نتایج جستجو برای: α keggin

تعداد نتایج: 165395  

Journal: :Chemical communications 2007
Yang-Guang Li Li-Mei Dai Yong-Hui Wang Xin-Long Wang En-Bo Wang Zhong-Min Su Lin Xu

A new double-Keggin-ion-templated, molybdenum-oxide-based organic-inorganic hybrid compound has been hydrothermally synthesized and its electrocatalytic properties investigated.

Journal: :chemistry of solid materials 2015
m. a. rezvani m. ali nia asli l. abdollahi m. oveisi

mixed-addenda vanadium substituted polyoxometalate supported on anatase tio2 crushed nano leaf was synthesized by an unusual reaction with titanium tetraisopropoxide at 100 ºc via sol–gel method under oil-bath condition. the materials characterized by xrd, tem,  ir and uv–vis  techniques.  in  the  present  work,  efficient  oxidative  of  thiols  with  polyoxometalate-tio2/hydrogen  peroxide  ...

2005
T. Ressler O. Timpe F. Girgsdies J. Wienold T. Neisius

The bulk structural evolution of a vanadium containing heteropolyoxomolybdate (HPOM), H4[PVMo11O40] * 13 H2O, with vanadium substituting for Mo in the Keggin ion was studied under reducing (propene) and partial oxidation reaction conditions (propene and oxygen) by in situ X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) combined with mass spectrometry. During treatment in propene...

Journal: :Physical chemistry chemical physics : PCCP 2011
Laia Vilà-Nadal Scott G Mitchell Antonio Rodríguez-Fortea Haralampos N Miras Leroy Cronin Josep M Poblet

A complimentary combination of Density Functional Theory (DFT) methodology and Electrospray Ionization-Mass Spectrometry (ESI-MS) has been utilized to increase our limited understanding of the first nucleation steps in the formation of the [XM(12)O(40)](n-) Keggin polyoxometalates (POMs) (where addenda metal atom M = W or Mo, and the heteroatom X = P or As). We postulate that the first key step...

Journal: :Chemical communications 2012
Kosei Sugahara Toshihiro Kimura Keigo Kamata Kazuya Yamaguchi Noritaka Mizuno

A tetra-n-butylammonium (TBA) salt of a γ-Keggin -6-charged germanodecatungstate, [γ-H(2)GeW(10)O(36)](6-) (I), could act as an efficient homogeneous catalyst for Knoevenagel condensation of active methylene compounds with carbonyl compounds.

Journal: :Dalton transactions 2015
Aixiang Tian Yali Ning Yang Yang Xue Hou Jun Ying Guocheng Liu Juwen Zhang Xiuli Wang

By using mixed rigid and flexible organic ligands, three Keggin based compounds, [Ag6(tbz)4(bmz)2(H3PW12O40)]·4H2O (1), [Ag(H2bdpm)2(H2PMo12O40)]·7.5H2O (2), and [Ag4(tbz)2(H2bdpm)2(HPMo12O40)]·2H2O (3) (Htbz = thiabendazole, Hbmz = benzimidazole, H2bdpm = 1,1'-bis(3,5-dimethyl-1H-pyrazolate)methane), were hydrothermally synthesized and structurally characterized. Through adopting rigid Htbz li...

2015
Fangli Jing Benjamin Katryniok Franck Dumeignil

When using heteropolycompounds in the selective oxidation of isobutane to methacrolein and methacrylic acid, both the keeping of the primary structure (Keggin units) and the presence of acidic sites are necessary to obtain the desired products. The structural evolution of supported (NH4)3HPMo11VO40 (APMV) catalysts under preliminary thermal oxidizing and reducing treatments was investigated. Va...

Journal: :Dalton transactions 2013
Haijun Pang Carlos J Gómez-García Jun Peng Huiyuan Ma Chunjing Zhang Qingyin Wu

The rational self-assembly of mono-lacunary Keggin clusters with 4d and 4f metal salts via a conventional method has yielded two novel polyoxometalate-based 4d-4f heterometallic compounds containing lacunary Keggin anions connected to ten metal atoms: {[Ag{Ag2(H2O)4}{Ln(H2O)6}2H ⊂ {SiW11Ln(H2O)4O39}2]·nH2O (Ln = Ce and n = 7 for 1, Ln = Pr and n = 3 for 2). Their structures were determined by s...

Journal: :Materials research express 2022

Abstract A series of α -MoO 3 -TiO 2 mixed oxides were prepared by calcining a mixture the heteropolyacid H PMo 12 O 40 and TiO at temperatures ranging from 350 °C to 600 °C. The thus characterized tested for oxidation cyclohexene oxidizing /CO . FTIR XRD characterizations showed that Keggin structure was preserved calcination below 400 Above 450 °C, Keggin’s collapses. analysis revealed as tem...

Journal: :Frontiers in Chemistry 2018

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