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Ziółek, Maria; Nowak, Izabela; Lavalley, Jean‐Claude

doi:10.1023/a:1019000619962

Cited by 88 publications

(21 citation statements)

References 25 publications

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“…In catalysis, niobium compounds can play various functions: promoters of active phase, supports, solid acids or redox materials [1,2]. Nb located in the walls of the mesoporous MCM-41 sieve generates Lewis acidity [3]. When NbMCM-41 mesoporous sieves are treated by ion-exchange with alkaline metals, one can expect the generation of basic sites on the material.…”

Section: Introductionmentioning

confidence: 99%

“…Our group has recently reported on the preparation of a new type of NbMCM-41 catalysts obtained by hydrothermal method [3] modified with alkali metals (M) towards basic catalyst applications [15,16]. It has been found that niobium located in the mesoporous material plays a role of structural promoter preventing the solid from the disordering caused by the treatment with alkali metal solution.…”

Section: Introductionmentioning

confidence: 99%

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Isomerization of Eugenol Under Ultrasound Activation Catalyzed by Alkali Modified Mesoporous NbMCM-41

et al. 2009

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The present paper discloses a new alternative method for the isomerization of eugenol to isoeugenol where mesoporous materials containing niobium are used as solid base catalysts, affording good yields of isomerized product and being environmentally friendly. Nb-containing MCM-41 mesoporous materials were modified with alkaline cations (Li, Na, K, Rb and Cs) and characterized by BET, FTIR, XRD, and UV-vis techniques. The prepared materials were tested in the isomerization of eugenol to isoeugenol by sonochemical and thermally-activated reactions. Li, Na, K, Rb, and Cs/NbMCM-41 catalysts are active catalyst for the preparation of isoeugenol, and selective to the trans-isomer. Rb/NbMCM-41 sample is the optimum catalysts for the reaction. This result is in accordance with the calculated basicity observed during the Knoevenagel probe reaction of basicity. Conversions around 90% are obtained when using Rb-NbMCM-41 catalysts, with 90% selectivity to trans-isoeugenol, under ultrasound activation. In contrast, conversion around 72% with 90% selectivity is attained under classical thermal activation. The catalysts were reused four times without a substantial decrease of activity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Isomerization of Eugenol Under Ultrasound Activation Catalyzed by Alkali Modified Mesoporous NbMCM-41

et al. 2009

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“…It is a reason for the high activity in the production of formaldehyde, shown by the pure matrices (NbMCM-41 and AlMCM-41). Both supports posses Lewis acid centre; NbMCM-41 in the form of framework Nb + species [19] and in AlMCM-41 extra framework aluminium species (table 2). The participation of Lewis acid sites in the methanol oxidation also explains why the various reducibility of iron species dependent on the nature of matrix as well as on the method of iron incorporation [16,20,21] do not influence the activity in methanol oxidation towards formaldehyde.…”

Section: Methanol Oxidationmentioning

confidence: 99%

Iron Modified MCM-41 Materials Characterised by Methanol Oxidation and Sulphurisation Reactions

2006

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SiMCM-41, AlMCM-41, NbMCM-41 were applied as supports for iron species introduced by wetness impregnation and chemical vapour deposition (CVD) methods. Methanol oxidation and sulphurisation were used for the characterisation of catalytic properties. The support nature as well as the type of iron species have no effect on the selectivity of methanol oxidation. However, they bear a significant influence on both the activity and selectivity in the reaction between methanol and hydrogen sulphide. The wetness impregnation of NbMCM-41 and AlMCM-41 with Fe salt leads to the most effective catalysts in the sulphurisation of methanol.

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“…Thanks to its hexagonal uniform one-dimensional mesopores ranging from 20 to 100 Å in diameter, its narrow pore size distribution and its high internal surface area, MCM-41 is a good catalyst for many reactions. However, pure Si-MCM-41 has limited catalytic activity that is why the incorporation of various metal has been tried to increase the acidity with the use of aluminium [3,4] and then to induce some redox properties notably with iron [5,6], vanadium [7,8], niobium [9,10] and copper [11,12] while keeping the framework intact. The metal cations are located in the skeleton or in the extraframework voids.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Gas Storage and Catalytic Gas Production Using Zeolites—A New Concept for Extending Lifetime Gas Delivery

et al. 2008

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Copper containing MCM-41 materials can be used to both store gaseous nitric oxide and to catalytically produce nitric oxide from nitrite. The active species for the reaction is copper (I). Addition of cysteine to the solution in contact with the material has different effects depending on how much Cu(I) is present. This is a new method of extending the lifetime of gas delivery from a gas storage material.

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Cited by 88 publications

References 25 publications

Isomerization of Eugenol Under Ultrasound Activation Catalyzed by Alkali Modified Mesoporous NbMCM-41

Isomerization of Eugenol Under Ultrasound Activation Catalyzed by Alkali Modified Mesoporous NbMCM-41

Iron Modified MCM-41 Materials Characterised by Methanol Oxidation and Sulphurisation Reactions

Simultaneous Gas Storage and Catalytic Gas Production Using Zeolites—A New Concept for Extending Lifetime Gas Delivery

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