Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (02): 491-498.doi: 10.3866/PKU.WHXB20110212

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Polyoxotungstate-Modified Zirconia Aerogel as a Solid Catalyst for Tetrahydrofuran Polymerization

ZHU Qing1, LIANG Li-Ping1,2, JIA Zhi-Qi1, GAO Chun-Guang1, ZHAO Yong-Xiang1   

  1. 1. School of Chemistry and Chemical Engineering, Engineering Research Center for Fine Chemicals of Ministry of Education, Shanxi University, Taiyuan 030006, P. R. China;
    2. School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, P. R. China
  • Received:2010-08-10 Revised:2010-11-23 Published:2011-01-25
  • Contact: LIANG Li-Ping, ZHAO Yong-Xiang E-mail:yxzhao@sxu.edu.cn, liangliping@sxu.edu.cn
  • Supported by:

    The project was supported by the Scientific and Technological Project of Shanxi Province, China (20090321059) and Industrial Technology Development Project of Development and Reform Commission of Shanxi Province, China (2009164).

Abstract:

Catalysts with different loadings (mass fractions from 5% to 45%) of tungstophosphoric acid (TPA) on zirconia were prepared by suspending zirconia aerogel in an ethanol solution of TPA, removing the solvent via evaporation, drying and then calcining the powder at 750 °C. These catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, FTIR spectroscopy of adsorbed Pyridine (Py-IR), and temperature programmed desorption of NH3 (NH3-TPD). The catalytic performances of these materials were examined for the polymerization of tetrahydrofuran (THF). The experimental results indicated that the strong interaction between TPA and zirconia retarded both the crystallization of zirconia and the destruction of the Keggin-unit of TPA. In these materials, the major tungsten species were found to be zirconia-anchored heteropolytungstates (with distorted intact and/or partially fragmented Keggin-units) and Zr-containing pseudo-heteropolyanions produced by the chemical bonding of Zr4+ with the WOx fragments from TPA decomposition as well as some amount of WO3. The catalysts showed both Brönsted and Lewis acidity, and the catalyst with 20% TPA loading had the highest total acidity and catalytic activity because of the monolayer coverage of the active species. Under the reaction conditions of 40 °C for 20 h, the most active catalyst, 20TPZ-750, gave a high polymer yield of 30.9%±2%. During recycling for 6 times, no obvious activity loss was observed.

Key words: Zirconia aerogel, Tungstophosphoric acid, Polyoxotungstate, Tetrahydrofuran, Polymerization

MSC2000: 

  • O643.3