phase. Two types of carbon nanostructures were formed in the induced destruction of benzene with a 90 μF capacitor. The first type of structure includes graphite fibers, two- and three-layer graphene sheets, as well as two- and three-layer hollow spheres and microstructures in the form of CNHs. The microstructures of the second type were onion-like spheroids. An increase in the capacitance up to 20?090 μF led to the formation of two types of nanostructures: onion-like spheroids and carbon fibers. A further increase in the capacitance to 40?090 μF caused the formation of onion-like spheroids.
- Bodrikov, Ivan Vasilievich,Ivanova, Anna Gennadevna,Serov, Anton Igorevich,Titov, Dmitry Yurievich,Titov, Evgeny Yurievich,Vasiliev, Alexander Leonidovich
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p. 39428 - 39437
(2021/12/24)
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- Direct Evidence on the Mechanism of Methane Conversion under Non-oxidative Conditions over Iron-modified Silica: The Role of Propargyl Radicals Unveiled
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Radical-mediated gas-phase reactions play an important role in the conversion of methane under non-oxidative conditions into olefins and aromatics over iron-modified silica catalysts. Herein, we use operando photoelectron photoion coincidence spectroscopy to disentangle the elusive C2+ radical intermediates participating in the complex gas-phase reaction network. Our experiments pinpoint different C2-C5 radical species that allow for a stepwise growth of the hydrocarbon chains. Propargyl radicals (H2C?C≡C?H) are identified as essential precursors for the formation of aromatics, which then contribute to the formation of heavier hydrocarbon products via hydrogen abstraction–acetylene addition routes (HACA mechanism). These results provide comprehensive mechanistic insights that are relevant for the development of methane valorization processes.
- ?ot, Petr,Hemberger, Patrick,Pan, Zeyou,Paunovi?, Vladimir,Puente-Urbina, Allen,van Bokhoven, Jeroen Anton
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supporting information
p. 24002 - 24007
(2021/10/01)
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- Ethynylhydroxycarbene (H-CC-C¨-OH)
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The species on the C3H2O potential energy surface have long been known to play a vital role in extraterrestrial chemistry. Here we report on the hitherto uncharacterized isomer ethynylhydroxycarbene (H-CC-C¨-OH, 1) generated by high-vacuum flash pyrolysis of ethynylglyoxylic acid ethyl ester and trapped in solid argon matrices at 3 and 20 K. Upon irradiation at 436 nm trans-1 rearranges to its higher lying cis-conformer. Prolonged irradiation leads to the formation of propynal. When the matrix is kept in the dark, 1 reacts within a half-life of ca. 70 h to propynal in a conformer-specific [1,2]H-tunneling process. Our results are fully consistent with computations at the CCSD(T)/cc-pVTZ and the B3LYP/def2-QZVPP levels of theory.
- Bernhardt, Bastian,Ruth, Marcel,Eckhardt, André K.,Schreiner, Peter R.
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supporting information
p. 3741 - 3746
(2021/04/06)
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- Biochemical Characterization, Phytotoxic Effect and Antimicrobial Activity against Some Phytopathogens of New Gemifloxacin Schiff Base Metal Complexes
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String of Fe(III), Cu(II), Zn(II) and Zr(IV) complexes were synthesized with tetradentateamino Schiff base ligand derived by condensation of ethylene diamine with gemifloxacin. The novel Schiff base (4E,4′E)-4,4′-(ethane-1,2-diyldiazanylylidene)bis{7-[(4Z
- Mohamed, Amira A.,Elshafie, Hazem S.,Sadeek, Sadeek A.,Camele, Ippolito
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- Reactors for Preparing Valuable Hydrocarbons and Hydrogen From Methane Through Non-Oxidative Pyrolysis
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According to this disclosure, there is provided a pyrolysis reaction system and a direct non-oxidative methane coupling process using the same by which it is possible to reach the selectivity for good C≤10 hydrocarbons and at the same time to inhibit coke from being generated while a good methane conversion is maintained during direct conversion of methane into C2+ hydrocarbons through non-oxidative pyrolysis.
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Paragraph 0084-0091; 0099
(2021/10/11)
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- Practical Gas Cylinder-Free Preparations of Important Transition Metal-Based Precatalysts Requiring Gaseous Reagents
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A simple and safe setup for the synthesis of a selection of important transition metal-based precatalysts is reported, all requiring low-molecular weight gaseous reagents for their preparation. Hydrogen, carbon monoxide, ethylene, and acetylene are each liberated in a controlled manner from a corresponding easy-to-handle precursor in a closed two-chamber reactor. Gas cylinders and elaborate setups/techniques connected to handling toxic and/or flammable gases as reported in the literature can thus be avoided. The corresponding precatalysts are of high relevance in the active research fields of C-H bond activation, dehydrogenation, hydrogenation, and coupling reactions. The selection of complexes shown is meant to serve as examples for the usefulness and broadness of the presented methods, allowing precatalysts requiring gaseous reagents to become available for the research community.
