TY - JOUR

T1 - Tungsten-based mesoporous silicates W-MMM-E as heterogeneous catalysts for liquid-phase oxidations with aqueous H2O2

AU - Maksimchuk, Nataliya

AU - Ivanchikova, Irina

AU - Zalomaeva, Olga

AU - Chesalov, Yurii

AU - Shmakov, Alexandr

AU - Zaikovskii, Vladimir

AU - Kholdeeva, Oxana

PY - 2018/3/1

Y1 - 2018/3/1

N2 - Mesoporous tungsten-silicates, W-MMM-E, have been prepared following evaporation-induced self-assembly methodology and characterized by elemental analysis, XRD, N2 adsorption, STEM-HAADF (high angle annular dark field in scanning-TEM mode), DRS UV-vis, and Raman techniques. DRS UV-vis showed the presence of two types of tungsten oxo-species in W-MMM-E samples: isolated tetrahedrally and oligomeric octahedrally coordinated ones, with the ratio depending on the content of tungsten in the catalyst. Materials with lower W loading have a higher contribution from isolated species, regardless of the preparation method. W-MMM-E catalyzes selectively oxidize of a range of alkenes and organic sulfides, including bulky terpene or thianthrene molecules, using green aqueous H2O2. The selectivity of corresponding epoxides reached 85–99% in up to 80% alkene conversions, while sulfoxides formed with 84–90% selectivity in almost complete sulfide conversions and a 90–100% H2O2 utilization efficiency. The true heterogeneity of catalysis over W-MMM-E was proved by hot filtration tests. Leaching of inactive W species depended on the reaction conditions and initial W loading in the catalyst. After optimization of the catalyst system, it did not exceed 20 ppm and 3 ppm for epoxidation and sulfoxidation reactions, respectively. Elaborated catalysts could be easily retrieved by filtration and reused several times with maintenance of the catalytic behavior.

AB - Mesoporous tungsten-silicates, W-MMM-E, have been prepared following evaporation-induced self-assembly methodology and characterized by elemental analysis, XRD, N2 adsorption, STEM-HAADF (high angle annular dark field in scanning-TEM mode), DRS UV-vis, and Raman techniques. DRS UV-vis showed the presence of two types of tungsten oxo-species in W-MMM-E samples: isolated tetrahedrally and oligomeric octahedrally coordinated ones, with the ratio depending on the content of tungsten in the catalyst. Materials with lower W loading have a higher contribution from isolated species, regardless of the preparation method. W-MMM-E catalyzes selectively oxidize of a range of alkenes and organic sulfides, including bulky terpene or thianthrene molecules, using green aqueous H2O2. The selectivity of corresponding epoxides reached 85–99% in up to 80% alkene conversions, while sulfoxides formed with 84–90% selectivity in almost complete sulfide conversions and a 90–100% H2O2 utilization efficiency. The true heterogeneity of catalysis over W-MMM-E was proved by hot filtration tests. Leaching of inactive W species depended on the reaction conditions and initial W loading in the catalyst. After optimization of the catalyst system, it did not exceed 20 ppm and 3 ppm for epoxidation and sulfoxidation reactions, respectively. Elaborated catalysts could be easily retrieved by filtration and reused several times with maintenance of the catalytic behavior.

KW - Alkene

KW - Epoxidation

KW - Evaporation-induced self-assembly

KW - Heterogeneous catalysis

KW - Hydrogen peroxide

KW - Mesoporous tungsten-silicate

KW - SELECTIVE OXIDATION

KW - heterogeneous catalysis

KW - hydrogen peroxide

KW - COMPLEXES

KW - evaporation-induced self-assembly

KW - OXIDE CATALYSTS

KW - EPOXIDATION

KW - epoxidation

KW - alkene

KW - OLEFINS

KW - mesoporous tungsten-silicate

KW - HYDROGEN-PEROXIDE

KW - EFFICIENT

KW - NIOBIUM-SILICATES

KW - METATHESIS

KW - GREEN APPROACH

UR - http://www.scopus.com/inward/record.url?scp=85042694558&partnerID=8YFLogxK

U2 - 10.3390/catal8030095

DO - 10.3390/catal8030095

M3 - Article

AN - SCOPUS:85042694558

VL - 8

JO - Catalysts

JF - Catalysts

SN - 2073-4344

IS - 3

M1 - 95

ER -