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81.
B. P. Tarasov V. N. Fokin A. P. Moravskii Yu. M. Shul’ga 《Russian Chemical Bulletin》1997,46(4):649-652
Fullerene hydrides containing 24–26 H atoms per fullerene molecule were obtained by hydrogenation of solid-phase mixtures
of fullerenes with either intermetallic compounds LaNi5, LaNi4.65Mn0.35, CeCo3 or V and Pd metals with gaseous hydrogen at 1.0–2.5 MPa and 573–673 K. These fullerene hydrides decompose at 800 K with evolution
of H2. Upon subsequent heating to 1000 K, vanadium reacts with fullerene to yield a cubic phase of vanadium carbide. The intermetallic
compounds react with fullerene with the formation of a metallic phase of the 3d-metal and destruction of fullerene. Palladium
does not react with fullerene.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 679–683, April, 1997. 相似文献
82.
Enantiomerically pure iridium complexes with phosphino‐ and (phosphinooxy)‐substituted N‐heterocyclic carbene (NHC) ligands were synthesized. Investigation of their electronic properties showed a similar trans influence of the phosphino (or phosphinooxy) and the NHC units. The complexes were tested in iridium‐catalyzed hydrogenation. While low conversions were observed with unfunctionalized olefins, the catalysts proved to be suitable for hydrogenation of the α,β‐unsaturated ester 20 , allylic alcohol 21 , and imine 22 . The enantioselectivities were, however, moderate. 相似文献
83.
Summary Single reverse water-gas shift (RWGS) and dehydrogenation of propane with CO2(DH-CO2) reactions in the presence and absence of the CrOx/SiO2 catalyst have been studied between 673 and 873 K. It was found that the CrOx/SiO2 catalyst is active both in the dehydrogenation of propane and in the RWGS reactions. The obtained results suggest that the
dehydrogenation of propane to propene in the presence of CO2on CrOx/SiO2can be facilitated by the RWGS reaction.</o:p> 相似文献
84.
85.
Sol-gel Cu//MgOSiO2 catalysts were prepared gelling tetraethoxysilane (TEOS), magnesium ethoxide and copper acetylacetonate at pH 3 and pH 9. The catalysts shown specific surface areas ca. 500 m2/g and 140 m2/g for pH 9 and pH 3 preparations respectively. Si(OH) and Si(OH)2 hydroxy groups were observed by MAS-RMN spectroscopy in both preparations. CO2-TPD and NH3-TPD desorption thermograms showed that acid and basic sites were formed on the catalysts surface. It has been found that the catalysts having the highest density of basic sites were the catalysts showing the highest activity for the CO oxidation. It is proposed that the catalytic activity depends of the relative Cu=1/Cu=2 stability given by the support acidity. 相似文献
86.
Fonseca GS Umpierre AP Fichtner PF Teixeira SR Dupont J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(14):3263-3269
Stable transition-metal nanoparticles of the type [M(0)](n) are easily accessible through the reduction of Ir(I) or Rh(III) compounds dissolved in "dry" 1-n-butyl-3-methylimidazolium hexafluorophosphate ionic liquid by molecular hydrogen. The formation of these [M(0)](n) nanoparticles is straightforward; they are prepared in dry ionic liquid whereas the presence of the water causes the partial decomposition of ionic liquid with the formation of phosphates, HF and transition-metal fluorides. Transmission electron microscopy (TEM) observations and X-ray diffraction analysis (XRD) show the formation of [Ir(0)](n) and [Rh(0)](n) nanoparticles with 2.0-2.5 nm in diameter. The isolated [M(0)](n) nanoparticles can be redispersed in the ionic liquid, in acetone or used in solventless conditions for the liquid-liquid biphasic, homogeneous or heterogeneous hydrogenation of arenes under mild reaction conditions (75 degrees C and 4 atm). The recovered iridium nanoparticles can be reused several times without any significant loss in catalytic activity. Unprecedented total turnover numbers (TTO) of 3509 in 32 h, for arene hydrogenation by nanoparticles catalysts, have been achieved in the reduction of benzene by the [Ir(0)](n) in solventless conditions. Contrarily, the recovered Rh(0) nanoparticles show significant agglomeration into large particles with a loss of catalytic activity. The hydrogenation of arenes containing functional groups, such as anisole, by the [Ir(0)](n) nanoparticles occurs with concomitant hydrogenolysis of the C-O bond, suggesting that these nanoparticles behave as "heterogeneous catalysts" rather than "homogeneous catalysts". 相似文献
87.
硼掺杂还原态氧化石墨烯催化剂的制备及其蒽催化加氢性能的研究 《燃料化学学报》2003,48(8):1004-1014
制备了一系列硼掺杂的还原氧化态石墨烯催化剂并应用于蒽加氢反应。结果表明,随着催化剂处理温度的升高,催化剂中有序碳结构会发生变化,硼会取代材料骨架中的碳,进而影响蒽和氢气的吸附活化。经硼改性后,催化剂对蒽加氢反应表现出了很高的加氢活性,蒽的最高转化率可达97%,深度加氢产物八氢蒽的最高选择性可达19%。 相似文献
88.
89.
Marit Rolandsgard 《Tetrahedron》2005,61(16):4129-4140
Preparation of α-oxo derivatives of spiro[4.4]nonane, spiro[4.5]decane and spiro[5.5]undecane derivatives is described. An efficient method for spiroannulation by Rh(I)-catalysed intramolecular hydroacylation provides α,α′-difunctionalised spiro[4.5]decanes. The α,α′-dioxo groups have been converted into vinyl triflates for arylation by Pd-catalysed cross-coupling reactions under Stille, Negishi or Suzuki conditions depending on relative reactivities. Stereoselective saturation of the conjugated aryl olefinic bonds by catalytic hydrogenation over Pd-carbon provides methodology for stereoselective preparation of α-aryl- and α,α′-cis,cis-diaryl spiranes, the latter with a sandwich like structure. Single crystal X-ray analyses have been used in the structural assignments. 相似文献
90.
Muliadi Ramli Nasrullah Idris Kenichi Fukumoto Hideaki Niki Fujio Sakan Tadashi Maruyama Koo Hendrik Kurniawan Tjung Jie Lie Kiichiro Kagawa 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007,62(12):1379-1389
A TEA CO2 laser (350 mJ–1.5 J, 10.6 μm, 200 ns, 10 Hz) was focused onto a metal sub-target under He as host gas at 1 atmospheric pressure with a small amount of impurity gas, such as water and ethanol vapors. It was found that the TEA CO2 laser with the help of the metal sub-target is favorable for generating a strong, large volume helium gas breakdown plasma at 1 atmospheric pressure, in which the helium metastable-excited state was then produced overwhelmingly. While the metal sub-target itself was never ablated. The helium metastable-excited state produced after the strong helium gas breakdown plasma was considered to play an important role in exciting the atoms. This was confirmed by the specific characteristics of the detected H emission, namely the strong intensity with low background, narrow spectral width, and the long lifetime. This technique can be used for gas and solid samples analysis. For nonmetal solid analysis, a metal mesh was introduced in front of the nonmetal sample surface to help initiation of the helium gas breakdown plasma. For metal sample, analysis can be carried out by combining the TEA CO2 laser and an Nd–YAG laser where the Nd–YAG laser is used to ablate the metal sample. The ablated atoms from the metal sample are then sent into the region of helium gas breakdown plasma induced by the TEA CO2 laser to be excited through the helium metastable-excited state. This technique can be extended to the analysis of other elements, not limited only to hydrogen, such as halogens. 相似文献