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1.
Najafpour MM 《Dalton transactions (Cambridge, England : 2003)》2011,40(15):3793-3795
Incorporation of calcium to mixed-valence manganese oxides improved the water oxidation activity of these manganese oxides. 相似文献
2.
Najafpour MM Pashaei B Nayeri S 《Dalton transactions (Cambridge, England : 2003)》2012,41(16):4799-4805
CaMnO(3) and Ca(2)Mn(3)O(8) were synthesized and characterized by SEM, XRD, FTIR and BET. Both oxides showed oxygen evolution activity in the presence of oxone, cerium(IV) ammonium nitrate and H(2)O(2). Oxygen evolution from water during irradiation with visible light (λ > 400 nm) was also observed upon adding these manganese oxides to an aqueous solution containing tris(2,2'-bipyridyl) ruthenium(II), as photosensitizer, and chloro pentaammine cobalt(III) chloride, as electron acceptor, in an acetate buffer. The amounts of dissolved manganese and calcium from CaMnO(3) and Ca(2)Mn(3)O(8) in the oxygen evolving reactions were reported and compared with other (calcium) manganese oxides. Proposed mechanisms of oxygen evolution and proposed roles for the calcium ions are also considered. 相似文献
3.
Gao Z Zhou J Cui F Zhu Y Hua Z Shi J 《Dalton transactions (Cambridge, England : 2003)》2010,39(46):11132-11135
Superparamagnetic mesoporous Mg-Fe bi-metal oxides with varied Mg-Fe atomic ratios have been successfully synthesized as solid base catalysts. The M2F-400 catalyst with Mg/Fe atomic ratio = 2 showed extraordinarily high activities for Knoevenagel reactions even at room temperature. It could be magnetically separated, recycled, and reused for at least five cycles. 相似文献
4.
Nanoscale manganese oxides within Faujasite zeolite have been synthesized with a simple method and characterized by scanning electron microscopy, X-ray diffraction spectrometry, N(2) adsorption-desorption isotherms, transmission electron microscopy, and atomic absorption spectroscopy. These oxides showed efficient water oxidizing activity in the presence of cerium(iv) ammonium nitrate as a non-oxo transfer oxidant. 相似文献
5.
The thermal transformations of the products of hydrous aluminium nitrate hydrolysis in ammonia medium were studied by thermal
analysis, mass spectrometry, infrared spectrophotometry, X-ray phase analysis, and sorption methods. Experiments have shown
that the hydrolysis of hydrous aluminium nitrate in ammonia medium at pH=6-7 leads to the formation of boehmite. The degree
of crystallinity of this product increases, if the hydrolysis is carried out for 264 h at 100°C, with respect the samples
separated from the mother liquor just after completing the dosage of the reagents. It has also been found that aluminium oxide,
obtained by thermal decomposition of the products of hydrolysis carried out for 264 h at an increased temperature, is characterized
by a well developed specific surface, stable at high temperatures, amounting to about 100 m2 g-1, after calcination for 2 h at 1200°C.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
Kang L Zhang M Liu ZH Ooi K 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(3-4):864-869
Four kinds of manganese oxides with either layered or tunnel structures were prepared by different methods. The structural features of the prepared materials were characterized by power X-ray diffraction, IR spectra and SEM observation. A compare analysis of IR spectra for these materials before and after the acid treatment was carried out. Band around 761 cm(-1) could be assigned to a characteristic adsorbent band of tunnel-type manganese oxides; while it was not observed in layer-type manganese oxides. After the acid treatment, the position and relative intensity of the bands in 300-1200 cm(-1) region showed an obvious change for layered manganese oxides in compare with tunnel-type manganese oxides. The variation of IR spectra could be used to distinguish layered manganese oxides from tunnel manganese oxides. 相似文献
7.
