Mechanisms of catalyst deactivation
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.
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TL;DR: In this paper, the authors compared the available electrolysis and methanation technologies with respect to the stringent requirements of the power-to-gas (PtG) chain such as low CAPEX, high efficiency, and high flexibility.
1,841 citations
Cites background from "Mechanisms of catalyst deactivation..."
...This strong temperature variation can lead to catalyst cracking or sintering which diminishes the catalyst lifetime [67]....
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...The main concerns for the catalyst are possible cracking or sintering [67]....
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...Contrastingly, sulphur and sulphur-containing components are a known catalyst poison for the nickel catalysts used in catalytic methanation [67,122]....
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...However, nickel based catalysts require a high purity of the feed gas (with respect to halogeneous and sulphurous compounds, among others) [66,67]....
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...As a consequence, the catalyst is eventually deactivated [67]....
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TL;DR: The motivation to develop CO2-based chemistry does not depend primarily on the absolute amount of CO2 emissions that can be remediated by a single technology and is stimulated by the significance of the relative improvement in carbon balance and other critical factors defining the environmental impact of chemical production in all relevant sectors in accord with the principles of green chemistry.
Abstract: CO2 conversion covers a wide range of possible application areas from fuels to bulk and commodity chemicals and even to specialty products with biological activity such as pharmaceuticals. In the present review, we discuss selected examples in these areas in a combined analysis of the state-of-the-art of synthetic methodologies and processes with their life cycle assessment. Thereby, we attempted to assess the potential to reduce the environmental footprint in these application fields relative to the current petrochemical value chain. This analysis and discussion differs significantly from a viewpoint on CO2 utilization as a measure for global CO2 mitigation. Whereas the latter focuses on reducing the end-of-pipe problem “CO2 emissions” from todays’ industries, the approach taken here tries to identify opportunities by exploiting a novel feedstock that avoids the utilization of fossil resource in transition toward more sustainable future production. Thus, the motivation to develop CO2-based chemistry does...
1,346 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
TL;DR: In this paper, the authors provide a comprehensive review with respect to the structure, chemistry, design and selection of materials, underlying mechanisms, and performance of each SOFC component, and it opens up the future directions towards pursuing SOFC research.
1,119 citations
TL;DR: This Review systematically documents the progresses and developments made in the understanding and design of heterogeneous catalysts for VOC oxidation over the past two decades and addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions.
Abstract: It is well known that urbanization and industrialization have resulted in the rapidly increasing emissions of volatile organic compounds (VOCs), which are a major contributor to the formation of secondary pollutants (e.g., tropospheric ozone, PAN (peroxyacetyl nitrate), and secondary organic aerosols) and photochemical smog. The emission of these pollutants has led to a large decline in air quality in numerous regions around the world, which has ultimately led to concerns regarding their impact on human health and general well-being. Catalytic oxidation is regarded as one of the most promising strategies for VOC removal from industrial waste streams. This Review systematically documents the progresses and developments made in the understanding and design of heterogeneous catalysts for VOC oxidation over the past two decades. It addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions. It also highlights the primary routes for catalyst deactivation and discusses protocols for their subsequent reactivation. Kinetic models and proposed oxidation mechanisms for representative VOCs are also provided. Typical catalytic reactors and oxidizers for industrial VOC destruction are further discussed. We believe that this Review will provide a great foundation and reference point for future design and development in this field.
1,074 citations
References
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Book•
01 Jan 1985
TL;DR: In this paper, the International System of Units (SI) is used to measure the properties of materials and their properties in the context of materials science and engineering, including properties of metal alloys.
Abstract: List of Symbols.Introduction.Atomic Structure and Interatomic Bonding.The Structure of Crystalline Solids.Imperfections in Solids.Diffusion.Mechanical Properties of Metals.Dislocations and Strengthening Mechanisms.Failure.Phase Diagrams.Phase Transformations in Metals: Development of Microstructure and Alteration of Mechanical Properties.Thermal Processing of Metal Alloys.Metals Alloys.Structures and Properties of Ceramics.Applications and Processing of Ceramics.Polymer Structures.Characteristics, Applications, and Processing of Polymers.Composites.Corrosion and Degradation of Materials.Electrical Properties.Thermal Properties.Magnetic Properties.Optical Properties.Materials Selection and Design Considerations.Economic, Environmental, and Societal Issues in Materials Science and Engineering.Appendix A: The International System of Units (SI).Appendix B: Properties of Selected Engineering Materials.Appendix C: Costs and Relative Costs for Selected Engineering Materials.Appendix D: Mer Structures for Common Polymers.Appendix E: Glass Transition and Melting Temperatues for Common Polymeric Materials.Glossary.Answers to Selected Problems.Index.
6,674 citations
Book•
30 Nov 2001
TL;DR: Catalysis - introduction and fundamentals catalytic phenomena catalyst materials, properties and preparation catalyst characterization and selection reactors, reactor design, and activity testing catalyst deactivation - causes, mechanisms and treatment hydrogen production and synthesis gas reactions hydrogenation and dehydrogenation of organic compounds oxidation of inorganic and organic compounds petroleum refining and processing environmental catalysis - stationary sources homogenous catalysis, enzyme catalysis and polymerization catalysis as mentioned in this paper.
Abstract: Catalysis - introduction and fundamentals catalytic phenomena catalyst materials, properties and preparation catalyst characterization and selection reactors, reactor design, and activity testing catalyst deactivation - causes, mechanisms and treatment hydrogen production and synthesis gas reactions hydrogenation and dehydrogenation of organic compounds oxidation of inorganic and organic compounds petroleum refining and processing environmental catalysis - stationary sources homogenous catalysis, enzyme catalysis, and polymerization catalysis.
982 citations
TL;DR: Insight into the structure of surface alloys combined with an understanding of the relation between the surface composition and reactivity is shown to lead directly to new ideas for catalyst design.
Abstract: Detailed studies of elementary chemical processes on well-characterized single crystal surfaces have contributed substantially to the understanding of heterogeneous catalysis. Insight into the structure of surface alloys combined with an understanding of the relation between the surface composition and reactivity is shown to lead directly to new ideas for catalyst design. The feasibility of such an approach is illustrated by the synthesis, characterization, and tests of a high-surface area gold-nickel catalyst for steam reforming.
933 citations