Selective catalytic reduction of NO over Co/beta-zeolite: effects of synthesis condition of beta-zeolites, Co precursor, Co loading method and reductant

The effects of preparation method for beta-zeolite, Co-precursor, loading method and different type of reductants on the performance of Co/beta-zeolite catalyst for HC-selective catalytic reduction (SCR) of NO have been investigated. The catalyst properties and nature of active sites have been characterized by N2 adsorption–desorption isotherms, X-ray diffraction (XRD), thermogravimetric analysis (TGA), TPR, X-ray photoelectron spectroscopy (XPS) and NMR. The catalyst activity is not affected by the type of cobalt precursor but is significantly influenced by the cobalt loading methods. The ion-exchange method results in a much higher activity than impregnation method. Although there is little influence of the silica source on the catalyst properties, the preparation condition of support beta-zeolite is found to substantially affect the activity of the resulting catalyst. The low hydrothermal synthesis temperature causes the presence of amorphous mesoporous phase, making the resulting catalyst poorly resistant to steam. The catalytic performance is substantially affected by different reductants used, with propane performing as a proper reductant for SCR of NO.