Journal of Molecular Catalysis A: Chemical 2006, 253, 123-131

Từ Thư viện Khoa học VLOS
Bước tới: chuyển hướng, tìm kiếm
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Highly accessible catalytic sites on recyclable organosilane-functionalized magnetic nanoparticles: An alternative to functionalized porous silica catalysts
 Tạp chí Journal of Molecular Catalysis A: Chemical 2006 ; 253 ():123-131
 Tác giả   Nam T. S. Phan, and Christopher W. Jones
 Nơi thực hiện   School of Chemical & Biomolecular Engineering

Georgia Institute of Technology, Atlanta, GA 30332, USA

 Từ khóa   Knoevenagel condensation; Nanoparticle; Magnetic separation; Base catalyst
  DOI   URL  [ PDF]


English

Abstract

Diaminosilane-functionalized cobalt spinel ferrite (CoFe2O4) magnetic nanoparticles are synthesized and used as efficient heterogeneous base catalysts for the Knoevenagel condensation of aromatic and heteroaromatic aldehydes with malononitrile. The magnetic nanoparticle catalyst is characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and nitrogen physisorption measurements. Quantitative conversion of the reactants is achieved under mild conditions. Recovery of the catalyst is easily achieved by magnetic decantation. The supported catalyst is reused five times without significant degradation in catalytic activity. No contribution from homogeneous catalysis due to active amine species leaching into reaction solution is detected. The performance of the magnetic base catalyst in the Knoevenagel reaction is directly compared with diamine-functionalized SBA-15 and MCM-48. Reaction rates over the non-porous, magnetic nanoparticle catalyst are comparable to the large pore mesoporous silica materials and faster than the small pore MCM-48 material with 22 Å diameter pores. A significant effect of the acidity of the magnetic nanoparticle support on catalyst activity in the Knoevenagel condensation is also observed.

Article Outline

1. Introduction
2. Experimental
2.1. Materials and instrumentation
2.2. Synthesis of magnetic nanoparticles
2.3. Amino-functionalized magnetic nanoparticles
2.4. Synthesis of SBA-15 and amino-functionalized SBA-15
2.5. Synthesis of MCM-48 and amino-functionalized MCM-48
2.6. Catalytic studies
3. Results and discussion
3.1. Catalyst synthesis and characterization
3.2. Catalytic studies
4. Conclusions
Acknowledgements
References

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