Migration of the Cu species by alkali metal potassium on the reaction of NH3 with NOx over Cu-SSZ-13 catalyst

•Cu/SSZ-13 catalyst showed a narrow T80 windows after the impregnation high amount of potassium.•High amount of potassium promoted the migration of stable Cu2+ to the CuO species.•The formation of CuO species on the catalysts may gradually block the molecular sieve channels.•The migration of Cu2+ to CuO species contributed to the NH3-SCR activity of the catalyst declined at high temperature.