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71.
Florian Blasberg 《Journal of organometallic chemistry》2011,696(23):3593-3600
The synthesis, structural characterization, and coordination behavior of ditopic ortho-hydroquinone-based bis(pyrazol-1-yl)methane ligands (ortho-(OH)2C6H3-4-CHpz2, ortho-(OH)2C6H3-4-CH(3-Phpz)2, and ortho-(OH)2C6H3-4-CH(3-tBupz)2) with pyrazole, 3-phenylpyrazole, and 3-tert-butylpyrazole as donors are described. The reaction of a soluble PdCl2-source with ortho-(OH)2C6H3-4-CHpz2 in acetonitrile yielded the related square-planar N,N-coordinated Pd(II) dichloride complex, whereas treatment of ortho-(OH)2C6H3-4-CH(3-Phpz)2 or ortho-(OH)2C6H3-4-CH(3-tBupz)2 with PdCl2 in acetonitrile resulted in degradation of these ligands. The Pd(II) complexes trans-(3-PhpzH)2PdCl2 and trans-(3-tBupzH)2PdCl2 were isolated and fully characterized including X-ray diffraction analyses. 相似文献
72.
Ke Ding 《Journal of organometallic chemistry》2011,696(23):3662-3667
Reactions of 2-hydroxyphenyl and 2-methoxyphenylbis(pyrazol-1-yl)methanes as well as 2-hydroxyphenyl and 2-methoxyphenylbis(3,5-dimethylpyrazol-1-yl)methanes with W(CO)5THF have been carried out. Heating 2-hydroxyphenylbis(pyrazol-1-yl)methane (L1) with W(CO)5THF in THF at reflux yielded complex (L1)W(CO)4.L1, while similar reaction of 2-hydroxyphenylbis(3,5-dimethylpyrazol-1-yl)methane (L2) with W(CO)5THF resulted in the cleavage of a Csp3-N bond to generate 1,2-bis(2-hydroxyphenyl)-1,2-bis(3,5-dimethylpyrazol-1-yl)ethane (L) and pyrazole derivative W(CO)5(3,5-Me2PzH) (Pz = pyrazol-1-yl). These two fragments were connected together through strong O…H-N and O-H…N hydrogen bonds to form complex L.[W(CO)5(3,5-Me2PzH)]2. The analogous results were observed in the treatment of 2-methoxyphenylbis(pyrazol-1-yl)methane (L3) with W(CO)5THF, which gave product L′.[W(CO)5(PzH)]2 (L′ = 1,2-bis(2-methoxyphenyl)-1,2-bis(pyrazol-1-yl)ethane) as well as certain amount of complex (L3)W(CO)4. In addition, during the reaction of 2-methoxyphenylbis(3,5-dimethylpyrazol-1-yl)methane (L4) with W(CO)5THF, partial decomposition reactions took place to yield complexes (L4)W(CO)4 and W(CO)5(3,5-Me2PzH), but no hydrogen bond was found between these two moieties. 相似文献
73.
A comprehensive kinetic model for oxidative coupling of methane(OCM)over Mn and/or W promoted Na2SO4/SiO2 catalysts was developed based on a micro-catalytic reactor data.The methane conversion and ethylene,ethane,carbon monoxide and carbon dioxide selectivities were obtained in a wide operating condition range of 750 - 825-C,CH4/O2=2.5 - 10 and contact time=267 - 472 kg s m-3.Reaction networks of six models with different rate equation types were compared together.The kinetic rate parameters of each reaction network were estimated using linear regression or genetic algorithm optimization method(GA).A reaction network suggested by Stansch et al.for OCM was found to be the best one and was further used in this work.The suggested model could predict the experimental results of OCM reaction within a deviation range of ± 20%. 相似文献
74.
Chen Li Wendong Wang Congying Xu Yuanxu Liu Bo He Chusheng Chen .CAS Key Laboratory of Materials for Energy Conversion University of Science Technology of China Hefei Anhui China 《天然气化学杂志》2011,(4):345-349
The double perovskite oxides Sr2Mg1-xF exMoO6-δ were investigated as catalysts for the methane oxidation.The structural properties of catalysts were characterized in detail by X-ray diffraction,X-ray photoelectron spectroscopy and X-ray absorption spectroscopy.The catalytic property was strongly influenced by the Fe substitution.The relation between catalytic performance and the degree of Fe substitution was examined with regard to the structure and surface characteristics of the mixed oxides.The Fe-containing catalysts exhibited higher activity attributable to the possible(Fe2+,Mo6+) and (Fe3+,Mo5+)valency pairs,and the highest activity was observed for Sr2Mg0.2Fe0.8MoO6-δ.The enhancement of the catalytic activity may be correlated with the Fe-relating surface lattice oxygen species and was discussed in view of the presence of oxygen vacancies. 相似文献
75.