- Ahrens, Alexander,Donslund, Bjarke S.,Gausas, Laurynas,Kristensen, Steffan K.,Skrydstrup, Troels,Sun, Hongwei
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supporting information
p. 2300 - 2307
(2021/09/28)
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- Reactor for Oxygen-free Direct Conversion of Methane and Method for Preparing Aromatic Hydrocarbon and Ethylene Using the Same
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The present invention relates to a reactor for nonoxidative, direct conversion of methane and a method for producing ethylene and aromatic compounds using the same. More particularly, the present invention relates to: a reactor for nonoxidative, direct conversion of methane, which, in the production of ethylene and aromatic compounds from methane, can maximize a catalytic reaction rate while minimizing coke formation at the same time, and can provide a high conversion rate of methane and a high yield of ethylene and aromatic compounds; and a method for producing ethylene and aromatic compounds using the reactor. The reactor for nonoxidative, direct conversion of methane includes an inlet part, a reaction part and an outlet part.COPYRIGHT KIPO 2021
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Paragraph 0086-0088; 0099-0105; 0107-0113
(2020/10/19)
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- SYSTEMS AND METHODS FOR PROCESSING GASES
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The invention includes a gas processing system for transforming a hydrocarbon- containing inflow gas into outflow gas products, where the system includes a gas delivery subsystem, a plasma reaction chamber, and a microwave subsystem, with the gas delivery subsystem in fluid communication with the plasma reaction chamber, so that the gas delivery subsystem directs the hydrocarbon-containing inflow gas into the plasma reaction chamber, and the microwave subsystem directs microwave energy into the plasma reaction chamber to energize the hydrocarbon-containing inflow gas, thereby forming a plasma in the plasma reaction chamber, which plasma effects the transformation of a hydrocarbon in the hydrocarbon-containing inflow gas into the outflow gas products, which comprise acetylene and hydrogen. The invention also includes methods for the use of the gas processing system.
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Paragraph 00107-00111; 00118-00121
(2020/03/15)
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- Synthesis, structure, and reactivity of a thermally stable dialkylgermylene
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The dialkylgermylene Trp*2Ge: (Trp*: peripherally extended sterically demanding alkyl groups based on the triptycyl (Trp) framework), was obtained from the reaction of Trp*Li with GeCl2¢ dioxane. The structure of Trp*2Ge: was unequivocally determined by NMR and UV-vis spectroscopy, mass spectrometry, and a single-crystal X-ray diffraction analysis. Moreover, the reactivity of Trp*2Ge: was examined.
- Minoura, Mao,Nishino, Ryohei,Sugamata, Koh,Suzuki, Fumiaki,Yukimoto, Mariko
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p. 249 - 251
(2020/04/27)
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- Features of the Thermolysis of Li, Na, and Cd Maleates
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Abstract: Processes of the multi-stage decomposition of maleic acid and Li, Na, and Cd maleates in an inert atmosphere are studied via thermal analysis with synchronous analysis of the composition of the released gases. Reaction mechanisms are proposed according to the data on the mass loss stages determined via thermal analysis, gaseous products, and the final solid decomposition products. It is shown that when heated to 700°C, Li and Na carbonates incorporated into the porous carbon matrix are the final products. Above 350°C, cadmium is reduced from oxide to metal and evaporates to form a porous carbon residue as the only product of thermolysis. All carbon products are X-ray amorphous. Maleic acid decomposes completely into gaseous products in the range of 133–239°C. The maleate ion is more stable in the structure of lithium maleate than in free maleic acid, and Na and Cd cations reduce its stability.
- Avdin, V. V.,Merzlov, S. V.,Nayfert, S. A.,Polozov, M. A.,Polozova, V. V.,Sakthi Dharan, C. P.,Taskaev, S. V.,Zherebtsov, D. A.
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p. 1311 - 1318
(2020/07/21)
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- Isotope Effects in Plasmonic Photosynthesis
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The photoexcitation of plasmonic nanoparticles has been shown to drive multistep, multicarrier transformations, such as the conversion of CO2 into hydrocarbons. But for such plasmon-driven chemistry to be precisely understood and modeled, the critical photoinitiation step in the reaction cascade must be identified. We meet this goal by measuring H/D and 12C/13C kinetic isotope effects (KIEs) in plasmonic photosynthesis. In particular, we found that the substitution of H2O with D2O slows hydrocarbon production by a factor of 5–8. This primary H/D KIE leads to the inference that hole-driven scission of the O?H bond in H2O is a critical, limiting step in plasmonic photosynthesis. This study advances mechanistic understanding of light-driven chemical reactions on plasmonic nanoparticles.
- Jain, Prashant K.,Yu, Sungju
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supporting information
p. 22480 - 22483
(2020/10/12)
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- Main Gaseous Products of Microwave Discharge in Various Liquid Hydrocarbons
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Abstract: Main gaseous products (H2, C2H2, C2H4, CH4) formed by microwave discharge in a number of liquid alkanes, cycloalkanes, and aromatic hydrocarbons have been studied using gas chromatography. It has been shown that the products of the discharge in these cycloalkanes and aromatic compounds bearing no side groups almost do not contain methane or ethylene, unlike the case of alkanes.
- Averin,Lebedev, Yu. A.,Tatarinov
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p. 331 - 335
(2019/08/15)
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- Compact solid oxide fuel cells and catalytic reformers based on microtubular membranes
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AC heated oxygen-permeable microtubular membranes with the composition Ba0.5Sr0.5Co0.78W0.02Fe0.2O3-δ were used to provide catalytic reforming of methane into C2- hydrocarbons. The methane conversion degree about 60% and acetylene yield about 27% at 1200 °C was achieved. Microtubular solid oxide fuel cells based on gadolinium-doped ceria with perovskite-like cathode material composed of Ba0.5Sr0.5Co0.75Mo0.05Fe0.2O3-δ were prepared. The MT-SOFC demonstrates maximum power densities of 50, 100, 200 mW/cm2 at 550, 600, 650 °C, respectively with humidified H2 as fuel and ambient air as oxidant.
- Popov, Mikhail P.,Maslennikov, Daniel V.,Gainutdinov, Igor I.,Gulyaev, Igor P.,Zagoruiko, Andrey N.,Nemudry, Alexander P.
