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Hidalgo G, Devillers M, Gaigneaux EM. Hybrid Materials Based on Keggin Phosphotungstate and Bipyridine with Valuable Hydrophobic and Redox Properties. Inorg Chem 2022; 61:12494-12507. [PMID: 35925672 DOI: 10.1021/acs.inorgchem.2c00342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A thorough investigation of two novel hybrid materials, namely, (2,2'-Hbpy)3[PW12O40] and (4,4'-H2bpy)1.5[PW12O40]·1.5H2O built from Keggin phosphotungstic acid (PTA) and bipyridine, describes the impact of bipyridine isomers in their formation and physicochemical properties. The hybrids' formation was confirmed by powder X-ray diffraction, while infrared spectroscopy (IR) proved the polyoxometalate (POM) structural preservation. The stoichiometric composition and thermal stability of the hybrids were solved by thermogravimetric analysis-mass spectrometry, which also revealed newly acquired hydrophobic properties. Raman and IR spectroscopies demonstrated that the POM skeleton units in both hybrids were distorted compared to the POM in PTA, which induced a decrease of their reduction potentials as observed by diffuse reflectance ultraviolet-visible spectroscopy (DR-UV-vis). The hybrids' acidity was assessed by ammonia temperature-programmed desorption, which showed no remaining acid sites compared to the strong acidic character of the pristine PTA. The properties of the hybrids were tested in the epoxidation of cyclooctene in the presence of H2O2. The reaction was boosted when the hybrids were pre-activated with H2O2.
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Affiliation(s)
- Gabriel Hidalgo
- Institute of Condensed Matter and Nanosciences (IMCN), Université Catholique de Louvain, Place Louis Pasteur, 1, P.O. Box L4.01.09, 1348 Louvain-la-Neuve, Belgium
| | - Michel Devillers
- Institute of Condensed Matter and Nanosciences (IMCN), Université Catholique de Louvain, Place Louis Pasteur, 1, P.O. Box L4.01.09, 1348 Louvain-la-Neuve, Belgium
| | - Eric M Gaigneaux
- Institute of Condensed Matter and Nanosciences (IMCN), Université Catholique de Louvain, Place Louis Pasteur, 1, P.O. Box L4.01.09, 1348 Louvain-la-Neuve, Belgium
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2
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Active epoxidation bipyridine-oxodiperoxotungstate catalysts. MOLECULAR CATALYSIS 2022. [DOI: 10.1016/j.mcat.2022.112479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Immobilization of Polyoxometalates on Carbon Nanotubes: Tuning Catalyst Activity, Selectivity and Stability in H2O2-Based Oxidations. Catalysts 2022. [DOI: 10.3390/catal12050472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In recent years, carbon nanotubes (CNTs), including N-doped ones (N-CNTs), have received significant attention as supports for the construction of heterogeneous catalysts. In this work, we summarize our progress in the application of (N)-CNTs for immobilization of anionic metal-oxygen clusters or polyoxometalates (POMs) and use of (N)-CNTs-supported POM as catalysts for liquid-phase selective oxidation of organic compounds with the green oxidant–aqueous hydrogen peroxide. We discuss here the main factors, which favor adsorption of POMs on (N)-CNTs and ensure a quasi-molecular dispersion of POM on the surface and their strong attachment to the support. The effects of the POM nature, N-doping of CNTs, acid additives, and other factors on the POM immobilization process and catalytic activity/selectivity of the (N)-CNTs-immobilized POMs are analyzed. Particular attention is drawn to the critical issue of the catalyst stability and reusability. The scope and limitations of the POM/(N)-CNTs catalysts in H2O2-based selective oxidations are discussed.
