Acta Phys. -Chim. Sin. ›› 2007, Vol. 23 ›› Issue (11): 1738-1742.doi: 10.3866/PKU.WHXB20071116

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Performance of La-Ba Co-modified Alumina Prepared by Peptizing Method

ZHANG Li-Juan; DONG Wen-Ping; GUO Jia-Xiu; YUAN Shu-Hua; ZHANG Lei; GONG Mao-Chu; CHEN Yao-Qiang   

  1. College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
  • Received:2007-05-15 Revised:2007-06-20 Published:2007-11-01
  • Contact: CHEN Yao-Qiang

Abstract: La-Ba co-modified alumina was prepared from two kinds of pseudo boehmite and HNO3 as peptizer by peptizing method. The structure and surface property of the alumina were characterized by XRD, BET surface area analyzer, NH3-temperature programmed desorption and NO2-temperature programmed desorption technology. XRD results showed that γ-Al2O3 phase existed in all the modified alumina samples after calcination at 1273 K. A little BaCO3 was generated when content of BaO was increased to 14%(w). BET results showed that both of 5%(w) La2O3-modified and 5% La2O3-8%BaO co-modified alumina (Ba-8) samples exhibited larger specific surface area and pore volume after calcination at 1273 K. N2 adsorption and desorption isotherms of all alumina exhibited that their surface pore structure was slit-shape and ink-shape pores, pore diameter distribution of Ba-8 was broader and centered between 5 and 10 nm, and other samples centered at 10 nm. NH3-TPD results indicated that the larger the BaO doping concentration, the less the acidic amount was. At the same time, surface acidity of alumina apparently became weak. NO2-TPD results showed that BaO doped alumina adsorbed more NO2 than La2O3 doped, sample Ba-8 adsorbed the most NO2. As sample Ba-8 simultaneously exhibited good textural properties, proper surface acidic amount, acidity and stronger NO2 adsorption capacity, it had the best catalytic performance when it was used as catalyst carrier. The temperatures of light-off and complete conversion of C3H8 were 526 K and 593 K, respectively.

Key words: Alumina, Surface properties, Three-way catalyst, Low content of noble metal


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