Reduced-emissions combustion utilizing multiple-component metallic combustion catalyst and lightly catalyzed diesel particulate filter

Abstract

An improved, robust diesel emission control system employs a lightly diesel particulate filter (DPF), preferably with a platinum containing fuel borne catalyst (FBC) in the fuel. The DPF is preferably of wire mesh construction and at least partially lightly catalyzed with precious metal catalyst, e.g., platinum group metal, having a metal loading of from about 3 to 15 grams per cubic foot to minimize formation of NO2 in the exhaust gas. Preferred fuel borne catalyst levels will be low, e.g., from 0.05 to 0.5 ppm for platinum and 3 to 8 ppm for cerium and / or iron, thereby providing effective engine out emissions reductions without discharging excessive amounts of NO2 to the atmosphere.

Description

RELATED APPLICATIONS AND PRIORITY [0001] This is a continuation in part of and claims priority to pending U.S. patent application Ser. No. 10 / 306,954 filed 29 Nov. 2002, which claims priority to U.S. Provisional Patent Application No. 60 / 354,435 filed 04 Feb. 2002 (hereinafter, both referred to as priority applications).BACKGROUND OF THE INVENTION [0002] The invention concerns a new process for to reduce emission of pollutants of the type generated by incomplete combustion, e.g., particulates, unburned hydrocarbons and carbon monoxide, while avoiding increasing the production of NO2. [0003] Diesel engines have a number of important advantages over engines of the Otto type. Among them are fuel economy, ease of repair and long life. From the standpoint of emissions, however, they present problems more severe than their spark-ignition counterparts. Emission problems relate to particulate matter (PM), nitrogen oxides (NOx), unburned hydrocarbons (HC) and carbon monoxide (CO). NOx is a t...

AI Technical Summary

Benefits of technology

[0011] It is another object of the invention to provide a system that can reduce system costs by lowering the requirements for platinum catalyst while maintaining the apparent benefit of NO2 as an aid to soot oxidation in a DPF.

[0012] It is yet another object of the invention to provide an effective diesel particulate reduction system that provides good PM reduction efficiency while minimizing the use of precious metals and reducing the quantity of NO2 emitted from the exhaust.

[0013] A yet further object of the invention is to provide an emissions control system that is durable and able to oxidize soot at low exhaust temperatures without a need for frequent cleaning.

[0014] It is yet another and specific object of the invention to fill a need in the art for a system for emissions control for diesel engines which is based on the recognition of adverse effects of excessive catalyst loading on a DPF support and thereby enables a new balance to be achieved between the level of PM reduced and cost, durability, secondary emissions and maintenance intervals.

Problems solved by technology

From the standpoint of emissions, however, they present problems more severe than their spark-ignition counterparts.

In all cases, they are expensive due in significant part to the cost of precious metals used required to be effective.

A result of this approach is large quantities of excess NO2 escaping the system.

However, in this type of system, the art finds it necessary to utilize high platinum loadings to achieve satisfactory regeneration despite the high cost of the platinum and the associated problems of NO2 emission.

It does not address the high cost of platinum related to the Cooper system or the adverse effect of NO2 emissions.