FTIR Studies of Urea Decomposition over Pt-Alumina and Cu-Alumina Catalysts


Yasyerli N. , Tasdemir M.

INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING, cilt.8, 2010 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 8
  • Basım Tarihi: 2010
  • Doi Numarası: 10.2202/1542-6580.2427
  • Dergi Adı: INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING

Özet

Urea, as an ammonia source, has been known to be a highly selective and efficient reducing agent to remove NO(x) from the automobile exhaust gases. Transition metals, such as Pt, Pd, Ag and Cu, on alumina are active and stable for the reduction of NO(x) by urea. In this study, urea decomposition was investigated over a 1% Cu and 2% Pt on alumina catalysts prepared by a single step sol-gel technique. Urea decomposition over these catalysts was studied in helium atmosphere in the range of 100-400 degrees C by using FTIR. The analysis of FTIR spectra gave information about NH(3) , NH(4)(+), CO(2) and isocyanate (CNO-) formation on 1% Cu/Al(2)O(3) and 2% Pt/Al(2)O(3) catalysts. OH and CH stretching vibration bands were also observed over these catalysts. Isocyanate peak was observed at 150 degrees C on 2% Pt/Al(2)O(3) catalyst. The corresponding peak was observed at 250 degrees C on 1% Cu/Al(2)O(3) catalyst. The peak corresponding to melamine was observed on 2% Pt/Al(2)O(3) at all the temperatures except for 150 degrees C. However, melamine peak was only detected on 1% Cu/Al(2)O(3) at 150 degrees C for two and four minutes. Reducing agents for NO(x) reduction were obtained over 1% Cu/Al(2)O(3) catalyst at high temperatures and over 2% Pt/Al(2)O(3) catalyst at low temperatures. It is concluded that the catalysts prepared using the sol-gel process are effective in the decomposition of urea as ammonia and isocyanate sources.