Patent ID: 7838461

Claim:
A monolith catalyst for purifying lean burn NOx emission obtained by applying a mesoporous catalyst to gas channel inner walls of a monolith formed body, wherein the mesoporous catalyst comprises a mesoporous material and at least one of platinum and iridium, wherein the mesoporous material is a member selected from the group consisting of mesoporous borosilicate, mesoporous tungstosilicate, mesoporous niobosilicate, and mesoporous ceriumsilicate; wherein the respective amount of boron, tungsten, niobium, and cerium in the mesoporous borosilicate, mesoporous tungstosilicate, mesoporous niobosilicate and mesoporous ceriumsilicate is 1 to 20 mol % of the amount of silicon in the mesoporous material; and the mesoporous material substantially has pores with a diameter of 2 to 50 nm and a specific surface area of 100 to 1,400 m 2 /g, and has a through-hole pore structure expanding networkwise, and wherein 0.01 to 20 mass % of the mesoporous catalyst are nanoparticles of at least one of platinum and iridium having an average particle size of 1 to 20 nm as the main catalyst supported on the mesoporous material, wherein the catalyst has a NOx purification ratio of at least 39% at a temperature of 150° C.