Automotive catalytic converters: current status and some perspectives

Catalysts for chemical and electrochemical reactions underpin many aspects of modern technology and industry, from energy storage and conversion to toxic emissions abatement to chemical and materials synthesis. This role necessitates the design of highly active, stable, yet earth-abundant heterogeneous catalysts. In this Review, we present the perovskite oxide family as a basis for developing such catalysts for (electro)chemical conversions spanning carbon, nitrogen, and oxygen chemistries. A framework for rationalizing activity trends and guiding perovskite oxide catalyst design is described, followed by illustrations of how a robust understanding of perovskite electronic structure provides fundamental insights into activity, stability, and mechanism in oxygen electrocatalysis. We conclude by outlining how these insights open experimental and computational opportunities to expand the compositional and chemical reaction space for next-generation perovskite catalysts.

http://science.sciencemag.org/content/sci/358/6364/751.full.pdf

Perovskites in catalysis and electrocatalysis

Over the last several years, nitrogen oxide(s) (NOx) storage/reduction (NSR) catalysts, also referred to as NOx adsorbers or lean NOx traps, have been developed as an aftertreatment technology to reduce NOx emissions from lean‐burn power sources. NSR operation is cyclic: during the lean part of the cycle, NOx are trapped on the catalyst; intermittent rich excursions are used to reduce the NOx to N2 and restore the original catalyst surface; and lean operation then resumes. This review will describe the work carried out in characterizing, developing, and understanding this catalyst technology for application in mobile exhaust‐gas aftertreatment. The discussion will first encompass the reaction process fundamentals, which include five general steps involved in NOx reduction to N2 on NSR catalysts; NO oxidation, NO2 and NO sorption leading to nitrite and nitrate species, reductant evolution, NOx release, and finally NOx reduction to N2. Major unresolved issues and questions are listed at the end of ...

Overview of the Fundamental Reactions and Degradation Mechanisms of NOx Storage/Reduction Catalysts

This paper surveys the present status and the perspective of de-NO x SCR catalysis for stationary sources, that is based on the reduction of NO x by NH 3 to form water and nitrogen. After a brief description of the SCR chemistry the characteristics of commercial SCR catalysts, their physico-chemical properties and reactivity, and their performances in both NO x reduction and SO 2 oxidation are presented. The mechanism of the SCR reactions, the mathematical modeling of the reactor and the arrangements of the reactor and process are then described. Finally the emerging technologies for NO x removal and the future perspectives of the SCR catalysis are outlined.

Kouichi Kasahara

Papers

The new concept 3-way catalyst for automotive lean-burn engine: NOx storage and reduction catalyst

Development of New Concept Three-Way Catalyst for Automotive Lean-Burn Engines