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From single-site tantalum complexes to nanoparticles of TaxNy and TaOxNy supported on silica: elucidation of synthesis chemistry by dynamic nuclear polarization surface enhanced NMR spectroscopy and X-ray absorption spectroscopy
- Source :
- Chemical Science. 8:5650-5661
- Publication Year :
- 2017
- Publisher :
- Royal Society of Chemistry (RSC), 2017.
-
Abstract
- Air-stable catalysts consisting of tantalum nitride nanoparticles represented as a mixture of TaxNy and TaOxNy with diameters in the range of 0.5 to 3 nm supported on highly dehydroxylated silica were synthesized from TaMe5 (Me = methyl) and dimeric Ta2(OMe)10 with guidance by the principles of surface organometallic chemistry (SOMC). Characterization of the supported precursors and the supported nanoparticles formed from them was carried out by IR, NMR, UV-Vis, extended X-ray absorption fine structure, and X-ray photoelectron spectroscopies complemented with XRD and high-resolution TEM, with dynamic nuclear polarization surface enhanced NMR spectroscopy being especially helpful by providing enhanced intensities of the signals of 1H, 13C, 29Si, and 15N at their natural abundances. The characterization data provide details of the synthesis chemistry, including evidence of (a) O2 insertion into Ta–CH3 species on the support and (b) a binuclear to mononuclear transformation of species formed from Ta2(OMe)10 on the support. A catalytic test reaction, cyclooctene epoxidation, was used to probe the supported nanoparticles, with 30% H2O2 serving as the oxidant. The catalysts gave selectivities up to 98% for the epoxide at conversions as high as 99% with a 3.4 wt% loading of Ta present as TaxNy/TaOxNy.
- Subjects :
- X-ray absorption spectroscopy
Inorganic chemistry
Tantalum
chemistry.chemical_element
Nanoparticle
02 engineering and technology
General Chemistry
Nuclear magnetic resonance spectroscopy
010402 general chemistry
021001 nanoscience & nanotechnology
01 natural sciences
0104 chemical sciences
Catalysis
chemistry.chemical_compound
Tantalum nitride
chemistry
Cyclooctene
Physical chemistry
0210 nano-technology
Organometallic chemistry
Subjects
Details
- ISSN :
- 20416539 and 20416520
- Volume :
- 8
- Database :
- OpenAIRE
- Journal :
- Chemical Science
- Accession number :
- edsair.doi...........241760869fcd1b206162d316fe96a4dd