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p. 167 - 170
(2018/11/30)
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- Conversion of methane to C2 and C3 hydrocarbons over TiO2/ZSM-5 core-shell particles in an electric field
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Catalytic conversion of methane (CH4) to light olefins is motivated by increasing recoverable reserves of methane resources, abundantly available in natural gas, shale gas, and gas hydrates. The development of effective processes for conversion of CH4 to light olefins is still a great challenge. The interface of ZSM-5 zeolite and TiO2 nanoparticles is successfully constructed in their core-shell particles via mechanochemical treatment with high shear stress. The oxidative coupling of methane at a low temperature under application of an electric field may be induced by the O2 activation via electrons running through the surface of TiO2 located at the interface of TiO2 and zeolite particles. Moreover, C3H6 was also produced by the ethylene to propylene (ETP) reaction catalyzed by Br?nsted acid sites in the ZSM-5 zeolite within core-shell particles.
- Han, Qiao,Tanaka, Atsuhiro,Matsumoto, Masayuki,Endo, Akira,Kubota, Yoshihiro,Inagaki, Satoshi
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p. 34793 - 34803
(2019/11/14)
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- Identification of cb1 receptor allosteric sites using force-biased mmc simulated annealing and validation by structure-activity relationship studies
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Positive allosteric modulation of the cannabinoid 1 receptor (CB1R) has demonstrated distinct therapeutic advantages that address several limitations associated with orthosteric agonism and has opened a promising therapeutic avenue for further drug development. To advance the development of CB1R positive allosteric modulators, it is important to understand the molecular architecture of CB1R allosteric site(s). The goal of this work was to use Force-Biased MMC Simulated Annealing to identify binding sites for GAT228 (R), a partial allosteric agonist, and GAT229 (S), a positive allosteric modulator (PAM) at the CB1R. Our studies suggest that GAT228 binds in an intracellular (IC) TMH1-2-4 exosite that would allow this compound to act as a CB1 allosteric agonist as well as a CB1 PAM. In contrast, GAT229 binds at the extracellular (EC) ends of TMH2/3, just beneath the EC1 loop. At this site, this compound can act as CB1 PAM only. Finally, these results were successfully validated through the synthesis and biochemical evaluation of a focused library of compounds.
- Hurst, Dow P.,Garai, Sumanta,Kulkarni, Pushkar M.,Schaffer, Peter C.,Reggio, Patricia H.,Thakur, Ganesh A.
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supporting information
p. 1216 - 1221
(2019/08/27)
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- Efficient conversion of ethanol to 1-butanol and C5-C9 alcohols over calcium carbide
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Production of 1-butanol or alcohols with 4-9 carbon atoms (C4-C9 alcohols) from widely available bio-ethanol has attracted much interest in recent years in academia and industry of renewable chemicals and liquid fuels. This work discloses for the first time that calcium carbide (CaC2) has a superior catalytic activity in condensation of ethanol to C4-C9 alcohols at 275-300 °C. The 1-butanol yield reached up to 24.5% with ethanol conversion of 62.4% at the optimized conditions. The by-products are mainly alcohols with 5-9 carbons besides 2-butanol, and the total yield of all the alcohols reached up to 56.3%. The reaction route was investigated through controlled experiments and quantitative analysis of the products. Results indicated that two reaction routes, aldol-condensation and self-condensation, took place simultaneously. The aldol-condensation route involves coupling of ethanol with acetaldehyde (formed from ethanol dehydrogenation) to form 2-butenol, which is subsequently hydrogenated to 1-butanol. The alkynyl moiety in CaC2 plays an important role in the catalytic pathways of both routes and affords the good activity of CaC2. CaC2 is converted to acetylene [C2H2] and calcium hydroxide [Ca(OH)2] simultaneously by the H2O that was generated from the condensation of alcohols.
- Wang, Dong,Liu, Zhenyu,Liu, Qingya
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p. 18941 - 18948
(2019/07/04)
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- Ambient-temperature oxidative coupling of methane in an electric field by a cerium phosphate nanorod catalyst
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CePO4 nanorods with uniform surface Ce sites could work as a durable catalyst and showed the highest C2 yield of 18% in an electric field without the need for external heating, which was comparable to that reported for high-performance catalysts at high temperature (>900 K).
- Sato, Ayaka,Ogo, Shuhei,Kamata, Keigo,Takeno, Yuna,Yabe, Tomohiro,Yamamoto, Tomokazu,Matsumura, Syo,Hara, Michikazu,Sekine, Yasushi
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supporting information
p. 4019 - 4022
(2019/04/10)
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- Hydrocarbon Synthesis via Photoenzymatic Decarboxylation of Carboxylic Acids
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A recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) bears the promise for the efficient and selective synthesis of hydrocarbons from carboxylic acids. CvFAP, however, exhibits a clear preference for long-chain fatty acids thereby limiting its broad applicability. In this contribution, we demonstrate that the decoy molecule approach enables conversion of a broad range of carboxylic acids by filling up the vacant substrate access channel of the photodecarboxylase. These results not only demonstrate a practical application of a unique, photoactivated enzyme but also pave the way to selective production of short-chain alkanes from waste carboxylic acids under mild reaction conditions.
- Zhang, Wuyuan,Ma, Ming,Huijbers, Mieke M. E.,Filonenko, Georgy A.,Pidko, Evgeny A.,Van Schie, Morten,De Boer, Sabrina,Burek, Bastien O.,Bloh, Jonathan Z.,Van Berkel, Willem J. H.,Smith, Wilson A.,Hollmann, Frank
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supporting information
p. 3116 - 3120
(2019/03/06)
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- Boosting CO2 photoreduction activity by large Fresnel lens concentrated solar light
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CO2 photoreduction to hydrocarbons is an important process for solar energy. Herein, the reaction rate is massively pushed up by large Fresnel lens (diameter = 1 m) concentrating solar light technology. The maximum CH4 yield rate reached 3157.2 μmol·g?1·h?1, C2H4 rate to 511.6 μmol·g?1·h?1, C2H6 to 1346.0 μmol·g?1·h?1, and the CO2 conversion reached 3.94%. The total solar to chemical energy conversion efficiency got 0.15%. The results are considered from the intensification of reaction conditions such as light intensity, reaction temperature, and pressure of H2O and CO2. The findings will be beneficial for the further discussion of CO2 photoreduction basing upon the existed catalysts system, and decrease the research threshold in CO2 photoreduction.
