Further Analysis of the Effect of Oxygen Concentration on the Thermal Aging of Automotive Catalysts
28 Mar 2017-
About: The article was published on 2017-03-28. It has received None citations till now. The article focuses on the topics: Limiting oxygen concentration.
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TL;DR: The literature treating mechanisms of catalyst deactivation is reviewed in this paper, which can be classified into six distinct types: (i) poisoning, (ii) fouling, (iii) thermal degradation, (iv) vapor compound formation accompanied by transport, (v) vapor solid and/or solid solid reactions, and (vi) attrition/crushing.
Abstract: The literature treating mechanisms of catalyst deactivation is reviewed. Intrinsic mechanisms of catalyst deactivation are many; nevertheless, they can be classified into six distinct types: (i) poisoning, (ii) fouling, (iii) thermal degradation, (iv) vapor compound formation accompanied by transport, (v) vapor-solid and/or solid-solid reactions, and (vi) attrition/crushing. As (i), (iv), and (v) are chemical in nature and (ii) and (v) are mechanical, the causes of deactivation are basically three-fold: chemical, mechanical and thermal. Each of these six mechanisms is defined and its features are illustrated by data and examples from the literature. The status of knowledge and needs for further work are also summarized for each type of deactivation mechanism. The development during the past two decades of more sophisticated surface spectroscopies and powerful computer technologies provides opportunities for obtaining substantially better understanding of deactivation mechanisms and building this understanding into comprehensive mathematical models that will enable more effective design and optimization of processes involving deactivating catalysts. © 2001 Elsevier Science B.V. All rights reserved.
2,526 citations
TL;DR: In this article, a review on deactivation and regeneration of heterogeneous catalysts classifies deactivation by type (chemical, thermal, and mechanical) and by mechanism (poisoning, fouling, thermal degradation, vapor formation, vapor-solid and solid-solid reactions, and attrition/crushing).
Abstract: Deactivation of heterogeneous catalysts is a ubiquitous problem that causes loss of catalytic rate with time. This review on deactivation and regeneration of heterogeneous catalysts classifies deactivation by type (chemical, thermal, and mechanical) and by mechanism (poisoning, fouling, thermal degradation, vapor formation, vapor-solid and solid-solid reactions, and attrition/crushing). The key features and considerations for each of these deactivation types is reviewed in detail with reference to the latest literature reports in these areas. Two case studies on the deactivation mechanisms of catalysts used for cobalt Fischer-Tropsch and selective catalytic reduction are considered to provide additional depth in the topics of sintering, coking, poisoning, and fouling. Regeneration considerations and options are also briefly discussed for each deactivation mechanism.
1,173 citations
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01 Oct 1994
TL;DR: In this paper, the authors present an overview of the history of catalytic components in diesel engines and their application in a variety of applications, such as catalytic converter, catalytic converters, and catalytic monoliths.
Abstract: Preface. ACKNOWLEDGEMENTS. ACKNOWLEDGEMENTS, FIRST EDITION. ACKNOWLEDGEMENTS, SECOND EDITION. I. FUNDAMENTALS. 1. Catalyst Fundamentals. 1.1 Introduction. 1.2 Catalyzed Verses Non-Catalyzed Reactions. 1.3 Catalytic Components. 1.4 Selectivity. 1.5 Promoters and their Effect on Activity and Selectivity. 1.6 Dispersed Model for Catalytic Component on Carrier: Pt on Al 2 O 3 . 1.7 Chemical and Physical Steps in Heterogeneous Catalysis. 1.8 Practical Significance of knowing the Rate-Limiting Step. 2. The Preparation of Catalytic Materials: Carriers, Active Components, and Monolithic Substrates. 2.1 Introduction. 2.2 Carriers. 2.3 Making the Finished Catalyst. 2.4 Nomenclature for Dispersed Catalysts. 2.5 Monolithic Materials as Catalyst Substrates. 2.6 Preparing Monolithic Catalysts. 2.7 Catalytic Monoliths. 