The Reduction of NO by CO in the Presence of Water Vapour on Supported Platinum Catalysts

Formation of Isocyanic Acid (HNCO) and Ammonia

Noel W. Cant*, Dean C. Chambers, Irene O Y Liu

*Corresponding author for this work

Research output: Contribution to journalArticle

30 Citations (Scopus)


The reaction of NO with excess CO in the presence of water vapour has been studied for silica- and alumina-supported platinum. With Pt/SiO2, HNCO is the dominant nitrogen-containing product between 300 and 400°C, with a yield of up to 50%. Higher temperatures favour NH3 formation due to HNCO hydrolysis and shifts in surface populations that can be interpreted in terms of the NO + CO and water-gas shift reactions. When excess water is present, the hydrolysis activity of Pt/Al2O3 is sufficient to convert all HNCO to NH3. The yield of NH3 exceeds 75% at temperatures above 280°C, where conversion of NO becomes complete. Insufficient water leads to the formation of Al-NCO groups and a loss of activity that can be reversed by additional water. Pt/CeO2 behaves similarly to Pt/Al2O3. Pd/SiO2 also generates some HNCO, but the concentrations made are much less than that over Pt/SiO2 due to a higher activity for the NO + CO reaction and a lower activity for the CO + H2O one.

Original languageEnglish
Pages (from-to)551-559
Number of pages9
JournalApplied Catalysis B: Environmental
Issue number3
Publication statusPublished - 28 Nov 2003


  • Ammonia formation
  • Isocyanic acid (HNCO)
  • NO reduction of CO
  • Pt/AlO
  • Pt/SiO

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