Effect of organic acid assisted impregnation method on sulfated CeO2/Al2O3 catalyst for selective catalytic reduction of NO by NH3

The CeO₂/Al₂O₃ catalysts were prepared by organic acid assisted impregnation method and then sulfated by (NH₄)₂SO₄ impregnation method. The catalytic activity and K poisoning of catalysts were tested by the selective catalytic reduction of NO with NH₃. The experimental results show that the sulfated CeO₂/Al₂O₃ catalysts assisted by organic acids have a wider reaction temperature window than the one prepared by traditional aqueous impregnation method. In addition, the sulfated CeO₂/Al₂O₃ catalyst assisted by citric acid has the best resistance to K poisoning. Multiple characterizations indicate that the coordination effect between organic acids and Ce ions helps to obtain smaller CeO₂ nanoparticles and more adsorbed sulfates, which is conducive to improving the catalytic activity of sulfated CeO₂/Al₂O₃ catalyst. However, loading K causes an increase in the size of CeO₂ nanoparticles, which suppresses the surface acid sites and redox ability of CeO₂/Al₂O₃ catalyst and results in the decline of catalytic activity.

Graphical abstract

K poisoning mechanism for the sulfated CeO₂/Al₂O₃ assisted by organic acids in NH₃-SCR reaction