The performance of various noble metal based catalysts for the NOxreduction in the CO-rich conditions of simulated post Euro-IV diesel emissions at low temperature was investigated in this paper. Pd loaded catalyst showed higher catalytic activity than Ir or Rh loaded catalysts. Titania, as one of the support material, clearly promoted the deNOxprocess due to the synergy with alumina and Palladium. The TiO2loading was optimized subsequently. As a result, Pd/TiO2/Al2O3catalyst with Pd loading of 2.0 wt.% and TiO2loading of 10 wt.% showed the NOxconversions of 25~46% in the temperature range of 200~250°C.
The performance of Pd/TiO2/Al2O3 catalyst for the NOx reduction in the CO-rich conditions of simulated post Euro-IV diesel emissions at low temperature was investigated in this paper. The addition of a small amount of H2 resulted in a visible synergetic effect. And the total amount of mixed reductant also improved the NOx convertion. The catalyst showed NOx conversions exceed 40% at 100~250°C when the reductant amount is 8,000 ppm with the H2/CO ratio of 1:3, where water vapor is absence. Even though water vapor had a negative influence, 25~33% of NOx can be decomposed using this catalyst, which is meaningful considering that it is used in a passive system.
The catalytic selective reduction of NOxwith CO over Pd/Al2O3and Pd/TiO2/Al2O3under lean conditions (called SCR-deNOxin simple way) was studied here. The performance of the catalysts with different Pd loadings for deNOxwas investigated. The results showed that the 2.0 wt.% Pd/TiO2/Al2O3and 1.5 wt.% Pd/Al2O3catalysts displayed optimum deNOxactivities of 46% and 20% at 200°C, respectively. TEM, XRD, XPS and SEM were utilized to characterize the catalysts. Metallic palladium is thought to be the active site which highly dispersed on the catalyst supports. The synergy between TiO2and Al2O3or Pd is thought to be the reason for the obvious improvement in deNOxprocess.
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