107-83-5Relevant articles and documents
Catalytic consequences of hydroxyl group location on the kinetics of n-hexane hydroisomerization over acidic zeolites
Chiang, Hsu,Bhan, Aditya
, p. 98 - 107 (2011)
The measured kinetics of n-C6H14 hydroisomerization reactions is consistent with a bifunctional mechanism involving the facile dehydrogenation of n-hexane on the metal catalyst and a kinetically relevant step involving isomerization of n-hexene on zeolitic acidic sites. The measured activation entropy in small 8-MR pockets of MOR (-35 J mol-1 K -1) is similar to that in larger 12-MR channels of MOR (-37 J mol-1 K-1) and BEA (-33 J mol-1 K-1) but higher than that in medium pore FER (-86 J mol-1 K -1), suggesting that partial confinement of C6 olefinic reactants results in lower free energy for the isomerization reaction in 8-MR pockets of MOR. The hypothesis that a cyclopropane-like cationic transition state is not completely contained within the 8-MR pockets of MOR is consistent with the observed selectivity to 2-methylpentane and 3-methylpentane in the 8-MR pockets being identical to that measured in larger 12-MR channels of MOR and BEA. The lower activation energy measured in 8-MR pockets compared to larger 12-MR channels of MOR may arise due to greater electrostatic stabilization of the positively charged transition state by framework oxygen atoms located on the pore mouth of the smaller 8-MR pockets of MOR or due to the larger heat of adsorption caused by confinement in smaller 8-MR pockets. The lower activation energy in 8-MR channels and comparable loss in entropy mediated by partial confinement results in the rate per proton in 8-MR pockets being five times larger than the rate in 12-MR channels of MOR. These results provide another conceptual consideration for rigorous and quantitative understanding of local environment effects of zeolite channel size and connectivity on the rate and selectivity of acid-catalyzed reactions.
Comparative studies on enzyme activity of immobilized horseradish peroxidase in silica nanomaterials with three different shapes and methoxychlor degradation of vesicle-like mesoporous SiO2 as carrier
Yang, Yuxiang,Zhao, Min,Yao, Pingping,Huang, Yan,Dai, Zuocheng,Yuan, Hongming,Ni, Chaoying
, p. 2971 - 2978 (2018)
In the present work, three differently shaped mesoporous silica nanoparticles, spherical nano-SiO2, tubular mesoporous SiO2 and vesicle-like mesoporous SiO2 (VSL), were prepared and used to immobilize Horse radish peroxida
Spectroscopic characterization-catalytic activity correlation of molybdena based catalysts
Al-Kandari,Mohamed,Al-Kandari,Al-Kharafi,Mekhemer,Zaki,Katrib
, p. 1 - 8 (2013)
Titania-supported molybdena catalyst was prepared by calcination at 773 K of ammonium heptamolybdate-impregnated TiO2 pellets with the equivalent of 5 monolayers of MoO3. Then, potassium-modified versions of the catalyst were prepared at 0.5-5 wt%-K. The modified and unmodified catalysts were characterized, before and after H2-reduction at 673 K, by means of ISS, XPS, UPS and FT-IR spectroscopy techniques. Results obtained enabled revealing the presence of density of states (DOS) at the Fermi level and, hence, metallic properties related to the deformed rutile structure of MoO2. On the other hand, Br?nsted (MoOH) acidic function was found to form on the surface of the MoO2 structure, thereby producing a metal-acid (bifunctional) MoO2-x(OH)y catalyst. The presence of Br?nsted acid MoOH groups was evidenced by in situ IR spectra of adsorbed pyridine molecules. On the other hand, the K-modification was found to enhance the molybdena dispersity and reducibility, but to suppress the surface acidity by transforming the bifunctional MoO2-x(OH) y species into the monofunctional MoO2-x(OK)y species. Subsequent catalytic measurements employing hydrotreating reactions of 1-hexene and n-hexane could confirm the exposure of bifunctional or monofunctional sites on the catalysts tested. The combination of research methods adopted in the present investigation has shown competency in unravelling the nature of active sites on heterogeneous catalysts.
Effective n-octane isomerization under exceptionally mild conditions using a novel class of superacidic ionic liquids
Meyer, Carolin,Wasserscheid, Peter
, p. 7625 - 7627 (2010)
Superacidic chloroaluminate ionic liquids of the general formula [cation]Cl/AlCl3[X(AlCl3) > 0.5] + H2SO 4 effectively isomerize n-octane to form branched liquid hydrocarbon isomers. Due to the highly acidic character of the ionic liquid the reaction proceeds under extremely mild conditions in a liquid-liquid biphasic reaction mode leading to a minimum of undesired cracking side-reactions.
Ionic Hydrogenations using Transition Metal Hydrides. Rapid Hydrogenation of Hindered Alkenes at Low Temperature
Bullock, R. Morris,Rappoli, Brian J.
