نتایج جستجو برای: keggin
تعداد نتایج: 480 فیلتر نتایج به سال:
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...
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...
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...
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.
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.
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.
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.
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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