A direct sulfation method for introducing the transition metal cation Co2+ into ZrO2 with little change in the Brønsted acid sites

Direct sulfation of Zr–Co hydroxides provides a significant advantage over traditional impregnation by conserving Brønsted acid sites for the introduction of a second active component and also for subsequent catalytic reactions. After Pd loading, sulfated Zr–Co exhibits excellent activity, selectivity, and durability for the selective catalytic reduction of NOx by methane. Using Co K-edge X-ray absorption spectroscopy, we provide the direct evidence of the entrance of Co into the lattice of cubic zirconia to form a substitutional solid solution.