, p. 1447 - 1448 (1989)
Tetra-substituted, tri-substituted, and 1,1-disubstituted alkenes can be rapidly hydrogenated in high yield at -75 deg C using CF3SO3H/HMo(CO)3(C5H5) or CF3SO3H/HSiEt3
OSMIUM LIQUID-PHASE CATALYSTS FOR HYDROGENOLYSIS OF SATURATED HYDROCARBONS AND HYDROGENATION OF ARENES
Akhrem, I. S.,Reznichenko, S. V.,Grushin, V. V.,Simonova, O. Yu.,Christovalova, N. M.,Vol'pin, M. E.
, p. 2229 - 2233 (1989)
Reduction of OsO4 by molecular hydrogen in alkane (cycloalkane) or benzene (toluene) solution produces small-lagand clusters of osmium of composition Os1.5-2.5CH0-2 with a particle size 10-40 Angstroem and a specific surface area of 34-46 m2/g.Hydrogenation of dry catalyst produces methane.The small-ligand osmium clusters obtained effectively catalyze hydrogenolysis of alkanes and cycloalkanes at 100-150 deg C and PH2 = 5 MPa and hydrogenation of benzene at 20 deg C and PH2 = 0.1 MPa.
ETUDE DE L'ISOMERISATION DU METHYL-4 PENTENE-1 PAR L'HYDRIDO DIAZOTE TRIS(TRIPHENYLPHOSPHINE)COBALT(I): CoHN2(PPh3)3
Petit, F.,Arzouyan, C.,Peiffer, G.,Gaydou, E.
, p. 261 - 272 (1981)
At 25 deg C, and under 1 to 7 bar nitrogen pressure, the isomerization of 4-methyl-1-pentene catalyzed in benzene by CoHN2(PPh3)3 involves two active species: HCoN2(S1)(PPh3)2 and HCo(S1)(PPh3)3, respectively, in greater quantities at higher (P(N2) > 7 bars) and small quantities at P(N2) - O nitrogen pressures. The kinetic study shows that the rate of the reaction is always ruled by the equation:
High yield of renewable hexanes by direct hydrolysis-hydrodeoxygenation of cellulose in an aqueous phase catalytic system
Liu, Yong,Chen, Lungang,Wang, Tiejun,Zhang, Xinghua,Long, Jinxing,Zhang, Qi,Ma, Longlong
, p. 11649 - 11657 (2015)
In aqueous phosphoric acid, cellulose was efficiently converted into hexanes using a Ru/C catalyst combined with layered compounds or silica-alumina materials. In this process, the direct production of hexanes from cellulose can be improved by suppressing the formation of isosorbide, which makes it difficult to yield hexanes by further hydrodeoxygenation. As the co-catalyst, layered compounds showed a significant inhibition effect on the formation of isosorbide from sorbitol due to the steric restrictions of sorbitol dehydration within the interlayers of layered compounds. Typically, layered LiNbMoO6 played a great role in promoting the production of hexanes directly from cellulose and a promising yield (72% carbon mol) of hexanes was obtained. In addition, the protonic acid, H3PO4, offered efficient catalysis for the hydrolysis of cellulose and the dehydration of the sorbitol hydroxyl moiety.
Transformations of n-Hexane over EUROPT-1: Fragments and C6 Products on Fresh and Partially Deactivated Catalyst
Paal, Zoltan,Groeneweg, Helga,Paal-Lukacs, Julia
, p. 3159 - 3166 (1990)
The reactions of n-hexane have been studied on 6.3percent Pt/SiO2 (EUROPT-1) at different hydrogen and n-hexane pressures, and at 543-633 K, over fresh catalyst and over catalysts deactivated by long runs.Turnover numbers are compared with literature data: the differences are attributed to hydrogen pressure effects.Deactivation influences first of all, selectivity.In addition, the 'depth' and 'pattern' of hydrogenolysis have been determined.At low temperature multiple splitting seems to be favoured.Isomerization gives predominantly 3-methylpentane.At medium temperatures, isomerization, C5-cyclization and internal splitting prevall; their ratio is controlled by the hydrogen pressure.The ratio of 2-methylpentane to 3-methylpentane is related to the ratio of internal to terminal rupture.Terminal splitting prevails at highest temperature.Aromatization increases with temperature but seems to be independent of the other reactions.The results are interpreted in terms of three different surface states.These correspond to Pt-H, Pt-C-H and Pt-C under increasing severity of conditions.
Optimization of manganese content by high-throughput experimentation of Pt/WOx-ZrO2-Mn catalysts
Hernandez-Pichardo,Fuente, J.A. Montoya de la,Angel, P. del,Vargas,Hernández,González-Brambila
, p. 408 - 413 (2010)
A library of Pt/WOx-ZrO2-Mn catalysts was developed in order to optimize the manganese content in this catalytic system for the isomerization of n-hexane. The catalysts were synthesized, characterized and screened using high-throughput experimentation (HTE) techniques. The catalysts were prepared by surfactant-assisted coprecipitation whereas the characterization was done by X-ray diffraction (XRD), Raman and UV-vis spectroscopy. For this second screening, several catalysts with different manganese contents were prepared; it was found that the incorporation of Mn modifies the anchorage of tungsten on the zirconia surface, thus improving its catalytic properties, in terms of the n-hexane conversion and selectivity, depending on the catalyst composition. These results suggest that this methodology allows the optimization of manganese and tungsten contents on these solid catalysts.
