| abstract |
FIELD: engines and pumps. n SUBSTANCE: exhaust system comprises the first catalysed carrier monolith comprising the first thin-layer coating located in the first thin-layer area of the carrier monolith, where the thin-layer coating contains a catalytic composition containing at least one platinum group metal and at least one carrier material, wherein at least one platinum group metal in the first thin-layer coating is susceptible to volatilization, when the thin-layer coating is maintained at the temperature of ≥700°C, and the second thin-layer coating located in the second thin-layer area of the carrier monolith, wherein the second thin-layer coating contains at least one copper-carrying material for trapping the volatilized platinum group metal, wherein at least one carrier material represents at least one metal oxide, a molecular sieve, or a mixture of any two or more of them, and when at least one carrier material represents at least one metal oxide, at least one metal-oxide carrier is selected from the group consisting of optionally stabilised aluminium oxide, amorphous silicon dioxide-aluminium oxide, optionally stabilised zirconium oxide, titanium oxide, optionally stabilized mixed cerium oxide-zirconium oxide and mixtures of two or more of them, and wherein the second thin-layer coating is oriented to contact with the exhaust gas that had contact with the first thin-layer coating, and b) the second catalysed carrier monolith containing the catalyst to selectively catalyze the reduction of nitrogen oxides to molecular nitrogen with a nitrogen reductant, located downstream from the first catalysed carrier monolith. n EFFECT: preventing the volatilization of relatively low levels of platinum group metals from the components upstream of the SCR catalyst. n 19 cl, 5 dwg, 9 ex |