- Fang, Xiaoxiang,Gao, Zhihong,Lu, Hanfeng,Zhang, Zekai
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- Direct Non-Oxidative Methane Conversion in a Millisecond Catalytic Wall Reactor
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Direct non-oxidative methane conversion (DNMC) has been recognized as a single-step technology that directly converts methane into olefins and higher hydrocarbons. High reaction temperature and low catalyst durability, resulting from the endothermic reaction and coke deposition, are two main challenges. We show that a millisecond catalytic wall reactor enables stable methane conversion, C2+ selectivity, coke yield, and long-term durability. These effects originate from initiation of the DNMC on a reactor wall and maintenance of the reaction by gas-phase chemistry within the reactor compartment. The results obtained under various temperatures and gas flow rates form a basis for optimizing the process towards lighter C2 or heavier aromatic products. A process simulation was done by Aspen Plus to understand the practical implications of this reactor in DNMC. High carbon and thermal efficiencies and low cost of the reactor materials are realized, indicating the technoeconomic viability of this DNMC technology.
- Oh, Su Cheun,Schulman, Emily,Zhang, Junyan,Fan, Jiufeng,Pan, Ying,Meng, Jianqiang,Liu, Dongxia
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supporting information
p. 7083 - 7086
(2019/04/27)
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- Nonoxidative Direct Conversion of Methane on Silica-Based Iron Catalysts: Effect of Catalytic Surface
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For a stable methane to olefins, aromatics, and hydrogen (MTOAH) reaction, 0.27-0.43 wt % Fe-containing silica catalysts were synthesized through various preparation methods and tested. The presence of Fe species in SiO2 mixtures increased the true and apparent densities of the catalysts during the melt-fusing process at 1700 °C. Several characterizations (i.e., H2-TPR, TEM, and XAS) revealed that partially reduced iron oxide (Fe3O4) predominantly existed in cristobalite (CRS) in the melt-fused catalysts. The FeCRS catalyst prepared from fayalite and quartz by the melt-fusing method showed a higher resistance to structural sintering and coke deposition than other Fe catalysts during MTOAH at 1020 °C. It also showed a 40% higher apparent activation energy for coke formation than for methane consumption in the temperature range of 1000 to 1040 °C. Increased CRS surfaces increased the coke selectivity, indicating that even the pure CRS surface acts as a chain reaction terminator to form coke. At the same space velocity (9400 h-1), the FeCRS catalyst was more selective in producing C2 (ethane, ethylene, and acetylene), C3-C5 olefins, and aromatics than pure CRS and other Fe catalysts. At a steady state, the FeCRS surface was most suitable for methane conversion, being 2.3 times more efficient than without a catalytic surface. The FeCRS catalyst exhibited a stable activity and low coke selectivity, even for 50 h, in the MTOAH reaction. EXAFS profiles showed that highly dispersed Fe carbide with Fe-Si coordination was formed in the FeCRS catalyst, and electronic structure calculations indicated that these confined Fe sites were more favorable for methyl radical formation and a high coke resistance than Fe3C clusters. By optimizing reaction parameters, the FeCRS catalyst exhibited 6.9-5.8% methane conversion and 86.2% C2 selectivity for 100 h with cofeeding of 50% H2 at 1080 °C.
- Han, Seung Ju,Lee, Sung Woo,Kim, Hyun Woo,Kim, Seok Ki,Kim, Yong Tae
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p. 7984 - 7997
(2019/08/21)
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- METHOD FOR PREPARATION OF NANOCERIA SUPPORTED ATOMIC NOBLE METAL CATALYSTS AND THE APPLICATION OF PLATINUM SINGLE ATOM CATALYSTS FOR DIRECT METHANE CONVERSION
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Described are methods for converting methane to olefins, aromatics, or a combination thereof using a single atom catalyst comprising CeO2 nanoparticles impregnated with individual atoms of noble metals including Pt, Pd, Rh, Ru, Ag, Au, Ir, or a combination thereof. These single atom catalysts of the present invention are heated with methane to form olefins and aromatics.
- -
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Page/Page column 17
(2019/09/12)
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- METHOD OF PRODUCING VINYL CHLORIDE
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A method of producing vinyl chloride is provided in the present invention. The method includes the following steps. First, 1,2-dichloroethane (EDC) is introduced into a reactor, and a residence time of the EDC in an ionic liquid catalyst is 5 seconds to 100 seconds, so as to perform a catalytic cleavage reaction. The ionic liquid catalyst is in a liquid phase. The ionic liquid catalyst includes tributylalkyl phosphonium halide, and the alkyl includes an alkyl group having 3 to 16 carbon atoms.
- -
-
Paragraph 0031; 0038; 0039
(2020/01/27)
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- Catalytic oxidative conversion of methane and ethane over polyoxometalate-derived catalysts in electric field at low temperature
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We examined oxidative coupling of methane (OCM) and oxidative dehydrogenation of ethane (ODE) over various polyoxometalate supported CeO2 catalysts at 423 K in an electric field. Tetrabutylammonium (TBA) salt of Keggin-type phosphotungstate (PW12O40) supported CeO2 catalysts ((TBA)3PW12O40/CeO2) showed high activities for OCM and ODE in the electric field (3 mA) at 423 K, although the catalyst without the electric field showed extremely low activities at such low temperature. FT-IR spectra and XRD patterns confirmed that the structure of (TBA)3PW12O40/CeO2 was changed to Ce2(WO4)3/CeO2 after reactions with the electric field, and it acted as an active site structure for OCM and ODE with the electric field. Results of activity tests revealed that the C2H6 production was a main reaction in OCM with the electric field, and C2H4 was formed through a successive oxidative dehydrogenation of the formed C2H6. Periodic operation tests demonstrated that reactive oxygen species suitable for ODE were formed on the catalyst surface of Ce2(WO4)3 in the electric field.
