Method of preparing metal or metal oxide doped oxide catalysts having high deNOx selectivity for lean NOx exhaust aftertreatment systems

A lean NOx catalyst and method of preparing the same is disclosed. The lean NOx catalyst includes a substrate, an oxide support material, preferably gamma-alumina deposited on the substrate and a metal or metal oxide promoter or dopant introduced into the oxide support material. The metal promoters or dopants are selected from the group consisting of indium, gallium, tin, silver, germanium, gold, nickel, cobalt, copper, iron, manganese, molybdenum, chromium, cerium, and vanadium, and oxides thereof, and any combinations thereof. The gamma-alumina preferably has a pore volume of from about 0.5 to about 2.0 cc/g; a surface area of between 80 and 350 m /g; an average pore size diameter of between about 3 to 30 nm; and an impurity level of less than or equal to about 0.2 weight percent. In a preferred embodiment the gamma-alumina is prepared by a sol-gel method, with the metal doping of the gamma-alumina preferably accomplished using an incipient wetness impregnation technique.