Bernet L Lalrempuia R Ghattas W Mueller-Bunz H Vigara L Llobet A Albrecht M 《Chemical communications (Cambridge, England)》2011,47(28):8058-8060
The catalytic water oxidation activity of mononuclear ruthenium complexes comprising a pyridine-functionalized abnormal triazolylidene ligand can be adjusted by modification of the triazolylidene substituents, which is readily achieved through click-type cycloaddition chemistry, affording some of the most active ruthenium catalysts known thus far for water oxidation (TONs > 400, TOFs close to 7000 h(-1)). 相似文献
8.
《Mendeleev Communications》2022,32(2):205-207
Ruthenium(ii) complexes with chelating N-heterocyclic carbene (NHC) ligands were studied in the arylation of phenyl group in 2-phenylpyridine and 1-phenylpyrazole with aryl chlorides in water. Complexes with NHC-ligands containing a hemilabile coordinating N-carboxylatomethyl group enable fast and selective ortho-CH-diarylation in the absence of carboxylate-assisting additives. 相似文献
9.
Summary Iron, aluminium and mixed iron aluminium pillared clays were prepared by partial hydrolysis method and doped with 10% V and Mo. The samples were characterised by XRD, FTIR and surface area and pore volume measurements. Oxidation of cyclohexanol with hydrogen peroxide was done as probe reaction to test catalytic activity. Iron pillared systems exhibited maximum activity. The effects of various reaction variables on the reaction were studied. 相似文献
10.
Najafpour MM Nayeri S Pashaei B 《Dalton transactions (Cambridge, England : 2003)》2011,40(37):9374-9378
A nano-size amorphous calcium-manganese oxide shows efficient water oxidation activity in the presence of cerium(IV) ammonium nitrate. 相似文献
11.
Rueping M Zoller J Fabry DC Poscharny K Koenigs RM Weirich TE Mayer J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(12):3478-3481
Let there be light: A heterogeneous photocatalytic system based on easily recyclable TiO(2) or ZnO allows cross dehydrogenative coupling reactions of tertiary amines. The newly developed protocols have successfully been applied to various C-C and C-P bond-forming reactions to provide nitro amines as well as amino ketones, nitriles and phosphonates. 相似文献
12.
Studies have been made of the effects of mixtures of aluminium oxides and organic halogen compounds on the flammability of polyethylene and an acrylonitrile-butadiene-styrene copolymer (ABS). There is considerable synergism in the flame-retardant action, particularly when anhydrous alumina and a bromine compound are introduced into ABS. The addition of relatively small amounts of alumina prevents the saturation effects otherwise observed when increasing quantities of halogen compounds on their own are incorporated into the polymers. Chemical interaction between aluminium oxides and the halogens occurs in the condensed phase. 相似文献
13.
《Surface and interface analysis : SIA》2018,50(7):734-743
Metal oxides have only recently begun to be used as catalysts for the growth of carbon nanotubes. Here, we propose a new model for the growth of carbon nanotubes, based on the intra‐granular charge transfer transition and the lattice strain of the catalyst nanoparticles. This is supported by results obtained from the doped metal oxides like samarium doped zinc oxide (SmZnO) and terbium doped zinc oxide (TbZnO). The intragranular charge transfer transition is believed to be responsible for the dissociation of the hydrocarbon molecules. The lattice strain of the catalyst nanoparticles appears to be responsible for the diffusion of carbon atoms through the catalyst particles. 相似文献
14.
Christelle Freund Author VitaeAuthor Vitae Fritz E. Kühn Author Vitae 《Journal of organometallic chemistry》2006,691(18):3718-3729
Monomeric cyclopentadiene molybdenum oxides were among the first synthesized high oxidation state organometallics. However, their syntheses and applications have long been overshadowed by their rhenium(VII) congeners, in particular by (pentamethylcyclopentadienyl)trioxorhenium(VII) and methyltrioxorhenium(VII). Only during the last decade a renaissance of the cyclopentadienyl molybdenum oxides is starting. Both with respect to synthetic access ways and to applications as oxidation catalysts in homogeneous and heterogeneous phase the interest in cyclopentadienyl molybdenum oxides and their tricarbonyl precursors is increasing. This results from the usually time-easy and straightforward synthetic procedures leading to these compounds and their easy heterogenizability, both on mesoporous materials and in ionic liquids. The catalytic performance, especially in olefin epoxidation with tert-butylhydroperoxide being the oxidant is very good and the derivatization to reach taylor made catalysts seems to be much easier than in the case of the organorhenium oxides. Another advantage in comparison to the latter complexes is the possible presence of two organic functionalities, which can be independently modified, e.g. for heterogenization of the complexes and for the enhancing of their catalytic activity at the same time. 相似文献
15.