- Ogo, Shuhei,Iwasaki, Kousei,Sugiura, Kei,Sato, Ayaka,Yabe, Tomohiro,Sekine, Yasushi
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- INTEGRATED PROCESS COMBINING METHANE OXIDATIVE COUPLING AND DRY METHANE REFORMING
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The disclosure concerns processes for conversion of methane to C2 hydrocarbons comprising: (i) contacting methane with oxygen in the presence of a first catalyst in a first reactor to produce a first reaction product comprising C2 hydrocarbons and CO2; (ii) separating the first reaction product to produce a first stream comprising C2 hydrocarbons and a second stream comprising methane, CO and CO2; and (iii) contacting the second stream with oxygen and additional CO2 in the presence of a second catalyst in a second reactor to produce a second reaction product comprising H2 and CO.
- -
-
Paragraph 00125
(2018/03/26)
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- Nanoceria-Supported Single-Atom Platinum Catalysts for Direct Methane Conversion
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Nanoceria-supported atomic Pt catalysts (denoted as Pt1@CeO2) have been synthesized and demonstrated with advanced catalytic performance for the nonoxidative, direct conversion of methane. These catalysts were synthesized by calcination of Pt-impregnated porous ceria nanoparticles at high temperature (ca. 1000 °C), with the atomic dispersion of Pt characterized by combining aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses. The Pt1@CeO2 catalysts exhibited much superior catalytic performance to its nanoparticulated counterpart, achieving 14.4% of methane conversion at 975 °C and 74.6% selectivity toward C2 products (ethane, ethylene, and acetylene). Comparative studies of the Pt1@CeO2 catalysts with different loadings as well as the nanoparticulated counterpart reveal the single-atom Pt to be the active sites for selective conversion of methane into C2 hydrocarbons.
- Xie, Pengfei,Pu, Tiancheng,Nie, Anmin,Hwang, Sooyeon,Purdy, Stephen C.,Yu, Wenjian,Su, Dong,Miller, Jeffrey T.,Wang, Chao
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p. 4044 - 4048
(2018/05/23)
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- The selective formation of a 1,2-disilabenzene from the reaction of a disilyne with phenylacetylene
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A stable 3,5-diphenyl-1,2-disilabenzene was selectively synthesized by the reaction between the isolable disilyne TbbSiSiTbb (Tbb = 2,6-[CH(SiMe3)2]2-4-t-Bu-phenyl) with phenylacetylenes. Its molecular structure and physical properties were examined and compared to those of the 1,2-disilabenzene that was obtained from the reaction between TbbSiSiTbb and acetylene. Moreover, a plausible formation mechanism for this reaction is discussed.
- Sugahara, Tomohiro,Guo, Jing-Dong,Hashizume, Daisuke,Sasamori, Takahiro,Nagase, Shigeru,Tokitoh, Norihiro
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supporting information
p. 13318 - 13322
(2018/10/15)
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- 2,5-Digermaselenophenes: Germanium Analogues of Selenophenes
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A stable crystalline 2,5-digermaselenophene was synthesized. In contrast to hitherto reported selenophenes, this digermaselenophene exhibits a trans-pyramidalized structure, which is due to its electronic properties. The practical utility of this 2,5-digermaselenophene is reflected in its ability to activate dihydrogen and acetylene at room temperature in the absence of a transition-metal complex, and this behavior can be rationalized on the basis of its physicochemical properties, which are characterized by considerable electron-donating and -accepting abilities.
- Sugahara, Tomohiro,Sasamori, Takahiro,Tokitoh, Norihiro
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supporting information
p. 11206 - 11209
(2018/09/12)
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- Formation of 1,1-dichloro-2-vinyl-1-silacyclopropane by a photoinduced reaction between dichlorosilylene and 1,3-butadiene
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A matrix FTIR study of interaction between SiCl2 and 1,3-butadiene revealed that at low temperatures, it stops at the step of complexation between the reactants. This allowed us to investigate a photochemical version of this interaction resulti
- Boganov, Sergey E.,Promyslov, Vladimir M.,Rynin, Stanislav S.,Krylova, Irina V.,Egorov, Mikhail P.
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p. 574 - 576
(2018/12/13)
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- METHOD FOR CHLORINATION AND DEHYDROGENATION OF ETHANE
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The present invention relates to a method for chlorination and dehydrogenation of ethane, comprising: mixing and reacting a low-melting-point metal chloride with C2H6, such that the low-melting-point metal chloride is reduced to a liquid-state low-melting-point metal, and the C2H6 is chlorinated and dehydrogenized to give a mixed gas containing HCl, C2H6, C2H4, C2H2 and C2H3Cl. In the method, the low-melting-point metal chloride is used as a raw material for chlorination and dehydrogenation, and the low-melting-point metal produced after the reaction is used as an intermediate medium. The method has the characteristics of simple process, low cost and high yield. Moreover, some acetylene and vinyl chloride can be produced as by-products at the same time when the ethylene is produced, by controlling the ratio of ethane to the chloride as desired in production.
