Magnetic nanoparticle supported polyoxometalate: An efficient and reusable catalyst for solvent-free synthesis of α-aminophosphonates

Hamadi, Hosein; Kooti, M.; Afshari, Mozhgan; Ghiasifar, Z.; Adibpour, Neda

doi:10.1016/j.molcata.2013.02.018

Cited by 54 publications

(27 citation statements)

References 34 publications

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“…According to reference pattern in Figure a, the broad diffraction peaks appearing in Figure b‐d at 2θ = 25.2° (101), 37.9° (103) and 48.3° (200) just could be related to deformed anatase structure and the reason for peak broadening is conceivably due to the HPW, cobalt oxide, and manganese oxide in the TiO 2 matrix which prevented formation a uniform anatase crystalline TiO 2 . No diffraction peaks could be assigned to HPW, cobalt oxide, and manganese oxide which means that these components form too small crystallites or are well dispersed in the mesoporous anatase TiO 2 framework rather than existing as aggregates in the matrix . In authorization of this comment, results obtained from EDX and elemental mapping analysis (Figure d inset) indicate high dispersion of HPW and other components over the TiO 2 network, which could explain why XRD of the catalysts did not show any crystalline phases related to the phosphotungstic acid and others …”

Section: Resultsmentioning

confidence: 95%

Selective vapor‐phase oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H₃PW₁₂O₄₀@TiO₂ using molecular oxygen as a green oxidant

Masoomi

Ghiaci

Rego³

2018

Applied Organom Chemis

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The oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H3PW12O40@TiO2 was investigated. The experimental results demonstrated that the prepared catalyst effectively catalyzed the oxidation of o‐xylene to phthalic anhydride. Also, the synergistic effect between three metals plays vital roles in this reaction. From a green chemistry point of view, this method is environmentally friendly due to carrying out the oxidation in a fixed‐bed reactor under solvent‐free condition and using molecular oxygen as a green and cheap oxidizing agent. The resulting solid catalysts were characterized by FT‐IR, XRD, XPS, ICP‐OES, FESEM, TEM, EDX, DR‐UV spectroscopy, BET and thermogravimetric analysis. The oxidation of o‐xylene yields four products: o‐tolualdehyde, phthaldialdehyde, phthalide and finally phthalic anhydride as the main product. The reaction conditions for oxidation of o‐xylene were optimized by varying the temperature, weight hourly space velocity and oxygen flow rate (contact time). The optimum weight percentage of phosphotungstic acid (HPW) and Co/Mn for phthalic anhydride production were 15 wt % and 2 wt%, respectively. The best Co/Mn ratio was found to be 10/1. Oxygen flow rate was very important on the phthalic anhydride formation. The optimum conditions for oxidation of o‐xylene were T = 370 °C, WHSV = 0.5 h−1 and oxygen flow rate = 10 mL min−1. Under optimized conditions, a maximum of 88.2% conversion and 75.5% selectivity to phthalic anhydride was achieved with the fresh catalyst. Moreover, reusability of the catalyst was studied and catalytic activity remained unchanged after at least five cycles.

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Section: Resultsmentioning

confidence: 95%

Selective vapor‐phase oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H₃PW₁₂O₄₀@TiO₂ using molecular oxygen as a green oxidant

Masoomi

Ghiaci

Rego³

2018

Applied Organom Chemis

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“…In spite of POMs advantages, their high solubility limits their applications . So, the development of highly efficient, easily recoverable and reusable heterogeneous POM catalyst is essential.…”

Section: Poms and Their Composites As Photocatalystmentioning

confidence: 99%

Polyoxometalates and Their Composites as Photocatalysts for Organic Pollutants Degradation in Aqueous Media—A Review

Dehghani

Aber

Mahdizadeh

2018

CLEAN Soil Air Water

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Polyoxometalates (POMs), eco‐friendly solid acids, are polyatomic anions containing transition metal (group 5 or group 6) oxyanions linked together through shared oxygen atoms. First, the structure, classification, synthesis, non‐photocatalytic applications, and their photocatalytic properties and applications are presented. POMs are very interesting due to their unique and remarkable characteristics. One of the most attractive characteristics of POMs is their activity as an electron relay, that is, they can undergo stepwise multi‐electron redox reactions while their construction remains intact. Based on this characteristic, POMs have been widely used as photooxidation catalysts for organic and inorganic contaminants removal. According to the literature, POMs are useful homogeneous photocatalysts for the mineralization of dyes, phenol and its derivatives, chloroacetic acids, and pesticides and wood pulp bleaching. Applications of POMs have been limited because of their high solubility in water. Immobilization and solidification of POMs using different methods and various supports for making them reusable are studied in this review. Varieties of composites of POMs are synthesized to make them photorespond to the visible light region.