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Mesoporous Methyl-Functionalized Titanosilicate Produced by Aerosol Process for the Catalytic Epoxidation of Olefins. Catalysts 2021. [DOI: 10.3390/catal11020196] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Titanosilicates (Ti-SiO2) are well-known catalysts for the epoxidation of olefins. Isolated Ti inserted in the silica framework in tetrahedral coordination are the active species. Recently, adjusting the hydrophobic/hydrophilic balance of such catalysts’ surfaces has appeared as a promising tool to further boost their performance. However, adjusting the hydrophobic/hydrophilic balance via a one-pot classical sol-gel generally leads to a decrease in the Ti dispersion and/or collapse of the pore network. To overcome this limitation, hydrophobic mesoporous Ti-SiO2 were here synthesized by aerosol-assisted one-pot sol–gel, which allowed the simultaneous control of their Ti loading, degree of methyl-functionalization, and textural properties. Methyl-functionalization was achieved by a partial substitution of tetraethoxy silane (TEOS) by methyltriethoxy silane (MTES) in different ratios. Solid-state 29Si-NMR, FTIR, TGA, and vapor-phase water adsorption showed that methyl moieties were effectively incorporated, conferring a hydrophobic property to the Ti-SiO2 catalysts. ICP-AES, DRUV, XPS, and N2 physisorption demonstrated that Ti dispersion and textural properties were both successfully preserved upon the incorporation of the methyl moieties. In the epoxidation of cyclooctene with tert-butyl hydroperoxide as oxidant, the hydrophobic Ti-SiO2 showed higher catalytic performance than pristine Ti-SiO2 prepared without MTES. In addition to disentangling the positive effect of adjusting the hydrophobic/hydrophilic balance of epoxidation catalysts on their performance, this contribution highlights the advantages of the aerosol procedure to synthesize mesoporous functionalized catalysts with very high dispersion of active sites.
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Masteri-Farahani M, Alavijeh MK, Hosseini MS. Venturello anion immobilized on the surface of porous activated carbon as heterogeneous catalyst for the epoxidation of olefins. REACTION KINETICS MECHANISMS AND CATALYSIS 2020. [DOI: 10.1007/s11144-020-01764-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Hosseinyzade SS, Zonoz FM, Bahramian B. Synthesis, characterization, and application of a new nanohybrid Schiff base polyoxometalate in epoxidation of olefins in the presence of tert-butyl hydroperoxide. J COORD CHEM 2020. [DOI: 10.1080/00958972.2020.1727453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | | | - Bahram Bahramian
- College of Chemistry, Shahrood University of Technology, Shahrood, Iran
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Evtushok VY, Ivanchikova ID, Podyacheva OY, Stonkus OA, Suboch AN, Chesalov YA, Zalomaeva OV, Kholdeeva OA. Carbon Nanotubes Modified by Venturello Complex as Highly Efficient Catalysts for Alkene and Thioethers Oxidation With Hydrogen Peroxide. Front Chem 2019; 7:858. [PMID: 31921779 PMCID: PMC6923790 DOI: 10.3389/fchem.2019.00858] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 11/26/2019] [Indexed: 12/02/2022] Open
Abstract
In this work, we elaborated heterogeneous catalysts on the basis of the Venturello complex [PO4{WO(O2)2}4]3- (PW4) and nitrogen-free or nitrogen-doped carbon nanotubes (CNTs or N-CNTs) for epoxidation of alkenes and sulfoxidation of thioethers with aqueous hydrogen peroxide. Catalysts PW4/CNTs and PW4/N-CNTs (1.8 at. % N) containing 5-15 wt. % of PW4 and differing in acidity have been prepared and characterized by elemental analysis, N2 adsorption, IR spectroscopy, HR-TEM, and HAADF-STEM. Studies by STEM in HAADF mode revealed a quasi-molecular dispersion of PW4 on the surface of CNTs. The addition of acid during the immobilization is not obligatory to ensure site isolation and strong binding of PW4 on the surface of CNTs, but it allows one to increase the PW4 loading and affects both catalytic activity and product selectivity. Catalytic performance of the supported PW4 catalysts was evaluated in H2O2-based oxidation of two model substrates, cyclooctene and methyl phenyl sulfide, under mild conditions (25-50°C). The best results in terms of activity and selectivity were obtained using PW4 immobilized on N-free CNTs in acetonitrile or dimethyl carbonate as solvents. Catalysts PW4/CNTs can be applied for selective oxidation of a wide range of alkenes and thioethers provided a balance between activity and selectivity of the catalyst is tuned by a careful control of the amount of acid added during the immobilization of PW4. Selectivity, conversion, and turnover frequencies achieved in epoxidations over PW4/CNTs catalysts are close to those reported in the literature for homogeneous systems based on PW4. IR spectroscopy confirmed the retention of the Venturello structure after use in the catalytic reactions. The elaborated catalysts are stable to metal leaching, show a truly heterogeneous nature of the catalysis, can be easily recovered by filtration, regenerated by washing and evacuation, and then reused several times without loss of the catalytic performance.