- -
-
Paragraph 0031; 0034; 0037-0039; 0040; 0043
(2018/04/03)
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- Cobalt-Iron-Manganese Catalysts for the Conversion of End-of-Life-Tire-Derived Syngas into Light Terminal Olefins
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Co-Fe-Mn/γ-Al2O3 Fischer–Tropsch synthesis (FTS) catalysts were synthesized, characterized and tested for CO hydrogenation, mimicking end-of-life-tire (ELT)-derived syngas. It was found that an increase of C2-C4 olefin selectivities to 49 % could be reached for 5 wt % Co, 5 wt % Fe, 2.5 wt % Mn/γ-Al2O3 with Na at ambient pressure. Furthermore, by using a 5 wt % Co, 5 wt % Fe, 2.5 wt % Mn, 1.2 wt % Na, 0.03 wt % S/γ-Al2O3 catalyst the selectivity towards the fractions of C5+ and CH4 could be reduced, whereas the selectivity towards the fraction of C4 olefins could be improved to 12.6 % at 10 bar. Moreover, the Na/S ratio influences the ratio of terminal to internal olefins observed as products, that is, a high Na loading prevents the isomerization of primary olefins, which is unwanted if 1,3-butadiene is the target product. Thus, by fine-tuning the addition of promoter elements the volume of waste streams that need to be recycled, treated or upgraded during ELT syngas processing could be reduced. The most promising catalyst (5 wt % Co, 5 wt % Fe, 2.5 wt % Mn, 1.2 wt % Na, 0.03 wt % S/γ-Al2O3) has been investigated using operando transmission X-ray microscopy (TXM) and X-ray diffraction (XRD). It was found that a cobalt-iron alloy was formed, whereas manganese remained in its oxidic phase.
- Falkenhagen, Jan P.,Maisonneuve, Lise,Paalanen, Pasi P.,Coste, Nathalie,Malicki, Nicolas,Weckhuysen, Bert M.
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supporting information
p. 4597 - 4606
(2018/03/06)
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- One-pot synthesis of 1-monosubstituted-1, 2, 3-triazoles from 2-methyl-3-butyn-2-ol
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An efficient method for the synthesis of 1-monosubstituted-1, 2, 3-triazoles from 2-methyl-3-butyn-2-ol under copper catalyst conditions has been developed through a one-step one-pot sequence. This method provides a concise and efficient pathway to synthesize 1-monosubstituted-1, 2, 3-triazole derivatives in good to excellent yields.
- Liu, Yaowen,Han, Chunmei,Ma, Xinyuan,Yang, Jianhua,Feng, Xuepu,Jiang, Yubo
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supporting information
p. 650 - 653
(2018/01/15)
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- Potassium Dimesitylphosphinite Catalyzed Intermolecular Hydrophosphorylation of Alkynes
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In this investigation we evaluated the scope of the intermolecular hydrophosphorylation (Pudovik reaction) of alkynes R1-C-C-R2 (R1 = H, alkyl, Ph; R2 = alkyl, Ph, COOMe, SiMe3, Si(iPr)3) with bis(2,4,6-trimethylphenyl)phosphane oxide (dimesitylphosphane oxide, Mes2P(O)H) in tetrahydrofuran at room temperature or 65 °C, catalyzed with 5 or 10 mol % of potassium dimesitylphosphinite (Mes2P-O-K), yielding alkenyldimesitylphosphane oxides (Mes2P(O)-C(R1)=C(H)R2). This procedure requires substituents with a -I effect at the C-C triple bond, whereas alkyl-substituted alkynes are inactive under these reaction conditions. The hydrophosphorylation proceeds regioselectively, but E/Z isomer mixtures are obtained. E/Z isomerization occurs at elevated temperatures with an estimated energy barrier of 59 kJ mol-1 (R1 = Me; R2 = Ph). Trimethylsilyl substituents at the alkyne functionality (R1 = H, nBu; R2 = SiMe3) destabilize the product, leading to degradation and formation of Mes2P-O-SiMe3 and R1-C-C-H.
- H?rling, Stephan M.,Fener, Benjamin E.,Krieck, Sven,G?rls, Helmar,Westerhausen, Matthias
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p. 4380 - 4386
(2019/01/03)
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- Direct conversion of methane over oxide-type catalysts supported on mesoporous silica under electric discharge
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Direct conversion of methane over oxide-type catalysts supported on mesoporous material under the dielectric barrier discharge plasma was investigated in the present study. The oxide catalysts (MgO and NiO) supported on SBA-15 was prepared by a hydrothermal and wet-impregnation method. The low-angle XRD patterns and TEM indicate that the ordered mesoporous structure was well maintained during the catalyst preparation and reaction processes. We also conducted direct conversion of methane using the catalysts under the plasma. As a result, the specific surface area of bare SBA-15 was much higher than that of the NiO/SBA-15, followed by MgO/SBA-15. Overall, the CH4 conversion increased with increasing the specific surface area. And C2 selectivity decreased with increasing the specific surface area.
- Kim, Taegyu,Park, Daeil
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p. 2567 - 2570
(2017/03/09)
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- Is the tungsten(IV) complex (NEt4)2[WO(mnt)2] a functional analogue of acetylene hydratase?
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The tungsten(IV) complex (Et4N)2[W(O)(mnt)2] (1; mnt = maleonitriledithiolate) was proposed (Sarkar et al., J. Am. Chem. Soc. 1997, 119, 4315) to be a functional analogue of the active center of the enzyme acetylene hydratase from Pelobacter acetylenicus, which hydrates acetylene (ethyne; 2) to acetaldehyde (ethanal; 3). In the absence of a satisfactory mechanistic proposal for the hydration reaction, we considered the possibility of a metal-vinylidene type activation mode, as it is well established for rutheniumbased alkyne hydration catalysts with anti-Markovnikov regioselectivity. To validate the hypothesis, the regioselectivity of tungsten- catalyzed alkyne hydration of a terminal, higher alkyne had to be determined. However, complex 1 was not a competent catalyst for the hydration of 1-octyne under the conditions tested. Furthermore, we could not observe the earlier reported hydration activity of complex 1 towards acetylene. A critical assessment of, and a possible explanation for the earlier reported results are offered. The title question is answered with "no".
