| abstract |
The method for decomposing NO 2 into NO in the exhaust gas of a lean burn internal combustion engine includes zeolite, titania doped with tungsten, silica-titania, zirconia-titania, gamma-alumina, amorphous silica-alumina and any one of them. Contacting the acidic metal oxide selected from the group consisting of more than one kind with the gas mixture comprising the exhaust gas, over the course of the duty cycle, on average throughout the duty cycle, Adjusting the composition of the gas mixture by injecting hydrocarbons therein at a rate that changes the C1 hydrocarbon: nitrogen oxide ratio of the gas mixture in contact to 0.1 to 2.0; And the step of releasing the effluent gas directly into the atmosphere, optionally contacting the gas mixture first with a hydrocarbon oxidation catalyst. Comprising. |