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Affiliation(s)
- Vasiliy Yu Evtushok
- Department of Fine Organic Synthesis and Renewable Energy Sources, Boreskov Institute of Catalysis, Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia
| | - Irina D. Ivanchikova
- Department of Fine Organic Synthesis and Renewable Energy Sources, Boreskov Institute of Catalysis, Novosibirsk, Russia
| | - Olga Yu Podyacheva
- Department of Fine Organic Synthesis and Renewable Energy Sources, Boreskov Institute of Catalysis, Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia
| | - Olga A. Stonkus
- Department of Fine Organic Synthesis and Renewable Energy Sources, Boreskov Institute of Catalysis, Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia
| | - Arina N. Suboch
- Department of Fine Organic Synthesis and Renewable Energy Sources, Boreskov Institute of Catalysis, Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia
| | - Yuri A. Chesalov
- Department of Fine Organic Synthesis and Renewable Energy Sources, Boreskov Institute of Catalysis, Novosibirsk, Russia
| | - Olga V. Zalomaeva
- Department of Fine Organic Synthesis and Renewable Energy Sources, Boreskov Institute of Catalysis, Novosibirsk, Russia
| | - Oxana A. Kholdeeva
- Department of Fine Organic Synthesis and Renewable Energy Sources, Boreskov Institute of Catalysis, Novosibirsk, Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia
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Rayati S, Pournaser N, Nejabat F, Nafarieh P. Aerobic oxidation of cyclohexene over Mn-porphyrin based nanocatalyst: Supported vs unsupported catalyst. INORG CHEM COMMUN 2019. [DOI: 10.1016/j.inoche.2019.107447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Kasinathan P, Lang C, Radhakrishnan S, Schnee J, D'Haese C, Breynaert E, Martens JA, Gaigneaux EM, Jonas AM, Fernandes AE. “Click” Silica‐Supported Sulfonic Acid Catalysts with Variable Acid Strength and Surface Polarity. Chemistry 2019; 25:6753-6762. [DOI: 10.1002/chem.201806186] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Indexed: 01/02/2023]
Affiliation(s)
- Palraj Kasinathan
- Institute of Condensed Matter and NanosciencesUCLouvain 1348 Louvain-la-Neuve Belgium
| | - Charlotte Lang
- Institute of Condensed Matter and NanosciencesUCLouvain 1348 Louvain-la-Neuve Belgium
| | - Sambhu Radhakrishnan
- Center for Surface Chemistry and Catalysis, Characterization and Application TeamKULeuven 3001 Leuven Belgium
| | - Josefine Schnee
- Institute of Condensed Matter and NanosciencesUCLouvain 1348 Louvain-la-Neuve Belgium
| | - Cécile D'Haese
- Institute of Condensed Matter and NanosciencesUCLouvain 1348 Louvain-la-Neuve Belgium
| | - Eric Breynaert
- Center for Surface Chemistry and Catalysis, Characterization and Application TeamKULeuven 3001 Leuven Belgium
| | - Johan A. Martens
- Center for Surface Chemistry and Catalysis, Characterization and Application TeamKULeuven 3001 Leuven Belgium
| | - Eric M. Gaigneaux
- Institute of Condensed Matter and NanosciencesUCLouvain 1348 Louvain-la-Neuve Belgium
| | - Alain M. Jonas
- Institute of Condensed Matter and NanosciencesUCLouvain 1348 Louvain-la-Neuve Belgium
| | - Antony E. Fernandes
- Institute of Condensed Matter and NanosciencesUCLouvain 1348 Louvain-la-Neuve Belgium
- Current address: Certech Rue Jules Bordet 7180 Seneffe Belgium
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Mesoporous SiO2-TiO2 epoxidation catalysts: Tuning surface polarity to improve performance in the presence of water. MOLECULAR CATALYSIS 2018. [DOI: 10.1016/j.mcat.2018.04.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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11
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Zerrouki M, Boudjema S, Choukchou-Braham A, Rekkab-Hammoumraoui I. Synthesis, characterization and optimization of heterogeneous catalytic cyclohexene oxidation by tungstophospho(aqua)ruthenate via the fractional factorial design methodology. NEW J CHEM 2018. [DOI: 10.1039/c8nj02690d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Keggin-type tungstophospho(aqua)ruthenate (PRuW) was synthesized and supported on acid activated montmorillonite under mild conditions.
