Method for purification of lean-burn engine exhaust gas

摘要

A dual-phase zeolite having a transition metal-containing zeolite phase and a transition metal-containing oxide phase. The catalytic material may be an intimate mixture of a phase-layered structure of a first phase constituted preferably of a copper-containing high silica zeolite and a second phase constituted of copper-containing zirconia. Methods are also disclosed for making a single-stage catalyst for removing NOx and HC at high efficiency in an oxygen-rich automotive exhaust gas, and for treating the exhaust gas with the dual-phase catalyst above.