Oxides of transition metals could be suitable alternatives to catalysts based on noble metals in the oxidation processes used
for the abatement of volatile organic compounds. Mixed oxides of transition metals can exhibit good efficiency and thermal
stability, as well as being inexpensive. In this work, oxide catalysts containing various combinations of Cu, Co, Ni, Mn,
and Al, grained or supported on oxidised aluminium foil Al2O3/Al, were studied in terms of their chemical and physical properties, including their chemical composition, porous structure,
phase composition, reducibility, and activity in total ethanol oxidation. Ternary co-precipitated catalysts in the form of
grains obtained from layered double hydroxide-like precursors were highly active, especially those containing manganese. Deposition
of the selected precursors on an anodised aluminium foil-support afforded less active catalysts, mainly because the required
metal molar ratios were not achieved, and insufficient amounts of metals were deposited. However, by controlling the preparation
conditions (pH), higher loading of active components and higher catalytic activity were obtained. 相似文献
16.
17.
Chen C Xu J Zhang Q Ma Y Zhou L Wang M 《Chemical communications (Cambridge, England)》2011,47(4):1336-1338
A new type of superhydrophobic material, FP-Co-SiO(2) was prepared with organic groups immobilized on the surface of the SiO(2)-based nanocomposite. This material showed much higher catalytic activity for selective oxidation of hydrocarbons than an equivalent hydrophilic catalyst. 相似文献
18.
Phosphine oxides were found to be efficient neutral coordinate-organocatalysts (NCOs) for the allylation of N-acylhydrazones. Among the phosphine oxides tested, a three carbon-tethered bisphosphine oxide (dppp dioxide) was found to be the most effective, and in the presence of dppp dioxide, less reactive aromatic and [small alpha],[small beta]-unsaturated N-acylhydrazones underwent allylation as well as diastereoselective crotylation. Furthermore, a polymer-supported phosphine oxide was also developed as an effective immobilized NCO. 相似文献
19.
Tertiary amine oxides catalyze a variety of phase transfer reactions, primarily by deoxygenation to form the tertiary amine or derived catalyst. 相似文献
20.
Xian Wu 《Journal of organometallic chemistry》2011,696(25):4147-4151
The tungsten neopentylidyne complexes [Me3CCW(NPR3){OCMe(CF3)2}2] (3a, R = Cy; 3b, R = iPr) were prepared in excellent yields by the reaction of the solvate complex [Me3CCW{OCMe(CF3)2}3(DME)] (DME = 1,2-dimethoxyethane) with equimolar amounts of the corresponding phosphoraneiminato lithium species R3PNLi (R = Cy, iPr) at room temperature. The products were characterized by 1H, 13C{1H}, 19F{1H} and 31P{1H} NMR spectroscopy and elemental analysis. Single crystals of both complexes were obtained from diethyl ether solutions at −35 °C, and the molecular structures were determined by X-ray diffraction analysis. Complexes 3a and 3b are able to efficiently catalyse alkyne cross-metathesis (ACM) of 3-pentynyl benzyl ether (4) and ring-closing alkyne metathesis (RCAM) of bis(3-pentynyl)adipate (6) at room temperature and with low catalyst loadings (1 or 2 mol%) to afford the diether 5 and the cyclic diester 7 in virtually quantitative yields. The reactions were carried out in the presence of molecular sieve 5 Å to adsorb 2-butyne during the metathesis. 相似文献