Methane dehydro-aromatization over Mo/HZSM-5 catalysts in the absence of oxygen: Effect of steam-treatment on catalyst stability 下载免费PDF全文
The effect of steam-treatment to HZSM-5 zeolite and Mo/HZSM-5 with a steaming time range of 0.5-1 h on the catalytic performance of methane dehydro-aromatization (MDA) over Mo/HZSM-5 catalyst prepared with impregnation has been studied in detail in combination with the characterization of 1H MAS NMR technique. Both the deactivation rate constant (kd) and the Brnsted acid sites per unit cell were calculated to quantitatively evaluate the stability of Mo/HZSM-5 catalysts treated with steam at 813 K before and after impregnation of molybdenum species, and the corresponding variation of their Brnsted acid sites. The results reveal that a V-shape relationship between kd and the number of B1 acid sites per unit cell is presented on Mo/HZSM-5 catalyst under the tested steam-treatment and reaction conditions. 相似文献
76.
Molecular dynamics (MD) simulations are performed to study the stability of structure H clathrate-hydrates of methane+large-molecule guest substance (LMGS) at temperatures of 270, 273, 278 and 280 K under canonical (NVT-) ensemble condition in a 3×3×3 structure H unit cell replica with 918 TIP4P water molecules. The studied LMGS are 2-methylbutane (2-MB), 2,3-dimethylbutane (2,3-DMB), neohexane (NH), methylcyclohexane (MCH), adamantane and tert-butyl methyl ether (TBME). In the process of MD simulation, achieving equilibrium of the studied system is recognized by stability in calculated pressure for NVT-ensemble. So, for the accuracy of MD simulations, the obtained pressures are compared with the experimental phase diagrams. Therefore, the obtained equilibrium pressures by MD simulations are presented for studying the structure H clathrate-hydrates. The results show that the calculated temperature and pressure conditions by MD simulations are consistent with the experimental phase diagrams. Also, the radial distribution functions (RDFs) of host-host, host-guest and guest-guest molecules are used to analysis the characteristic configurations of the structure H clathrate-hydrate. 相似文献
77.
Methane reforming With CO2 to syngas over CeO2-promoted Ni/Al2O3-ZrO2 catalysts Prepared Via a direct sol-gel process 下载免费PDF全文
CeO2-promoted Ni/Al2O3-ZrO2 (Ni/Al2O3-ZrO2-CeO2) catalysts were prepared by a direct sol-gel process with citric acid as gelling agent. The catalysts used for the methane reforming with CO2 was studied by infrared spectroscopy (IR), thermal gravimetric analysis (TGA), microscopic analysis, X-ray diffraction (XRD) and temperature-programmed reduction (TPR). The catalytic performance for CO2 reforming of methane to synthesis gas was investigated in a continuous-flow micro-reactor under atmospheric pressure. TGA, IR, XRD and microscopic analysis show that the catalysts prepared by the direct sol-gel process consist of Ni particles with a nanostructure of around 5 nm and an amorphous-phase composite oxide support. There exists a chemical interaction between metallic Ni particles and supports, which makes metallic Ni well dispersed, highly active and stable. The addition of CeO2 effectively improves the dispersion and the stability of Ni particles of the prepared catalysts, and enhances the adsorption of CO2 on the surface of catalysts. The catalytic tests for methane reforming with CO2 to synthesis gas show that the Ni/Al2O3-ZrO2-CeO2 catalysts show excellent activity and stability compared with the Ni/Al2O3 catalyst. The excellent catalytic activity and stability of the Ni/Al2O3-ZrO2-CeO2 are attributed to the highly, uniformly and stably dispersed small metallic Ni particles, the high reducibility of the Ni oxides and the interaction between metallic Ni particles and the composite oxide supports. 相似文献
78.
Ali Morad Rashidi Roghaye Lotfi Amideddin Nouralishahi Mohammad Ali Khodagholi Masoud Zare Faeghe Eslamipour 《天然气化学杂志》2011,20(6):664-668
Nanoporous carbons were synthesized using furfuryl alcohol and sucrose as precursors and MCM-41 and mordenite as nanoporous templates.The produced nanoporous carbons were used as adsorbent for methane storage.The average pore diameter of the samples varied from 3.9 nm to 5.9 nm and the BET surface area varied from 320m2/g to 824m2/g.The volumetric adsorption experiments revealed that MCM-41 and sucrose had better performance compared with mordenite and furfuryl alcohol,correspondingly.Also,the effect of precursor to template ratio on the structure of nanoporous carbons and their adsorption capacities was investigated.The nanoporous carbon produced from MCM-41 mesoporous molecular sieve partially filled by sucrose shows the best methane adsorption capacity among the tested samples. 相似文献
79.
At low temperature of 723 K, methane can be easily activated in the presence of ethylene in the feed, and converted to higher hydrocarbons (C2–C4) and aromatics (C6–C10), through its reaction over rare metals modified Zn/HZSM-5 zeolite catalysts without undesirable carbon oxides formation. Methane can get 37.3% conversion over the above catalysts under low temperature, and the catalysts show a longer lifetime than usual metal supported HZSM-5 zeolite catalysts without adding any rare earth metals. The effects of methane activation over various rare earth metal promoted Zn/HZSM-5 catalysts on the products and influences of several reaction conditions such as temperature, catalyst lifetime and molar ratio of CH4/C2H4 have been discussed. 相似文献
80.