نتایج جستجو برای: keggin

تعداد نتایج: 480  

Journal: :Catalysts 2021

Selective oxidation of isobutane to methacrolein (MAC) and methacrylic acid (MAA) has received great interest both in the chemical industry academic research. The advantages this reaction originate not only from low cost starting material reduced process complexity, but also limiting use toxic reactants production wastes. Successive studies reports have shown that heteropolycompounds (HPCs) wit...

نجفی, عاطفه, میرزائی, مسعود ,

Hybrid inorganic-organic material based on Keggin type polyoxometalaes ([SiW12O40]4-) and praseodymium-dipicolinic acid (pydc; 2,6-pyridindicarboxylic acid) with the formula of [Pr2(pydc)2(H2O)8][H2SiW12O40]•4H2O (1) is obtained under a hydrothermal condition. Compound 1 was characterized by infrared spectrum and elemental analysis and its structure was further determined by single-crystal X-ra...

The hydrothermal synthesis of two new inorganic-organic hybrid materials in which PDA (PDA = 1,10-phenanthroline-2,9-dicarboxylate) is connected to a well-defined Keggin-type polyoxometalate anion (POM) and a Ln(III) cation (POM = [SiW12O40]4−; Ln = Eu3+ (1), Er3+ (2)), are reported. These hybrids are characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction. Single-c...

Journal: :Inorganic chemistry frontiers 2023

Transition-metal substituted Keggin-type polyoxometalates (POMs) are of great interest for applications in biomedicine, material science and catalysis. The synthesis transition metal-substituted polytungstates via the formation a lacunary...

Journal: :Chemical communications 2009
Miao Sun Jizhe Zhang Qinghong Zhang Ye Wang Huilin Wan

A Keggin-type polyoxometalate (Cs(1.5)H(1.5)PW(12)O(40))-supported Pd catalyst is efficient for the direct synthesis of H(2)O(2) from H(2) and O(2) in the absence of any acid or halide additives under atmospheric pressure.

Journal: :Dalton transactions 2014
Yang Chen Elzbieta Trzop Anna Makal Yu-Sheng Chen Philip Coppens

A large manganese-doped polyoxotitanate nanocluster Ti28MnO38(OEt)40H2, has been synthesized solvothermally. Its structure is arranged around the four-coordinate Mn(2+) dopant atom in a Keggin-type structure. A significant reduction of the band gap relative to that of undoped polyoxotitanate clusters is observed.

Journal: :Chemical communications 2011
Jana Juan-Alcañiz Maarten Goesten Alberto Martinez-Joaristi Eli Stavitski Andrei V Petukhov Jorge Gascon Freek Kapteijn

The templating effect of the Keggin polyanion derived from phosphotungstic acid (PTA) during the synthesis of NH(2)-MIL-101(Al) has been investigated by means of in situ SAXS/WAXS. Kinetic analysis and structural observations demonstrate that PTA acts as a nucleation site and that it stabilizes the precursor phase NH(2)-MOF-235(Al). Surprisingly kinetics of formation are little changed.

Journal: :Chemical communications 2011
Mi Liu Weiping Deng Qinghong Zhang Yanliang Wang Ye Wang

Ru nanoparticles loaded on a Keggin-type polyoxometalate (Cs(3)PW(12)O(40)), which did not possess strong intrinsic acidity, efficiently catalysed the conversions of cellobiose and cellulose into sorbitol in water medium in H(2) at ≤433 K. The Brønsted acid sites generated in situ from H(2) have been demonstrated to play a key role in the formation of sorbitol.

Journal: :Molecules 2010
Rachedine Kaoua Norah Bennamane Saliha Bakhta Sihame Benadji Cherifa Rabia Bellara Nedjar-Kolli

An efficient and improved procedure for the synthesis of 1,4-diazepine and 1,5-benzodiazepine derivatives via the reaction of ketimine intermediates with aldehydes in the presence of Keggin-type heteropolyacids (HPAs) was developed. High yields and short reaction times were obtained for both electron-releasing and electron-withdrawing substituted 1,4-diazepine  and 1,5-benzodiazepines derivatives.

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