Abstract:
The present invention relates to an article comprising a catalyst composition and a method useful for the removal of NOx and SOx contaminants from a gaseous stream, especially gaseous streams containing sulfur oxide contaminants. More specifically, the present invention is concerned with catalysts of the type generally referred to as nullclose coupled catalystsnull which are designed to reduce pollutants in engine exhaust emissions during engine cold start conditions. The article comprises a lean burn gasoline engine having an exhaust outlet, an upstream section having a close coupled catalyst composite in communication with the exhaust outlet, and a downstream section. The upstream close coupled catalyst composite comprises a first support; a first platinum group component; and a SOx sorbent component selected from the group consisting of oxides and mixed oxides of barium, lanthanum, magnesium, manganese, neodymium, praseodymium, and strontium. The downstream section comprises a second support; a second platinum group component; and a NOx sorbent component. The upstream section has substantially no components adversely affecting three-way conversion under operating conditions.
Abstract:
A catalytic trap disposed in an exhaust passage of an internal combustion engine which is operated with periodic alternations between lean and stoichiometric or rich conditions, for abatement of NOx in an exhaust gas stream which is generated by the engine. The trap comprises a catalytic trap material and a refractory carrier member on which the catalytic trap material is disposed. The catalytic trap material comprises: (i) a refractory metal oxide support; (ii) a catalytic component effective for promoting the reduction of NOx under stoichiometric or rich conditions; and (iii) a NOx sorbent effective for adsorbing the NOx under lean conditions and desorbing and reducing the NOx to nitrogen under stoichiometric or rich conditions. The NOx sorbent comprises a metal oxide selected from the group consisting of one or alkali metal oxides, alkaline earth metal oxides and mixtures of one or more alkali metal oxides and alkaline earth metal oxides. The manganese component is selected from the group consisting of: (1) a manganese oxide, (2) a mixed oxide of manganese and a transition metal and/or a rare earth metal, (3) a compound of an alkali metal and a manganese oxide, (4) a compound of an alkaline earth metal and a manganese oxide and (5) mixtures of the foregoing oxides and compounds.
Abstract:
In order to increase the long-term stability of the exhaust catalyst of an internal combustion engine, the exhaust gas is purified with respect to volatile phosphorus compounds before entering the catalyst.