2.8 Catalyzed Monoliths Nomenclature. 2.9 Precious Metal Recovery from Monolithic Catalysts. 3. Catalyst Characterization. 3.1 Introduction. 3.2 Physical Properties of Catalysts. 3.3 Chemical and Physical Morphology Structures of Catalytic Materials . 3.4 Techniques for Fundamental Studies. 4. Monolithic Reactors for Environmental Catalysis. 4.1 Introduction. 4.2 Chemical Kinetic Control. 4.3 The Arrhenius Equation and Reaction Parameters. 4.4 Bulk Mass Transfer. 4.5 Reactor Bed Pressure Drop. 4.6 Summary. 5. Catalyst Deactivation. 5.1 Introduction. 5.2 Thermally Induced Deactivation. 5.3 Poisoning. 5.4 Washcoat Loss. 5.5 General Comments on Deactivation Diagnostics in Monolithic Catalysts for Environmental Applications. II. MOBILE SOURCE. 6. Automotive Catalyst. 6.1 Emissions and Regulations. 6.2 The Catalytic Reactions for Pollution Abatement. 6.3 The Physical Structure of the Catalytic Converter. 6.4 First-Generation Converters: Oxidation Catalyst (1976-1979). 6.5 NOx, CO and HC Reduction: The Second Generation: The Three Way Catalyst (1979 - 1986). 6.6 Vehicle Test Procedures (U.S., European and Japanese). 6.7 NOx, CO and HC Reduction: The Third Generation (1986 - 1992). 6.8 Palladium TWC Catalyst: The Fourth Generation (Mid-1990s). 6.9 Low Emission Catalyst Technologies. 6.10 Modern TWC Technologies for the 2000s. 6.11 Towards a Zero-Emission Stoichiometric Spark-Ignit Vehicle. 6.12 Engineered Catalyst Design. 6.13 Lean-Burn Spark-Ignited Gasoline Engines. 7. Automotive Substrates. 7.1 Introduction to Ceramic Substrates. 7.2 Requirements for Substrates. 7.3 Design Sizing of Substrates. 7.4 Physical Properties of Substrates. 7.5 Physical Durability. 7.6 Advances in Substrates. 7.7 Commercial Applications. 7.8 Summary. 8. Diesel Engine Emissions. 8.1 Introduction. 8.2 Worldwide Diesel Emission Standards. 8.3 NO x -Particulate Tradeoff. 8.4 Analytical Procedures for Particulates. 8.5 Particulate Removal. 8.6 NOX Reduction Technologies. 8.7 2007 Commercial System Designs (PM Removal Only). 8.8 2010 Commercial System Approaches under Development (PM and NO x Removal). 8.9 Retrofit and Off-Highway. 8.10 Natural Gas Engines. 9. Diesel Catalyst Supports and Particulate Filters. 9.1 Introduction. 9.2 Health Effects of Diesel Particulate Emissions. 9.3 Diesel Oxidation Catalyst Supports. 9.4 Design/Sizing of Diesel Particulate Filter. 9.5 Regeneration Techniques. 9.6 Physical Properties and Durability. 9.7 Advances in Diesel Filters. 9.8 Applications. 9.9 Summary. 10. Ozone Abatement within Jet Aircraft. 10.1 Introduction. 10.2 Ozone Abatement. 10.3 Deactivation. 10.4 Analysis of In-Flight Samples. 10.5 New Technology. III. STATIONARY SOURCES. 11. Volatile Organic Compounds . 11.1 Introduction. 11.2 Catalytic Incineration. 11.3 Halogenated Hydrocarbons. 11.4 Food Processing. 11.5 Wood Stoves. 11.6 Process Design. 11.7 Deactivation. 11.8 Regeneration of Deactivated Catalysts. 12. Reduction of NO x . 12.1 Introduction. 12.2 Nonselective Catalytic Reduction of NOx. 12.3 Selective Catalytic Reduction of NOx. 12.4 Commercial Experience. 12.5 Nitrous Oxide (N 2 O). 12.6 Catalytically Supported Thermal Combustion. 13. Carbon Monoxide and Hydrocarbon Abatement from Gas Turbines. 13.1 Introduction. 13.2 Catalyst for CO Abatement. 13.3 Non-Methane Hydrocarbon (NMHC) Removal. 13.4 Oxidation of Reactive Hydrocarbons. 13.5 Oxidation of Unreactive Light Paraffins. 13.6 Catalyst Deactivation. 14. Small Engines. 14.1 Introduction. 14.2 Emissions. 14.3 EPA Regulations. 14.4 Catalyst for Handheld and Nonhandheld Engines. 14.5 Catalyst Durability. IV. NEW AND EMERGING TECHNOLOGIES. 15. Ambient Air Cleanup. 15.1 Introduction. 15.2 Premair (R) Catalyst Systems. 15.3 Other Approaches. 16. Fuel Cells and Hydrogen Generation. 16.1 Introduction. 16.2 Low-Temperature PEM Fuel Cell Technology. 16.3 The Ideal Hydrogen Economy. 16.4 Conventional Hydrogen Generation. 16.5 Hydrogen Generation from Natural Gas for PEM Fuel Cells. 16.6 Other Fuel Cell Systems. INDEX.
619 citations
TL;DR: In this article, both fresh and accelerated aging of TWC catalysts were tested for activity as TWC, both fresh [G.C. Koltsakis, and A.M. Stamatelos, Progr. Energy Combust. Sci. 23 (1997) 1] and after accelerated aging.
95 citations