NOVELTY - Emission treatment system (3) downstream of a gasoline direct injection engine for treatment of an exhaust stream comprising hydrocarbons, carbon monoxide, nitrogen oxides and particulates, comprises a close-coupled three-way conversion (TWC) composite comprising a first TWC catalytic material (9) on a flow-through substrate, and an catalyzed particulate filter located downstream of the close-coupled TWC composite, where the filter comprises a second TWC catalytic material that permeates walls of a particulate filter, and the second TWC comprises rhodium as the only platinum group metal.
USE - The emission treatment system is useful in downstream of a gasoline direct injection engine for treatment of an exhaust stream comprising hydrocarbons, carbon monoxide, nitrogen oxides and particulates, and a catalyzed particulate filter (all claimed).
ADVANTAGE - The The emission treatment system provides a four-way converter formulation for underfloor position that only utilizes a monometallic platinum group metal, rhodium, as active precious metal, avoids completely the use of palladium, and is cost effective.
DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:
(1) a catalyzed particulate filter located in the emission treatment system downstream of a gasoline direct injection engine for treatment of an exhaust stream comprising hydrocarbons, carbon monoxide, nitrogen oxides, and particulates and downstream of TWC composite comprising a first TWC catalytic material on a flow-though substrate, comprising a particulate filter comprising a wall thickness of 6 mils (152 mu m) to 14 mils (356 mu m) and a porosity of 55-70%, and the second TWC catalytic material of 0.17-5 g/in3 (10-300 g/l), where the catalyzed particulate filter has a coated porosity that is less than an uncoated porosity of the particulate filter and a coated backpressure that is substantially the same as an uncoated backpressure of the particulate filter;
(2) treating an exhaust gas comprising hydrocarbons, carbon monoxide, nitrogen oxides and particulates, comprising obtaining the catalyzed particulate filter, and locating the catalyzed particulate filter downstream of a gasoline direct injection engine and the TWC composite comprising a first TWC catalytic material on a flow-through substrate, where upon operation of the engine, exhaust gas from the gasoline direct injection engine contacts the catalyzed particulate filter; and
(3) making emission treatment system for a gasoline direct injection engine, comprising positioning the TWC composite comprising a first TWC catalytic material on a flow-through substrate downstream of the gasoline direct injection engine, obtaining a catalyzed particulate filter comprising the second TWC catalytic material permeating walls of the particulate filter, and positioning the catalyzed particulate filter downstream of the TWC composite.
DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of the engine emission treatment system.
Emissions treatment system (3)
Gasoline engine (5)
Line that conveys exhaust through to the first three-way conversion catalyst (7)
First three-way conversion catalyst (9)
Downstream three-way conversion-coated particulate filter (13)
