Probing into the catalytic nature of Co/sulfated zirconia for selective reduction of NO with methane

In this work, the structural and surface properties of Co-loaded sulfated zirconia (SZ) catalysts were studied by X-ray diffraction (XRD), N2 adsorption, NH3-TPD, FT-IR spectroscopy, H2-TPR, UV–vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and NO-TPD. NH3-TPD and FT-IR spectra results of the catalysts showed that the sulfation process of the support resulted in the generation of strong Brønsted and Lewis acid sites, which is essential for the SCR of NO with methane. On the other hand, the N2 adsorption, H2-TPR, UV/vis DRS, and XPS of the catalysts demonstrated that the presence of the SO42− species promoted the dispersion of the Co species and prevented the formation of Co3O4. Such an increased dispersion of Co species suppressed the combustion reaction of CH4 by O2 and increased the selectivity toward NO reduction. The NO-TPD proved that the loading of Co increased the adsorption of NO over SZ catalysts, which is another reason for the promoting effect of Co.