TY - JOUR

T1 - Heterolytic alkene oxidation with H2O2catalyzed by Nb-substituted Lindqvist tungstates immobilized on carbon nanotubes

AU - Evtushok, Vasiliy Yu

AU - Ivanchikova, Irina D.

AU - Lopatkin, Vladimir A.

AU - Maksimchuk, Nataliya V.

AU - Podyacheva, Olga Yu

AU - Suboch, Arina N.

AU - Stonkus, Olga A.

AU - Kholdeeva, Oxana A.

N1 - Funding Information: The authors thank Dr. M. V. Shashkov for GC–MS measurements. This work was supported by the Russian Foundation for Basic Research (grant no. 19-03-00172) and the Ministry of Science and Higher Education of the Russian Federation within the governmental order for Boreskov Institute of Catalysis (project AAAA-A21-121011390008-4). The studies were carried out using facilities of the shared research center “National center of investigation of catalysts” at Boreskov Institute of Catalysis. Publisher Copyright: © The Royal Society of Chemistry. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/5/7

Y1 - 2021/5/7

N2 - Nb-Monosubstituted polyoxometalates (Nb-POM) of the Lindqvist structure, monomers [Nb(L)W5O19]n- (Nb(L)W5, L = O, OCH3, (O)2; n = 3 or 2) and a dimer [(NbW5O18)2O]4-, were successfully immobilized on N-free and N-doped carbon nanotubes (CNTs and N-CNTs) and characterized by elemental analysis, N2 adsorption, XPS, FTIR spectroscopy, HR-TEM, and HAADF-STEM. The supported catalysts revealed superior activity and selectivity for the heterolytic oxidation of alkenes with aqueous hydrogen peroxide as a green oxidant to produce epoxides and diols as the principal oxidation products. Both CNTs and N-CNTs stabilize the monomeric form [Nb(OH)W5O18]2-, preventing its deactivation through dimerization and thereby leading to a great increase in the catalyst activity and productivity relative to homogeneous Nb(L)W5. Although N-doping ensures a more homogeneous dispersion of Nb-POMs on the surface, it enhances unproductive decomposition of the oxidant, leading to the enhancement of homolytic oxidation routes. The elaborated Nb-POM/CNT catalysts reveal the truly heterogeneous nature of the catalysis, and can be easily recovered by filtration, regenerated, and reused several times without a significant loss of the catalytic performance.

AB - Nb-Monosubstituted polyoxometalates (Nb-POM) of the Lindqvist structure, monomers [Nb(L)W5O19]n- (Nb(L)W5, L = O, OCH3, (O)2; n = 3 or 2) and a dimer [(NbW5O18)2O]4-, were successfully immobilized on N-free and N-doped carbon nanotubes (CNTs and N-CNTs) and characterized by elemental analysis, N2 adsorption, XPS, FTIR spectroscopy, HR-TEM, and HAADF-STEM. The supported catalysts revealed superior activity and selectivity for the heterolytic oxidation of alkenes with aqueous hydrogen peroxide as a green oxidant to produce epoxides and diols as the principal oxidation products. Both CNTs and N-CNTs stabilize the monomeric form [Nb(OH)W5O18]2-, preventing its deactivation through dimerization and thereby leading to a great increase in the catalyst activity and productivity relative to homogeneous Nb(L)W5. Although N-doping ensures a more homogeneous dispersion of Nb-POMs on the surface, it enhances unproductive decomposition of the oxidant, leading to the enhancement of homolytic oxidation routes. The elaborated Nb-POM/CNT catalysts reveal the truly heterogeneous nature of the catalysis, and can be easily recovered by filtration, regenerated, and reused several times without a significant loss of the catalytic performance.

UR - http://www.scopus.com/inward/record.url?scp=85106056646&partnerID=8YFLogxK

U2 - 10.1039/d1cy00153a

DO - 10.1039/d1cy00153a

M3 - Article

AN - SCOPUS:85106056646

VL - 11

SP - 3198

EP - 3207

JO - Catalysis Science and Technology

JF - Catalysis Science and Technology

SN - 2044-4753

IS - 9

ER -