Acta Phys. -Chim. Sin. ›› 2004, Vol. 20 ›› Issue (12): 1459-1464.doi: 10.3866/PKU.WHXB20041212

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Catalytic Combustion of Soot over Cu-Mg/Al Composite Oxides

Yu Jun-Jie; Jiang Zheng; Kang Shou-Fang; Hao Zheng-Ping   

  1. Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085
  • Received:2004-05-11 Revised:2004-07-09 Published:2004-12-15
  • Contact: Hao Zheng-Ping

Abstract: Keeping the atomic ratio of nM2+/nM3+ at 3, series of CuMgAl-O oxides (wCuO=0%, 5%, 10%, 15%, 20%, 30%, 40%,denoted as (0, 5, 10, 15, 20, 30, 40)CMAO respectively) were derived from calcination of Cu substituted Mg/Al-mixed anionic clay precursors(CuMgAl-hydrotalites, CMA-HTs), which were synthesized by co-precipitation methods. XRD, TG-DSC, TPR and FT-IR were used to study the influences of the Cu, Mg content upon the properties of precursors and prepared catalysts. Mg could improve thermal stability of catalysts in some degree. With the increase of Cu content, the surface area of catalysts decreased. However, the surface area was not an important factor in soot catalytic combustion. Activity tests showed the calcination affected the activity of CMAO catalysts significantly, and that 15CMAO-800 was the optimal catalyst for soot catalytic combustion and the T10 and T50 were 336 ℃ and 409 ℃ respectively. Moreover, complete structures of hydrotalcite precursors could be formed when wCuO≤30%. However, Cu(OH)2 phase appeared when wCuO =40%. When wCuO < 20%, homogeneous composite oxides could be obtained by calcination at 800 ℃, but CuO phase was isolated when wCuO≥20%. TG-DTA and FT-IR showed that the content of Cu, Mg had significant influences on the thermal decomposition characteristics of CuMgAl-hydrotalcites. TPR results showed that the reduction ability of catalysts was determined by the calcination and composition.

Key words: Hydrotalcite precursors,  Composite oxides,  Diesel exhaust,  Soot,  Catalytic combustion