초록 ▼

A method improves the operation of a diesel engine through the use of a fuel additive, a diesel particulate trap and a NO.sub.x -reducing catalyst. The operation of the NO.sub.x -reducing catalyst is enhanced by the introduction of urea or like compound upstream of the catalyst at temperatures effec

A method improves the operation of a diesel engine through the use of a fuel additive, a diesel particulate trap and a NO.sub.x -reducing catalyst. The operation of the NO.sub.x -reducing catalyst is enhanced by the introduction of urea or like compound upstream of the catalyst at temperatures effective for non-catalytic NO.sub.x reduction and the generation of ammonia. The additive comprises fuel-soluble compositions of platinum group metal in effective amounts to lower the emissions of unburned hydrocarbons and carbon monoxide from the trap. The catalytic activity provided to the exhaust system by the fuel additive is selective and preferably reduces the oxidation of SO.sub.2 to SO.sub.3. The platinum group metal compositions are preferably added in amounts effective to provide concentrations of the metal in the fuel of less than 1 part per million (ppm). Lithium and/or sodium compositions can be used in amounts effective to reduce the trap regeneration temperature, e.g. concentrations to provide about 1 to 100 ppm lithium metal, and/or 1 to 30 ppm sodium metal.

대표청구항 ▼

[ I claim:] [1.] A method for operating a diesel engine with reduced emissions of particulates and NO.sub.x, comprising:(a) adding to a diesel fuel, a fuel-soluble composition of platinum group metal in effective amounts such that the gases produced by combustion selectively catalyze the exhaust sys

[ I claim:] [1.] A method for operating a diesel engine with reduced emissions of particulates and NO.sub.x, comprising:(a) adding to a diesel fuel, a fuel-soluble composition of platinum group metal in effective amounts such that the gases produced by combustion selectively catalyze the exhaust system, including a particulate trap, effectively to lower the emissions of unburned hydrocarbons and carbon monoxide, said platinum group metal composition comprising a fuel soluble organic compound whichI) is resistant to breakdown under ambient temperatures;ii) is substantially free of phosphorus, arsenic, antimony, or halogens;iii) has a partition ratio sufficient to maintain preferential solubility in the fuel;iv) has a breakdown temperature of at least about 122.degree. F. andv) a partition ratio of at least about 25;(b) combusting the diesel fuel in a diesel engine resulting in the production of diesel combustion gases containing NO.sub.x and particulates;(c) injecting into the combustion gases within the cylinder of the diesel engine near the end of the power stroke where the temperature is within the range of from 1600.degree. and 2000.degree. F. an aqueous solution of a NO.sub.x -reducing composition which produces ammonia by the decomposition of the NO.sub.x -reducing composition selected from the group consisting of urea, cyanuric acid, dicyanimide, calcium cyanamide, and mixtures of these, the temperature being effective to reduce the level of NO.sub.x in the combustion gases and produce ammonia by the decomposition of the NO.sub.x -reducing composition;(d) passing the combustion gases containing ammonia through a particulate trap comprised of a gas permeable material to reduce the level of particulates; and(e) passing the combustion gases through a NO.sub.x -reduction catalyst to reduce NO.sub.x and ammonia produced by decomposition of the NO.sub.x -reducing composition.