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Affiliation(s)
- Mostapha Zerrouki
- Laboratoire de Catalyse et Synthèse en Chimie Organique
- Faculté des Sciences
- Université de Tlemcen
- Algeria
| | - Souheyla Boudjema
- Laboratoire de Catalyse et Synthèse en Chimie Organique
- Faculté des Sciences
- Université de Tlemcen
- Algeria
- Département de Forage et Mécanique des Chantiers Pétroliers
| | | | - Ilhem Rekkab-Hammoumraoui
- Laboratoire de Catalyse et Synthèse en Chimie Organique
- Faculté des Sciences
- Université de Tlemcen
- Algeria
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12
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Masteri‐Farahani M, Modarres M. Heterogenized peroxopolyoxotungstate catalyst on the surface of clicked magnetite‐graphene oxide nanocomposite: Magnetically recoverable epoxidation catalyst. Appl Organomet Chem 2017. [DOI: 10.1002/aoc.4142] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
| | - M. Modarres
- Faculty of ChemistryKharazmi University Tehran Islamic Republic of Iran
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13
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Masteri-Farahani M, Modarres M. New Hybrid Nanomaterials Derived from Chemical Functionalization of Clicked Graphene Oxide / Magnetite Nanocomposite with Peroxopolyoxotungstate Species. ChemistrySelect 2017. [DOI: 10.1002/slct.201701690] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
| | - Maryam Modarres
- Faculty of Chemistry; Kharazmi University; Tehran, Islamic Republic of Iran
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14
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Raj G, Swalus C, Delcroix M, Devillers M, Dupont-Gillain C, Gaigneaux EM. In situ quartz crystal microbalance monitoring of the adsorption of polyoxometalate on a polyampholyte polymer matrix. J Colloid Interface Sci 2015; 445:24-30. [DOI: 10.1016/j.jcis.2014.12.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 12/08/2014] [Accepted: 12/12/2014] [Indexed: 10/24/2022]
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15
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Goovaerts V, Stroobants K, Absillis G, Parac-Vogt TN. Eu(III) luminescence and tryptophan fluorescence spectroscopy as a tool for understanding interactions between hen egg white lysozyme and metal-substituted Keggin type polyoxometalates. J Inorg Biochem 2015; 150:72-80. [PMID: 25870147 DOI: 10.1016/j.jinorgbio.2015.03.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 03/17/2015] [Accepted: 03/26/2015] [Indexed: 01/11/2023]
Abstract
The interaction between the lacunary Keggin K7PW11O39, the Eu(III)-substituted Keggin K4EuPW11O39 (Eu-Keggin) and the Ce(IV)-substituted Keggin [Me2NH2]10[Ce(PW11O39)2] (Ce-Keggin) polyoxometalates (POMs), and the proteins hen egg white lysozyme (HEWL) and the structurally homologous α-lactalbumin (α-LA) was studied by steady state and time-resolved Eu(III) luminescence and tryptophan (Trp) fluorescence spectroscopy. The excitation spectrum of Eu-Keggin at lower concentrations ([Eu-Keggin]<100 μM) is dominated by a ligand-to-metal charge transfer band (291 nm). For higher concentrations ([Eu-Keggin]>250 μM) the (5)L6←(7)F0 transition becomes the most intense peak. In the absence of protein, the number of coordinated water molecules to the Eu(III) centre of Eu-Keggin is 4, indicating a 1:1 Eu(III):POM species. In the presence of phosphate buffer this number linearly decreases from 4 to 2 upon increasing phosphate buffer concentration. Upon