Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Solid component
Reexamination Certificate
2002-04-22
2004-07-20
Stoner, Kiley (Department: 1725)
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Solid component
C423S213200, C423S213500, C502S325000, C502S328000, C502S330000, C502S339000, C502S344000, C502S355000
Reexamination Certificate
active
06764664
ABSTRACT:
TECHNICAL FIELD
This disclosure relates to the purification of contaminants and particulates from exhaust gases. More particularly, this disclosure relates to a catalyst composition for exhaust gas purification, including soot combustion.
BACKGROUND OF THE DISCLOSURE
In order to meet exhaust gas emission standards, the exhaust emitted from internal combustion engines is treated prior to emission into the atmosphere. Exhaust is passed through a catalytic element to remove undesirable gaseous emission components such as unburned hydrocarbons, carbon monoxide and nitrogen oxides. In addition to the gaseous components, exhaust gases also contain particulate matter such as carbon-containing particles or soot. A particulate filter, also commonly used with compression ignition engines, is used to prevent soot, or carbon particles, from exiting the tailpipe. Carbon particles are stored in the filter and then burned so that the filter is regenerated and able to again store the carbon particles. In a passive diesel particulate filter, the filter becomes so filled with particulate matter that the heat accumulated due to increased vehicle speed or load raises the temperature of the carbon to a temperature at which it ignites.
In the process to develop a catalyzed diesel particulate filter, it has been shown that eutectic salts such as KVO
3
(potassium vanadate) and CsVO
3
(cesium vanadate) are efficient diesel soot oxidation catalysts which provide lower soot ignition temperatures and higher soot combustion rates than other catalysts. These eutectic salts perform well as catalysts because of their low melting points, 520° C. for KVO
3
and 641° C. for CsVO
3
(see, for example, U.S. Pat. No. 4,515,758 to Domelse et al.). The low melting temperature of the eutectic salts causes them to be partially melted when the soot burns and this partial melting results in more efficient contact with the soot and thus efficient combustion. The low melting point of these eutectic salts, however, causes them to have high mobility when coated on a wall-flow diesel particulate filter. Under diesel engine exhaust treatment conditions, lack of durability as evidenced by loss of adhesion of the catalyst is a significant problem.
There thus remains a need for catalyst formulations for catalyzed diesel particulate filters that have good catalytic properties and low soot ignition temperatures.
The above described and other features are exemplified by the following figures and detailed description.
SUMMARY OF THE DISCLOSURE
Disclosed herein is a method for preparing a catalyst composition comprising: preparing; combining an alkali metal aluminate precursor and a catalytic metal salt to form a mixture; and calcining the mixture to form an alkali metal aluminate comprising a substantially uniformly dispersed alkali metal catalytic metal oxide. Also disclosed is a process treating diesel soot, comprising contacting the soot with an alkali metal aluminate comprising a substantially uniformly dispersed alkali metal catalytic metal oxide.
REFERENCES:
patent: 4515758 (1985-05-01), Domesle et al.
patent: 5146013 (1992-09-01), Dogimont et al.
patent: 5536695 (1996-07-01), Blejean et al.
patent: 5614596 (1997-03-01), Laine et al.
patent: 5853675 (1998-12-01), Howorth
patent: 5885917 (1999-03-01), Ohdan et al.
patent: 5939354 (1999-08-01), Golden
patent: 5977017 (1999-11-01), Golden
patent: 6013599 (2000-01-01), Manson
patent: 6248689 (2001-06-01), Manson
patent: 6352955 (2002-03-01), Golden
patent: 6372686 (2002-04-01), Golden
patent: 6498280 (2002-12-01), Uzio et al.
patent: 8-173770 (1996-07-01), None
Joint Committee of Powder Diffraction Standars (JCPDS), International Center for Diffraction, card No. 29-0820, no date available.
Waldner, et al. “Synthesis of a Double Alkoxide Precursor to Spinel (MgAL204) Directly from AI (OH)3, MgO, and Triethanolamine and Its Pyrolytic Transformation to Spinel” Chem. Material., vol. 8, No. 12, pp. 2850-2857 (1996).
H.R. Hoekstra, et al., “Synthesis of Pyrochlore-Type Oxides of Platinum (IV) at High Pressure”, Inorganic Chemistry, vol. 7, No. 12, Dec. 1968, Received Jul. 11, 1968, pp. 2553-2557.
Y. Nishihata, et al., “Self-regeneration of a Pd-perovskite catalyst for automotive emissions control”, Letters to Nature, vol. 418, Jul. 11, 2002, pp. 164-167.
Magdalena Helmer, “Cleaning up Catalysts”, Nature, vol. 418, Jul. 11, 2002, p. 138.
Delphi Technologies Inc.
Ildebrando Christina
Marshall Paul L.
Stoner Kiley
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