Cerium dioxide (CeO2, ceria) is becoming an ubiquitous constituent in catalytic systems for a variety of applications. 2016 sees the 40th anniversary since ceria was first employed by Ford Motor Company as an oxygen storage component in car converters, to become in the years since its inception an irreplaceable component in three-way catalysts (TWCs). Apart from this well-established use, ceria is looming as a catalyst component for a wide range of catalytic applications. For some of these, such as fuel cells, CeO2-based materials have almost reached the market stage, while for some other catalytic reactions, such as reforming processes, photocatalysis, water-gas shift reaction, thermochemical water splitting, and organic reactions, ceria is emerging as a unique material, holding great promise for future market breakthroughs. While much knowledge about the fundamental characteristics of CeO2-based materials has already been acquired, new characterization techniques and powerful theoretical methods are dee...

Fundamentals and Catalytic Applications of CeO2-Based Materials

Catalytic removal of NO

Removal of nitrogen monoxide from exhaust gases through novel catalytic processes

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

Automotive exhaust catalysis

This catalyst system simultaneously removes ammonia and enhances net NOx conversion by placing an NH 3 -SCR catalyst formulation downstream of a lean NOx trap. By doing so, the NH 3 -SCR catalyst adsorbs the ammonia from the upstream lean NOx trap generated during the rich pulses. The stored ammonia then reacts with the NOx emitted from the upstream lean NOx trap—enhancing the net NOx conversion rate significantly, while depleting the stored ammonia. By combining the lean NOx trap with the NH 3 -SCR catalyst, the system allows for the reduction or elimination of NH 3 and NOx slip, reduction in NOx spikes and thus an improved net NOx conversion during lean and rich operation.

Haren S. Gandhi

Papers

Catalyst system for the reduction of NOx and NH3 emissions

The oxidation of CO by O2 and by NO on supported chromium oxide and other metal oxide catalysts

Effects of sulphur on noble metal automotive catalysts

The effects of SO2 on the oxidation of hydrocarbons and carbon monoxide over Ptγ-Al2O3 catalysts

The Origin of SO2 Promotion of Propane Oxidation over Pt/Al2O3 Catalysts