Novel promoting effect of acid modification on selective catalytic reduction of NO with ammonia over CeO2 catalyst

• The NO conversion over CeO2 is obviously enhanced by the addition of solid acid.
• The introduction of solid acid increases the acid strength of CeO2.
• The addition of solid acid improves the distribution of Brønsted and Lewis acids.
• The existence of Brønsted acid contributes to the excellent N2 selectivity.
• The existence of weak and medium acids contributes to the superior SCR performance.

A series of acid modified CeO2 catalysts were prepared and used for selective catalytic reduction (SCR) of NO with NH3. The results showed that the SCR activity of pure CeO2 was greatly enhanced by the modification of acid. The CeO2 modified by 20% phosphotungstic acid exhibited the best NO conversion in a wide temperature range of 150–550 °C. The SCR activity was slightly influenced by SO2 and H2O, while such effect was reversible. The improvement of SCR activity and N2 selectivity over CeO2 catalyst modified by acid was attributed to the enhanced amount and intensity of Brønsted or Lewis acid sites.

The CeO2 catalysts modified by solid acid show high NO conversion for the NH3 selective catalytic reduction of NO at the space velocity of 60,000 h− 1. Furthermore, the catalyst modified by phosphotungstic acid exhibits the excellent N2 selectivity and the best activity in a wide temperature range of 150–525 °C. These were due to the enhanced amount and intensity of Brønsted or Lewis acid sites.Figure optionsDownload as PowerPoint slide