Selective catalytic reduction of NOx by NH3 on Cu-SAPO-34 catalysts: Influence of silicium content on the activity of calcined and hydrotreated samples

• Synthesis of SAPO-34 with different Si contents was reported.
• Higher thermal stability of SAPO-34 containing low Si content.
• Hydrothermal treatment at 850 °C enhances NO-SCR activity of Cu(0.6)SAPO-34(Si = 1.2%).
• SAPO-34 with low Si content is a better host zeolite for FAP-SCR automotive Diesel applications.

SAPO-34 zeolites with three different Si contents were prepared by hydrothermal synthesis and then around 0.6 wt% Cu was introduced by impregnation. The structure and morphology of the samples were characterised via XRD and SEM techniques, respectively. The acid properties of the different samples were investigated by NH3-TPD. Cu-SAPO-34, with the lowest Si content, exhibits the best efficiency, between 200 and 550 °C, in NH3-SCR of NO after ageing treatment under H2O vapour at 850 °C for 5 h. For the fast reaction, (NO/NO2), a better efficiency is only observed with respect to the catalyst having low Si content.

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