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“…A magnetic nanoparticle-supported polyoxometalate was reported by Kooti et al [61]. The supported phosphotungstic acid was indicated to be an effective heterogeneous catalyst for the preparation of α-aminophosphonates under solvent-free conditions at ambient temperature.…”

Section: Ionic Liquids Immobilized On Magnetic Nanoparticlesmentioning

confidence: 99%

Recent advances in catalysts immobilized on magnetic nanoparticles

Mokhtary

2016

J IRAN CHEM SOC

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2]. Furthermore, enhancing the percentages of exposed highly reactive facets, at nanoscale, does improve the efficiency of materials in various applications such as photocatalysis and dye-sensitized solar cells [3]. By presenting individual properties, nanoparticles can become a kind of structure unit, in other words, "artificial atoms" to conduct a new type of materials which have difficult in estimating collective properties [4]. Through green nanotechnology, we can get contrivable nanomaterial that contains unique characters which bulk materials never have [5]. This means that we are creating materials with good catalytic activity, stability and more selectivity via changing their forms, sizes and morphologies [6]. Applications of nanoparticles in catalytic reactions are because as size decreases, the surface area-to-volume ratio increases, which enhanced interaction between the reactant and the catalyst, which are needed for high catalytic efficiencies [7]. Unsupported nanoparticles are often less stable, and usually coagulation is inevitable during the catalytic reactions [8]. To generate stable nanoparticles with good activity, stabilizing the surface is required. Protection has been performed by the addition of polymers or longchain alkyl surfactants with polar functional groups that attached to the nanoparticle surface via covalent or electrostatic interactions [9, 10]. Alternatively, nanoparticles have been immobilized or grafted onto inorganic supports to improve their stabilization and recycling ability [12]. Progress in the discovery of new support materials for the heterogenization of homogeneous catalysts has been periodically reviewed [13]. In this article, the green catalytic processes and recent advances in organic transformations catalyzed by magnetically retrievable catalysts (MRCs) are highlighted. Prior to this, methods for the synthesis of catalysts immobilized on magnetic nanoparticles will be addressed briefly.Abstract Unsupported nanoparticles are often less stable, and usually coagulation is unavoidable during the catalytic reactions. To generate stable nanoparticles with good activity, stabilizing the surface is required. Protection has been performed by the addition of polymers or long-chain alkyl surfactants with polar functional groups that attached to the nanoparticle surface via covalent or electrostatic interactions. Alternatively, nanoparticles have been immobilized or grafted onto inorganic supports to improve their stabilization and recycling ability. In this article, the green catalytic processes and recent advances in organic transformations catalyzed by magnetically retrievable catalysts are reviewed. Prior to this, methods for the synthesis of catalysts immobilized on magnetic nanoparticles are addressed briefly.

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Magnetic nanoparticle supported polyoxometalate: An efficient and reusable catalyst for solvent-free synthesis of α-aminophosphonates

Cited by 54 publications

References 34 publications

Selective vapor‐phase oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H₃PW₁₂O₄₀@TiO₂ using molecular oxygen as a green oxidant

Selective vapor‐phase oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H₃PW₁₂O₄₀@TiO₂ using molecular oxygen as a green oxidant

Polyoxometalates and Their Composites as Photocatalysts for Organic Pollutants Degradation in Aqueous Media—A Review

Recent advances in catalysts immobilized on magnetic nanoparticles

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Magnetic nanoparticle supported polyoxometalate: An efficient and reusable catalyst for solvent-free synthesis of α-aminophosphonates

Cited by 54 publications

References 34 publications

Selective vapor‐phase oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H3PW12O40@TiO2 using molecular oxygen as a green oxidant

Selective vapor‐phase oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H3PW12O40@TiO2 using molecular oxygen as a green oxidant

Polyoxometalates and Their Composites as Photocatalysts for Organic Pollutants Degradation in Aqueous Media—A Review

Recent advances in catalysts immobilized on magnetic nanoparticles

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Product

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About

Selective vapor‐phase oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H₃PW₁₂O₄₀@TiO₂ using molecular oxygen as a green oxidant

Selective vapor‐phase oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H₃PW₁₂O₄₀@TiO₂ using molecular oxygen as a green oxidant