addition of HEWL, there are no coordinated water molecules, suggesting interaction between Eu-Keggin and the protein surface. In addition, this interaction results in a more than threefold increase of the hypersensitive (5)D0→(7)F2 transition for the Eu-Keggin/HEWL mixture. The calculated association constant amounted to 2.2×10(2) M(-1) for the Eu-Keggin/HEWL complex. Tryptophan fluorescence quenching studies were performed and the quenching constants were calculated to be 9.1×10(4) M(-1), 4×10(4) M(-1) and 4.1×10(5) M(-1) for the lacunary Keggin/HEWL, the Eu-Keggin/HEWL and the Ce-Keggin/HEWL complexes, respectively. The number of bound POM molecules to HEWL was 1.04 for the lacunary Keggin POM, and 1.0 for Eu-Keggin, indicating the formation of a 1:1 POM/HEWL complex. The value of 1.38 for Ce-Keggin might indicate a transition from 1:1 to 1:2 interaction.
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Affiliation(s)
- Vincent Goovaerts
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
| | - Karen Stroobants
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
| | - Gregory Absillis
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
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Nojima S, Kamata K, Suzuki K, Yamaguchi K, Mizuno N. Selective Oxidation with Aqueous Hydrogen Peroxide by [PO4{WO(O2)2}4]3−Supported on Zinc-Modified Tin Dioxide. ChemCatChem 2015. [DOI: 10.1002/cctc.201402975] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Boudjema S, Vispe E, Choukchou-Braham A, Mayoral JA, Bachir R, Fraile JM. Preparation and characterization of activated montmorillonite clay supported 11-molybdo-vanado-phosphoric acid for cyclohexene oxidation. RSC Adv 2015. [DOI: 10.1039/c4ra13604g] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Heterogenization of homogenous catalysts consisting of vanadium substituted polyphosphomolybdate with Keggin structure supported on activated bentonite for epoxidation of cyclohexene.
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Affiliation(s)
- S. Boudjema
- Laboratoire de Catalyse et Synthèse en Chimie Organique
- Faculté des Sciences
- Université de Tlemcen
- Algeria
| | - E. Vispe
- Departamento de Química Orgánica
- Instituto de Síntesis Química y Catálisis Homogénea
- Facultad de Ciencias
- Universidad de Zaragoza-CSIC
- E-50009 Zaragoza
| | - A. Choukchou-Braham
- Laboratoire de Catalyse et Synthèse en Chimie Organique
- Faculté des Sciences
- Université de Tlemcen
- Algeria
| | - J. A. Mayoral
- Departamento de Química Orgánica
- Instituto de Síntesis Química y Catálisis Homogénea
- Facultad de Ciencias
- Universidad de Zaragoza-CSIC
- E-50009 Zaragoza
| | - R. Bachir
- Laboratoire de Catalyse et Synthèse en Chimie Organique
- Faculté des Sciences
- Université de Tlemcen
- Algeria
| | - J. M. Fraile
- Departamento de Química Orgánica
- Instituto de Síntesis Química y Catálisis Homogénea
- Facultad de Ciencias
- Universidad de Zaragoza-CSIC
- E-50009 Zaragoza
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Raj G, Swalus C, Arendt E, Eloy P, Devillers M, Gaigneaux EM. Controlling the dispersion of supported polyoxometalate heterogeneous catalysts: impact of hybridization and the role of hydrophilicity-hydrophobicity balance and supramolecularity. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2014; 5:1749-59. [PMID: 25383286 PMCID: PMC4222433 DOI: 10.3762/bjnano.5.185] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 09/19/2014] [Indexed: 06/04/2023]
Abstract
