Patent ID: 8151742
Filing Date: 2012-04-10
Classification: B01D,B01J,C01B,F01N,Y02A,Y02P

Abstract:
1. An exhaust gas cleaner used in exhaust gas purification of an internal combustion engine in which fuel is supplied under periodical rich or lean conditions, and caused to combust, the exhaust gas cleaner comprising: a reforming means, which is provided independently to be separate from an exhaust channel, for producing a reformed gas containing hydrogen and carbon monoxide, and introducing into the exhaust channel of the internal combustion engine; a low temperature oxidation means, which is provided inside the exhaust channel on a side further downstream than an introduction portion at which reformed gas is introduced by the reforming means, for oxidizing and adsorbing nitrogen oxides at a lower temperature than when the reforming means is not provided as well as oxidizing hydrogen and carbon monoxide, and for releasing nitrogen oxides adsorbed when 130° C. has been exceeded; a purifying means, which is provided inside the exhaust channel on a side further downstream than the low temperature oxidation means, for adsorbing nitrogen oxides in a lean condition as well as releasing nitrogen oxides thus adsorbed in a rich condition, and for purifying nitrogen oxides thus released by employing hydrogen and carbon monoxide existing inside the exhaust channel; and an introduction means for directly introducing reformed gas produced by the reforming means to the purifying means, wherein the reforming means includes at least one type of metallic catalyst component selected from the group consisting of rhodium, platinum, palladium, nickel, cobalt, and iron, and a carrier oxide containing at least one type of oxide selected from the group consisting of ceria, alumina, zirconia, titania, magnesia, and zeolite, or a complex oxide, wherein the low temperature oxidation means includes palladium, and at least one type of a carrier oxide component selected from the group consisting of alumina, silica, zirconia, titania, ceria, and zeolite, and at least one element selected from the group consisting of lanthanum, praseodymium, yttrium, and neodymium is added to the carrier oxide component, wherein the purifying means includes: a catalyst component A containing (a) ceria, (b) praseodymium oxide, or (c) a mixture of oxides and/or a complex oxide of at least two elements selected from the group consisting of cerium, zirconium, praseodymium, neodymium, terbium, samarium, gadolinium, and lanthanum, a catalyst component B containing at least one (d) noble metal catalyst component selected from the group consisting of platinum, rhodium, palladium, and oxides thereof, and a catalyst component C containing either one or both of (e) a solid acid and (f) a solid acid on which an oxide of at least one metal selected from the group consisting of vanadium, tungsten, molybdenum, copper, iron, cobalt, nickel, and manganese is loaded, and wherein the catalyst component B is dispersed on the catalyst component A.