- Schreyer, Matthias,Hintermann, Lukas
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supporting information
p. 2332 - 2339
(2017/11/16)
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- Infrared multiphoton dissociation of tetramethoxygermane
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Infrared multiphoton dissociation of Ge(OCH3)4 molecules by irradiation with a pulsed TEA CO2 laser has been studied. The basic characteristics of the process have been experimentally investigated. The spectral characterization of the dissociation has been made. The product composition of the dissociation has been analyzed, and possible dissociation pathways have been proposed.
- Koshlyakov,Chesnokov,Kuibida
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- Hydrogen-Permeable Tubular Membrane Reactor: Promoting Conversion and Product Selectivity for Non-Oxidative Activation of Methane over an FeSiO2Catalyst
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Non-oxidative methane conversion over FeSiO2catalyst was studied for the first time in a hydrogen (H2) permeable tubular membrane reactor. The membrane reactor is composed of a mixed ionic–electronic SrCe0.7Zr0.2Eu0.1O3?δthin film (≈20 μm) supported on the outer surface of a one-end capped porous SrCe0.8Zr0.2O3?δtube. Significant improvement in CH4conversion was achieved upon H2removal from the membrane reactor compared to that in a fixed-bed reactor. The FeSiO2catalyst in the H2permeable membrane reactor demonstrated a stable ≈30 % C2+single-pass yield, with up to 30 % CH4conversion and 99 % selectivity to C2(ethylene and acetylene) and aromatic (benzene and naphthalene) products, at the tested conditions. The selectivity towards C2or aromatics was manipulated purposely by adding H2into or removing H2from the membrane reactor feed and permeate gas streams.
- Sakbodin, Mann,Wu, Yiqing,Oh, Su Cheun,Wachsman, Eric D.,Liu, Dongxia
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p. 16149 - 16152
(2016/12/26)
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- Reaction of a stable digermyne with acetylenes: Synthesis of a 1,2-digermabenzene and a 1,4-digermabarrelene#
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Reactions between acetylenes and a stable digermyne bearing 4-t-Bu-2,6-[CH(SiMe3)2]2-C6H2 (Tbb) groups afforded the corresponding stable 1,2-digermabenzenes together with the respective 1,4-digermabarrelenes. The properties of the obtained products and the reaction mechanism are discussed on the basis of experimental and theoretical results. Especially, the aromaticity of the newly obtained 1,2-digermabenzene has been discussed on the detailed calculations, revealing its aromatic character to some degree.
- Sugahara, Tomohiro,Guo, Jing-Dong,Sasamori, Takahiro,Karatsu, Yusaku,Furukawa, Yukio,Ferao, Arturo Espinosa,Nagase, Shigeru,Tokitoh, Norihiro
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p. 1375 - 1384
(2017/08/01)
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- Highly Efficient Conversion of Methane to Olefins via a Recycle-Plasma-Catalyst Reactor
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Abstract: Spark discharge plasma is an efficient means to activate methane. In this work methane was converted to olefins via a two stage recycle-plasma-catalyst reactor. A recycle spark discharge plasma reactor was employed in the first stage to actively convert methane to a mixture comprising mainly acetylene and hydrogen. The mass transfer in the pulsed spark discharge channel was strengthened by recycling part of plasma effluent to the entrance, which improved the reactivity and energy efficiency of the plasma reactor. Pd and Ni based MgAl2O4 supported catalysts were employed in the second stage to selectively hydrogenate acetylene in the plasma reactor effluent. With the conversion of methane of 73 % the integration of recycle plasma and catalyst reactor may obtain a ethylene yield of 55 and 35 % on 0.3?wt% Pd-0.6?wt% Ag/MgAl2O4 and 2.5?wt% Ni-7.5?wt%-Zn/MgAl2O4 catalysts, respectively. Other than ethylene about 23 % of methane was transformed to C3–C5 light olefins over cheap 2.5?wt% Ni-7.5?wt% Zn/MgAl2O4 catalysts. Graphical Abstract: [Figure not available: see fulltext.]
- Wang, Bo,Guan
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p. 2193 - 2199
(2016/10/18)
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- Biosynthesis of isoxazolin-5-one and 3-nitropropanoic acid containing glucosides in juvenile Chrysomelina
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Stable-isotope-labeled precursors were used to establish the biosynthetic pathway leading from β-alanine towards isoxazolin-5-one glucoside 1 and its 3-nitropropanoate (3-NPA) ester 2 in Chrysomelina larvae. Both structural elements originate from sequestered plant-derived β-alanine or from propanoyl-CoA that is derived from the degradation of some essential amino acids, e.g. valine. β-Alanine is converted into 3-NPA and isoxazolinone 5 by consecutive oxidations of the amino group of β-Ala. Substituting the diphospho group of α-UDP-glucose with 5 generates the isoxazolin-5-one glucoside 1, which serves in the circulating hemolymph of the larva as a platform for esterification with 3-nitropropanoyl-CoA. The pathway was validated with larvae of Phaedon cochleariae, Chrysomela populi as well as Gastrophysa viridula.
