Nitrogen-Doped Carbon Nanotubes as an Effective Support
of Heterogeneous Catalysts for Selective Alkene Oxidation1
A. N. Subocha, *, V. Yu. Evtushoka, L. S. Kibisa, O. A. Kholdeevaa, and O. Yu. Podyachevaa
a Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Correspondence to: *e-mail: arina@catalysis.ru
1Abbreviations and designations: CNTs, carbon nanotubes; N‑CNTs, nitrogen-containing carbon nanotubes; POMs, polyoxometallates; PW4, the tetranuclear phosphotungstate [PO4{WO(O2)2}4]3–; NPy, NPyr, NQ, and NOx, pyridine-like, pyrrole, graphite-like, and oxidized structural positions, respectively; TG, thermogravimetry; DTA, differential thermal analysis; DSC, differential scanning calorimetry; TPO, temperature-programmed oxidation; XPS, X-ray photoelectron spectroscopy.
Received 15 June, 2020
Abstract—Nitrogen-doped carbon nanotubes (N-CNTs) with different degrees of nitrogen doping were synthesized. The effects of nitrogen in the N-CNTs on the hydrophilic–hydrophobic properties of carbon nanotubes and their activity in the decomposition of Н2О2 were studied. Various approaches to the surface modification of N-CNTs by alkyl groups were studied, and the high resistance of N-CNTs to alkylation was found. Heterogeneous catalysts based on the polyoxometallate [PO4{WO(O2)2}4]3– and N-CNTs with a low degree of nitrogen doping (≤1.8 at %) were successfully synthesized. The high efficiency of the catalysts in the liquid-phase reactions of selective oxidation of alkenes using H2O2 as a green oxidizer was found, and the heterogeneous nature of catalysis was confirmed.
Keywords: carbon nanotubes, nitrogen doping, polyoxometallates, alkenes, liquid-phase oxidation
DOI: 10.1134/S0023158421020105