Abstract: The nitric oxide (NO) and nitrogen dioxide (NO2) content of lean-burn engine exhaust is beneficially prepared for selective catalytic reduction (SCR) of these oxides to nitrogen by two sidestream additions to the exhaust. An ozone-containing air stream is added to the exhaust to affect oxidation of NO to NO2. And a hydrocarbon(s) fuel constituent is added to a second humidified ozone-containing air stream and that mixture subjected to UV radiation. Strongly oxidizing hydroxyl radicals are formed by interaction of ozone, water, and UV radiation for reaction with the hydrocarbon. The resulting partially oxidized hydrocarbons (Pox) are added to the exhaust, providing effective reduction materials for the SCR of NO2 to nitrogen and water.

Abstract: A method of partially oxidizing an alcohol to an aldehyde or ketone comprises contacting a gas containing the alcohol with a solid catalyst containing molybdenum, preferably in a +6 oxidation state, and having a surface area of 10 m2/g or higher, preferably 100 m2/g or higher. The molybdenum is supported on a high surface area carrier. The alcohol is a primary or secondary alcohol and preferably contains from 1 to 6 carbon atoms. In a preferred embodiment, the alcohol is ethanol. NOx emissions from an internal combustion engine can be lowered by combining the product of partial oxidation with the exhaust stream before passing the exhaust mixture through a lean NOx catalyst.