Research output: Contribution to journal › Article › peer-review
Mesoporous niobium-silicates prepared by evaporation-induced self-assembly as catalysts for selective oxidations with aqueous H2O2. / Ivanchikova, Irina D.; Maksimchuk, Nataliya V.; Skobelev, Igor Y. et al.
In: Journal of Catalysis, Vol. 332, 01.12.2015, p. 138-148.Research output: Contribution to journal › Article › peer-review
}
TY - JOUR
T1 - Mesoporous niobium-silicates prepared by evaporation-induced self-assembly as catalysts for selective oxidations with aqueous H2O2
AU - Ivanchikova, Irina D.
AU - Maksimchuk, Nataliya V.
AU - Skobelev, Igor Y.
AU - Kaichev, Vasily V.
AU - Kholdeeva, Oxana A.
PY - 2015/12/1
Y1 - 2015/12/1
N2 - Hydrothermally stable mesoporous niobium-silicates Nb-MMM-E have been first prepared following the convenient and versatile evaporation-induced self-assembly (EISA) methodology. The new materials have been characterized by elemental analysis, XRD, low-temperature N2 adsorption, SEM, XPS, DRS UV-vis, and Raman techniques. DR UV-vis spectroscopy enabled differentiation between isolated and oligomerized Nb centers on the silica surface. Use of niobium(V) ethoxide modified with acetylacetone (acac) as a Nb source favored the formation of dimeric and/or small oligomeric Nb centers on the surface of mesoporous silica while ammonium niobate(V) oxalate coupled with acac gave mostly site-isolated Nb species. The Nb-MMM-E materials catalyzed selectively oxidation of various unsaturated compounds of interest for fine and specialty chemistry using the green oxidant - aqueous hydrogen peroxide. Epoxidation of both electron rich and electron deficient C=C bonds could be accomplished over Nb-MMM-E. While catalysts with isolated Nb centers were preferable for the selective formation of epoxides sensitive to ring opening and overoxidation, both single site and oligomerized Nb centers were equally effective for the production of relatively stable epoxides. The truly heterogeneous nature of the catalysis over Nb-MMM-E and absence of Nb leaching into solution have been proved by hot filtration tests coupled with elemental analysis. The catalysts could be easily recovered by filtration and reused several times without significant deterioration of the catalytic performance.
AB - Hydrothermally stable mesoporous niobium-silicates Nb-MMM-E have been first prepared following the convenient and versatile evaporation-induced self-assembly (EISA) methodology. The new materials have been characterized by elemental analysis, XRD, low-temperature N2 adsorption, SEM, XPS, DRS UV-vis, and Raman techniques. DR UV-vis spectroscopy enabled differentiation between isolated and oligomerized Nb centers on the silica surface. Use of niobium(V) ethoxide modified with acetylacetone (acac) as a Nb source favored the formation of dimeric and/or small oligomeric Nb centers on the surface of mesoporous silica while ammonium niobate(V) oxalate coupled with acac gave mostly site-isolated Nb species. The Nb-MMM-E materials catalyzed selectively oxidation of various unsaturated compounds of interest for fine and specialty chemistry using the green oxidant - aqueous hydrogen peroxide. Epoxidation of both electron rich and electron deficient C=C bonds could be accomplished over Nb-MMM-E. While catalysts with isolated Nb centers were preferable for the selective formation of epoxides sensitive to ring opening and overoxidation, both single site and oligomerized Nb centers were equally effective for the production of relatively stable epoxides. The truly heterogeneous nature of the catalysis over Nb-MMM-E and absence of Nb leaching into solution have been proved by hot filtration tests coupled with elemental analysis. The catalysts could be easily recovered by filtration and reused several times without significant deterioration of the catalytic performance.
KW - Alkene
KW - Epoxidation
KW - Evaporation-induced self-assembly
KW - Heterogeneous catalysis
KW - Hydrogen peroxide
KW - Mesoporous niobium-silicate
UR - http://www.scopus.com/inward/record.url?scp=84946092505&partnerID=8YFLogxK
U2 - 10.1016/j.jcat.2015.10.003
DO - 10.1016/j.jcat.2015.10.003
M3 - Article
AN - SCOPUS:84946092505
VL - 332
SP - 138
EP - 148
JO - Journal of Catalysis
JF - Journal of Catalysis
SN - 0021-9517
ER -
ID: 22554677