This review covers the literature through 1991 on nitric oxide catalysis as applied to automobile exhaust systems. Attention is given to the threeway catalyst system which simultaneously promotes the reduction of nitrogen oxides and the oxidation of carbon monoxide and hydrocarbons. These systems have been used on most passenger cars in the United States since 1982. Prior to 1980, emission control catalysts were oxidation catalysts, and reduction in exhaust nitric oxide was achieved using engine modifications (i.e., exhaust gas recirculation). This review focuses on catalytic control of NO, for gasoline-fueled vehicles (not diesels and alternate fuels) and primarily on developments reported since 1982. The term NO, refers to both NO and NOz. The reader is referred to an earlier publication by the author for a general review of automobile catalytic converters [1] and to a review by Egelhoff [2] on the nitric oxide literature through 1980. The recent literature on NO, reduction in lean exhaust is c...

Nitric oxide catalysis in automotive exhaust systems

Catalytic NOx Abatement Systems for Mobile Sources: From Three-Way to Lean Burn after-Treatment Technologies Pascal Granger* and Vasile I. Parvulescu* Unit e de Catalyse et de Chimie du Solide, UMR CNRS 8181, University of Lille 1, 59655 Villeneuve d’Ascq, France Department of Organic Chemistry, Biochemistry and Catalysis, University of Bucharest, Romania, 412 Regina Elisabeta Boulevard, Bucharest 030016, Romania

Catalytic NOx Abatement Systems for Mobile Sources: From Three-Way to Lean Burn after-Treatment Technologies

The use of structured catalysts in the chemical industry has been considered for years. Conventional fixed-bed reactors have some obvious disadvantages such as maldistributions of various kinds (including a nonuniform access of reactants to the catalytic surface), high pressure drop in the bed, etc. Structured catalysts are promising as far as elimination of these setbacks is concerned. Two basic kinds of structured catalysts can be distinguished: Structural packings covered with catalytically active material, similar in design to those used in distillation and absorption columns and/or static mixers. Good examples of catalysts of this kind are those offered by Sulzer, clearly developed by Sulzer column packings and static mixers. As in packed beds, there is an intensive radial convective mass transport over the entire cross-section of these packings. Structural packing catalysts and the reactors containing them are, however, not within the scope of this review. Monolithic catalysts are continuou...

Monoliths in Heterogeneous Catalysis

The conversion of methanol to hydrocarbons is a remarkable reaction. The mechanism involves C-C bond formation from C1 fragments generated in the presence of certain acidic catalysts and reagents. The precise nature of these reactive C1 species is unknown at present and is the subject of lively debate. The considerable diversity of current opinion will become apparent from the following account.

Hydrocarbons from Methanol

Catalytic automotive exhaust aftertreatment

Kinetic Study of Carbon Monoxide and Propylene Oxidation on Platinum Catalysts

A catalytic converter for use in a gaseous stream comprises cylindrical segments of monolithic ceramic impregnated with catalytically active materials, such as hydrocarbon and carbon monoxide conversion catalysts, axially spaced apart by greater than 1/4 inch within a cylindrical metal container, said container having a gas inlet upstream from said spaced apart segments and a gas outlet downstream therefrom and a plurality of spaced apart protruding fins attached to the outer circumference thereof.

Catalytic converter for removing noxious components from a gaseous stream

Gasoline from alcohols

Thermal Response and Emission Breakthrough of Platinum Monolithic Catalytic Converters

The invention comprises a device to determine either that abnormally high concentrations of unburned combustibles (unburned hydrocarbons and carbon monoxide) are present in an engine exhaust stream or that the emissions control catalyst temperature has exceeded normal levels, and an apparatus which prevents the flow of unburned combustibles into the emissions control catalylst bed and activates an alarm to the engine operator upon such determination.

Charles R. Morgan

Papers

Kinetic Study of Carbon Monoxide and Propylene Oxidation on Platinum Catalysts

Catalytic converter for removing noxious components from a gaseous stream

Gasoline from alcohols

Thermal Response and Emission Breakthrough of Platinum Monolithic Catalytic Converters

High temperature protectional apparatus for engine emissions catalytic converter