Selective catalytic reduction of NO sub(x) by NH sub(3) on Cu-SAPO-34 catalysts: Influence of silicium content on the activity of calcined and hydrotreated samples

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 NH sub(3)-TPD. Cu-SAPO-34, with the lowest Si content, exhibits the best efficiency, between 200 and 550 degree C, in NH sub(3)-SCR of NO after ageing treatment under H sub(2)O vapour at 850 degree C for 5 h. For the fast reaction, (NO/NO sub(2)), a better efficiency is only observed with respect to the catalyst having low Si content.