- Becker, Tobias,Ploss, Kerstin,Boland, Wilhelm
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supporting information
p. 6274 - 6280
(2016/07/11)
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- A method of continuous by ethane system ethylene
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The invention relates to a method for continuously preparing ethylene by using ethane. The method comprises the following steps: firstly, enabling ethane to react with NiCl2 to obtain C2H4 and HCl mixed gas; reducing solid NiCl2 into Ni; absorbing HCl from the C2H4 and HCl mixed gas by using a circulating NiCl2 solution; precipitating, crystalizing and separating the NiCl2 solution in which HCl is absorbed to obtain solid NiCl2 and a hydrochloric acid solution; drying the obtained solid NiCl2 and recycling; absorbing C2H4 gas from which HCl gas is removed, and performing rectification separation to obtain a C2H4 product; enabling the hydrochloric acid solution to react with Ni generated in the previous reaction to obtain H2 and a NiCl2 solution; recycling the obtained NiCl2 solution. During the process of the method, Ni is taken as an intermediate medium for circular reaction, and the method has the characteristics of low energy consumption, high yield, and use of recyclable medium nickel and capability of producing a byproduct H2 energy.
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Paragraph 0048-0056
(2017/03/14)
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- A new process for enhancing conversion of methyl vinyl ether to propylene yields with Al2O3 hollow spheres
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Al2O3 hollow spheres were successfully synthesized via a simple template method and used to catalyze a new process from methyl vinyl ether to propylene. In this study, it not only indicated that a two-step integration process from acetylene and methanol to propylene is feasible but the prepared catalyst could also adjust the distribution of the products. First, colloidal carbon spheres were formed by the hydrothermal synthesis method, and then the template was used to prepare hollow spheres of Al2O3. EDS, XRD, SEM, and TEM all showed that the catalyst was composed of only O and Al and the structures were hollow spheres. In the new process tests, the low carbon olefins are detected as the main products, alkanes are nearly not observed. The participation of Al2O3 hollow spheres could significantly enhance the selectivity of olefins especially for propylene compared to the results without catalysts. Furthermore, the effects of temperature on the products were also investigated, and a possible radical-involved reaction mechanism is discussed in detail at the end.
- Wang, Yang,Zhang, Wenyu,Zha, Daoan,Hu, Jiaji,Li, Wei,Duan, Wubiao,Liu, Bo
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p. 8736 - 8742
(2016/02/05)
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- Study of the Formation of the First Aromatic Rings in the Pyrolysis of Cyclopentene
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The thermal decomposition of cyclopentene was studied in a jet-stirred reactor operated at constant pressure and temperature to provide new experimental information about the formation of the first aromatic rings from cyclic C5 species. Experim
- Herbinet, Olivier,Rodriguez, Anne,Husson, Benoit,Battin-Leclerc, Frédérique,Wang, Zhandong,Cheng, Zhanjun,Qi, Fei
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p. 668 - 682
(2016/02/23)
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- Chemo-, regio-, and stereoselective hydroboration of conjugated enyne alcohol/amine: Facile synthesis of Z,Z-/Z,E-1,3-dien-1/2-ylboronic ester bearing hydroxyl/amino group
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Hydroboration of conjugated enyne alcohol/amine is studied by using copper salts and bis(pinacolato)diboron as pre-catalysts and boron source respectively. It is suggested that the chemo-selectivity is derived from a combined electronic influence of the heteroatoms on the substrate and the ligand on the transition metal. The regioselectivity is probably dominated mainly by electronic effect of the alkyne substituent. This study resulted in a highly selective protocol to access Z,Z-/Z,E-1,3-dien-1/2-ylboronic ester bearing hydroxyl/amino group.
- Xu, Hua-Dong,Wu, Hao,Jiang, Chun,Chen, Peng,Shen, Mei-Hua
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supporting information
p. 2915 - 2918
(2016/06/14)
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- Lanthanide-Catalyzed Reversible Alkynyl Exchange by Carbon–Carbon Single-Bond Cleavage Assisted by a Secondary Amino Group
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Lanthanide-catalyzed alkynyl exchange through C?C single-bond cleavage assisted by a secondary amino group is reported. A lanthanide amido complex is proposed as a key intermediate, which undergoes unprecedented reversible β-alkynyl elimination followed by alkynyl exchange and imine reinsertion. The in situ homo- and cross-dimerization of the liberated alkyne can serve as an additional driving force to shift the metathesis equilibrium to completion. This reaction is formally complementary to conventional alkyne metathesis and allows the selective transformation of internal propargylamines into those bearing different substituents on the alkyne terminus in moderate to excellent yields under operationally simple reaction conditions.
- Shao, Yinlin,Zhang, Fangjun,Zhang, Jie,Zhou, Xigeng
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supporting information
p. 11485 - 11489
(2016/10/24)
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- PRODUCTION OF OLEFINS FROM A METHANE CONVERSION PROCESS
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Methods and systems are provided for converting methane in a feed stream to acetylene. The method includes the further conversion of the acetylene to a hydrocarbon stream comprising C6 to C12 olefins. The hydrocarbon stream is introduced into a supersonic reactor and pyrolyzed to convert at least a portion of the methane to acetylene. The reactor effluent stream is treated to convert acetylene to another hydrocarbon, and in particular olefins. The method according to certain aspects includes controlling the level of contaminants in the hydrocarbon stream.
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Paragraph 0060
(2015/03/16)
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- PRODUCTION OF OLEFINS FROM A METHANE CONVERSION PROCESS
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Methods and systems are provided for converting methane in a feed stream to acetylene. The method includes the further conversion of the acetylene to a hydrocarbon stream having propylene. The hydrocarbon stream is introduced into a supersonic reactor and pyrolyzed to convert at least a portion of the methane to acetylene. The reactor effluent stream is treated to convert acetylene to another hydrocarbon, and in particular olefins. The method according to certain aspects includes controlling the level of contaminants in the hydrocarbon stream.
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Paragraph 0062; 0063
(2015/03/16)
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