催化学报 ›› 2014, Vol. 35 ›› Issue (7): 1136-1147.DOI: 10.1016/S1872-2067(14)60060-7

• 论文 • 上一篇    下一篇

Zirconium phosphate nanoparticles as a remarkable solid acid catalyst for selective solvent-free alkylation of phenol

Abdol R. Hajipoura,b, Hirbod Karimia   

  1. a. Pharmaceutical Research Laboratory, Department of Chemistry, Isfahan University of Technology, Isfahan 84156, IR Iran;
    b. Department of Neuroscience, University of Wisconsin, Medical School, Madison, WI 53706-1532, USA
  • 收稿日期:2013-12-06 修回日期:2014-02-20 出版日期:2014-06-28 发布日期:2014-06-28
  • 通讯作者: Abdol R. Hajipour

Zirconium phosphate nanoparticles as a remarkable solid acid catalyst for selective solvent-free alkylation of phenol

Abdol R. Hajipoura,b, Hirbod Karimia   

  1. a. Pharmaceutical Research Laboratory, Department of Chemistry, Isfahan University of Technology, Isfahan 84156, IR Iran;
    b. Department of Neuroscience, University of Wisconsin, Medical School, Madison, WI 53706-1532, USA
  • Received:2013-12-06 Revised:2014-02-20 Online:2014-06-28 Published:2014-06-28

摘要:

A facile synthesis of α-zirconium phosphate (ZP) nanoparticles as an effective, eco-friendly, and recyclable solid acid catalyst is reported. Polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) were used as organic matrix as dispersing agents and served as a template for the nanoparticles. Hydrogen bonds between ZP and PVA or PVP, along the polymer chains, appear to play an important role for improving the dispersion of in situ formed ZP. Following calcination of PVA/ZP or PVP/ZP, pure hexagonal ZP nanoparticles were obtained. The catalysts were characterized by nitrogen sorption, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and transmission electron microscopy. Pyridine-FTIR and temperature-programmed desorption of NH3 suggest the presence of Brönsted acid sites. The acidic properties of the catalyst were studied in Friedel-Crafts alkylation of phenol by tert-butanol, producing 2-tert-butylphenol, 4-tert-butylphenol, and 2,4-di-tert-butylphenol. The alkylation reaction was performed in the presence of catalysts P2O5/Al2O3, P2O5/SiO2, α-ZrP (prepared in the absence of the polymers), and various ionic liquids. The use of the hexagonal ZP nanoparticle catalyst afforded an excellent phenol conversion (86%) and selectivity towards 4-tert-butylphenol (83%) under optimized reaction conditions. The catalyst was easily recovered from the reaction mixture, regenerated, and reused at least four times without significant loss in the catalytic activity.

关键词: Hexagonal zirconium phosphate, Nanoparticle, Solvent free, Phenol alkylation, eterogeneous catalyst, Polyvinyl alcohol, Polyvinylpyrrolidone

Abstract:

A facile synthesis of α-zirconium phosphate (ZP) nanoparticles as an effective, eco-friendly, and recyclable solid acid catalyst is reported. Polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) were used as organic matrix as dispersing agents and served as a template for the nanoparticles. Hydrogen bonds between ZP and PVA or PVP, along the polymer chains, appear to play an important role for improving the dispersion of in situ formed ZP. Following calcination of PVA/ZP or PVP/ZP, pure hexagonal ZP nanoparticles were obtained. The catalysts were characterized by nitrogen sorption, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and transmission electron microscopy. Pyridine-FTIR and temperature-programmed desorption of NH3 suggest the presence of Brönsted acid sites. The acidic properties of the catalyst were studied in Friedel-Crafts alkylation of phenol by tert-butanol, producing 2-tert-butylphenol, 4-tert-butylphenol, and 2,4-di-tert-butylphenol. The alkylation reaction was performed in the presence of catalysts P2O5/Al2O3, P2O5/SiO2, α-ZrP (prepared in the absence of the polymers), and various ionic liquids. The use of the hexagonal ZP nanoparticle catalyst afforded an excellent phenol conversion (86%) and selectivity towards 4-tert-butylphenol (83%) under optimized reaction conditions. The catalyst was easily recovered from the reaction mixture, regenerated, and reused at least four times without significant loss in the catalytic activity.

Key words: Hexagonal zirconium phosphate, Nanoparticle, Solvent free, Phenol alkylation, eterogeneous catalyst, Polyvinyl alcohol, Polyvinylpyrrolidone