The hybridization of polyoxometalates (POMs) through an organic-inorganic association offers several processing advantages in the design of heterogeneous catalysts. A clear understanding of the organization of these hybrid materials on solid surfaces is necessary to optimise their properties. Herein, we report for the first time the organization of Keggin phosphotungstic [PW12O40](3-) and Wells-Dawson (WD) phosphomolybdic [P2Mo18O62](6-) anions deposited on mica (hydrophilic), and highly oriented pyrolytic graphite (HOPG) (hydrophobic) surfaces. Next, the supramolecular organization of the organic-inorganic hybrid materials formed from the association of POM anions and dimethyldioctadecylammonium bromide (DODA) is investigated as a function of the hydrophilic or hydrophobic nature of the surfaces. The height of the Keggin-POM anions, measured with tapping mode (TM-AFM) is always in good agreement with the molecular dimension of symmetric Keggin-POM anions (ca. 1 nm). However, the asymmetric WD-POM anions form monolayer assemblies on the surfaces with the orientation of their long molecular axis (ca. 1.6 nm) depending on the hydrophilic or hydrophobic properties of the substrate. Namely, the long axis is parallel on mica, and perpendicular on HOPG. When hybridized with DODA, the organization of the hybrid material is dictated by the interaction of the alkyl side chains of DODA with the substrate surface. On HOPG, the DODA-POM hybrid forms small domains of epitaxially arranged straight nanorod structures with their orientation parallel to each other. Conversely, randomly distributed nanospheres are formed when the hybrid material is deposited on freshly cleaved mica. Finally, a UV-ozone treatment of the hybrid material allows one to obtain highly dispersed isolated POM entities on both hydrophilic and hydrophobic surfaces. The hybridization strategy to prevent the clustering of POMs on various supports would enable to develop highly dispersed POM-based heterogeneous catalysts with enhanced functionalities.
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Affiliation(s)
- Gijo Raj
- Institute of Condensed Matter and Nanosciences, Division MOlecules, Solids and reactiviTy, Université catholique de Louvain, Croix du Sud 2, L7.05.17, B-1348, Louvain-la-Neuve, Belgium
- CEA Grenoble, INAC, UMR 5819 SPRAM (CEA/CNRS/UJF-Grenoble 1), Laboratoire d’Electronique Moléculaire, Organique et Hybride, 17 rue des Martyrs, 38054 Grenoble cedex 9, France
| | - Colas Swalus
- Institute of Condensed Matter and Nanosciences, Division MOlecules, Solids and reactiviTy, Université catholique de Louvain, Croix du Sud 2, L7.05.17, B-1348, Louvain-la-Neuve, Belgium
| | - Eglantine Arendt
- Institute of Condensed Matter and Nanosciences, Division MOlecules, Solids and reactiviTy, Université catholique de Louvain, Croix du Sud 2, L7.05.17, B-1348, Louvain-la-Neuve, Belgium
| | - Pierre Eloy
- Institute of Condensed Matter and Nanosciences, Division MOlecules, Solids and reactiviTy, Université catholique de Louvain, Croix du Sud 2, L7.05.17, B-1348, Louvain-la-Neuve, Belgium
| | - Michel Devillers
- Institute of Condensed Matter and Nanosciences, Division MOlecules, Solids and reactiviTy, Université catholique de Louvain, Croix du Sud 2, L7.05.17, B-1348, Louvain-la-Neuve, Belgium
| | - Eric M Gaigneaux
- Institute of Condensed Matter and Nanosciences, Division MOlecules, Solids and reactiviTy, Université catholique de Louvain, Croix du Sud 2, L7.05.17, B-1348, Louvain-la-Neuve, Belgium
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