Automotive catalytic converters: current status and some perspectives

The utilization of ceria in industrial catalysis

Plasma assisted combustion: Dynamics and chemistry

The oxidation of soot: a review of experiments, mechanisms and models

Diesel engine exhaust gas recirculation--a review on advanced and novel concepts

A flow-through ceramic monolithic catalyst, containing bulk CeO 2 as the catalytically active component, is reported for the catalytic oxidation of the liquid portion of the particulates present in diesel engine exhausts. This new technology has been successfully implemented into medium duty trucks in the U.S. beginning in 1994 meeting all required emission standards. Catalyst screening and engine durability/aging results and a proposed mechanism of operation are presented. The addition of a proprietary zeolite as a hydrocarbon trap and a small amount of Pt to the platform CeO 2 catalyst enables european emission standards for CO, HC and particulates to be met. Commercialization of this technology in Europe began in the first part of 1996.

Monolithic diesel oxidation catalysts

Oxidation catalyst compositions for treating diesel exhaust include ceria and, optionally, alumina, each having a surface area of at least about 10 m 2 /g, and a zeolite, e.g., Beta zeolite. Optionally, platinum may be included in the catalytic material, preferably in amounts which are sufficient to promote some gas-phase oxidation of carbon monoxide (“CO”) and hydrocarbons (“HC”) but which are limited to preclude excessive oxidation of SO 2 to SO 3 . Alternatively, palladium in any desired amount may be included in the catalytic material. The zeolite is optionally doped, e.g., ion-exchanged, with one or more of hydrogen, a platinum group metal or other catalytic metals. The catalyst compositions may be used in a method to treat diesel engine exhaust by contacting the hot exhaust with the catalyst composition to promote the oxidation of gas-phase CO and HC and of the volatile organic fraction component of particulates in the exhaust.

Zeolite-containing oxidation catalyst and method of use

The invention provides a catalyzed soot filter formed on a wall flow substrate having internal walls coated with catalyst compositions. A first catalytic coating is disposed on the internal walls of the wall flow filter substrate from the outlet end to a first coating end and extending for at least part of the length of the wall flow substrate and comprises a first co-formed ceria-zirconia-praseodymia composite and a first refractory metal oxide. A second catalyst coating is disposed on the internal walls of the wall flow substrate from the inlet end to a second coating end, thereby defining an inlet zone, wherein the inlet zone is no more than 50% of the length of the wall-flow substrate; wherein the second catalyst coating comprises a second platinum group metal component.

Pressure-balanced, catalyzed soot filter

A highly reactive reducing gas mixture is produced from vehicle fuel and introduced into the exhaust gas of an internal combustion engine operated at lean burn conditions and passed over a reducing catalyst to convert NOx emissions to benign emissions Preferably, fuel with oxygen present in a carrier gas is metered into a plasma reactor having a bed of dielectric particles which prevent formation of coke as the fuel is reacted The plasma induces a number of simultaneous reactions with the fuel to produce a substantial amount of oxygenated and non-oxygenated, unbranched organic molecules at relatively low temperatures that are highly reactive and ideally suited for use as a reducing agent in an SCR catalyst

Plasma fuel processing for NOx control of lean burn engines

Oxidation catalyst compositions include a catalytic material containing ceria and alumina each having a surface area of at least about 10 m2 /g, for example, ceria and activated alumina in a weight ratio of from about 1.5:1 to 1:1.5. Optionally, platinum may be included in the catalytic material in amounts which are sufficient to promote gas phase oxidation of CO and HC but which are limited to preclude excessive oxidation of SO2 to SO3. Alternatively, palladium in any desired amount may be included in the catalytic material. The catalyst compositions have utility as oxidation catalysts for pollution abatement of exhausts contianing unburned fuel or oil. For example, the catalyst compositions may be used in a method to treat diesel engine exhaust by contacting the hot exhaust with the catalyst composition to promote the oxidation of the volatile organic fraction component of particulates in the exhaust.

Kenneth E. Voss

Papers

Monolithic diesel oxidation catalysts

Zeolite-containing oxidation catalyst and method of use

Pressure-balanced, catalyzed soot filter

Plasma fuel processing for NOx control of lean burn engines

Ceria-alumina oxidation catalyst