Catalysis has made a rapid progress and there can be observed many new applications of catalysts. Heterogeneous and homogeneous catalysts used commercially are chemically and physically complex, sophisticated materials and because of the chemical and physical complexity of catalysts, catalyst research and development is highly multidisciplinary field which require knowledge of chemistry, chemical engineering, material science and physics. In order to design, develop and prepare new catalysts, a process which requires detailed knowledge of catalyst material, catalyst properties and art/science of catalyst preparation. The main objective of this book is to present an overview on catalyst materials and properties so that both the student and the experienced practitioner can understand the concept of catalyst materials and properties.
Table of Contents
1. Introduction
1.1 Catalyst Performance
2. Catalyst materials
2.1 Makeup of a typical heterogeneous catalyst
2.2 Active catalytic phases
2.2.1 Selecting the active catalysts
2.3 Carriers (Supports)
2.3.1 Alumina
2.3.2 Silicas
2.3.3 Carbons
2.3.4 Titania
2.3.5 Synthesis of zeolites and mesoporous materials
2.3.6 Other supports
2.3.6.1 Monolith Support
2.3.7 Selecting the right support
2.4 Promoters
2.5 Inhibitors
3. Catalyst Properties
3.1 Introduction
3.2 Physical, mechanical and chemical properties
3.2.1 Physical and mechanical properties, their definition and their Importance
3.2.2 Chemical Properties
3.2.3 Dynamic properties
3.3 Catalyst characterization
4. References
Book Objective and Key Topics
The primary objective of this book is to provide a comprehensive overview of catalyst materials and their inherent properties to help students and experienced practitioners understand the multidisciplinary field of catalysis, ranging from chemical design to industrial application.
- Fundamentals of heterogeneous and homogeneous catalyst components.
- Technical requirements for industrial catalysts including activity, selectivity, and stability.
- Detailed breakdown of catalyst supports (carriers), promoters, and inhibitors.
- Analysis of physical, mechanical, chemical, and dynamic catalyst properties.
- In-depth examination of monolithic catalysts, their structures, and industrial production methods.
Excerpt from the Book
2.3 Carriers (Supports)
The surface interactions hold the key to the catalyst’s activity, selectivity and stability. Unlike the situation for molecular catalysts, the bulk parameters such as particle size, shape and mechanical strength are crucial here. Particle size is directly related to the accessible active surface area. Platinum, for example, is an excellent catalyst for alkane dehydrogenation but it is also very expensive (ca. €32/g or $44/g in February, 2007). Suppose you use a cubic centimeter of Pt as your catalyst. This cube would weigh 21.3 g and cost about €700 ($1000). The available surface area of such a cube would be only 5 cm2 because one side would have to be attached to the reactor. Now, if you break this cube into 1012 smaller cubes, each of which has 1 mm sides, the total available surface area would be 5 · 1012 mm2 or 50 000 cm2.
State of the art catalyst synthesis methods can produce particles as small as 2 nm with correspondingly huge surface areas. Interestingly, reducing the particle size can also cause undesired effects, due to surface penetration by foreign atoms. One reason why Pt is an excellent oxidation catalyst is that O2 is readily adsorbed on Pt particles, dissociating to two O atoms which react with a variety of substrates. When the particles are very small (<10 nm), they react with oxygen and form platinum oxide. The resulting strong Pt-O bond lowers the catalytic activity, despite the large metal surface area.
Placing all these small particles in one reactor at high temperatures would cause very high back-pressures and agglomeration. This can be avoided by coating the active metal particles on a (porous) support with a high surface area e.g., silica, alumina, zeolites, or carbon. The shape and mechanical strength of the catalyst particles are also important especially in large scale applications (refinery reactors can be 20 m high, holding as much as 50 tons of catalyst). They determine the packing in the reactor and ultimately the flow of the gaseous reactants and products to and from the catalyst [5].
Summary of Chapters
1. Introduction: Introduces the multidisciplinary nature of catalysis and defines the essential performance factors for industrial catalysts.
2. Catalyst materials: Details the composition of heterogeneous catalysts, including active phases, various support materials, promoters, and inhibitors.
3. Catalyst Properties: Discusses the classification and categorization of catalysts based on their physical, mechanical, chemical, and dynamic characteristics.
4. References: Provides a comprehensive list of scientific literature and sources utilized for the book's content.
Keywords
Catalysis, Heterogeneous catalysts, Catalyst supports, Alumina, Silica, Monoliths, Catalyst activity, Catalyst selectivity, Catalyst stability, Promoters, Inhibitors, Surface area, Porosity, Chemical properties, Catalyst characterization
Frequently Asked Questions
What is the primary focus of this book?
This book focuses on the fundamental concepts, materials, and properties that define industrial catalysts, specifically emphasizing the role of supports and the design of catalytic systems.
What are the central themes of the work?
The central themes include the structural makeup of heterogeneous catalysts, the selection of appropriate support materials, the impact of promoters/inhibitors, and the optimization of physical and chemical properties.
What is the main objective of this book?
The main objective is to provide an overview of catalyst materials and their properties so that both students and experienced practitioners can effectively design, develop, and prepare new catalysts.
Which scientific methodologies are covered?
The book covers material synthesis routes (sol-gel, precipitation), characterization methods (NMR, chemisorption), and principles of catalyst engineering, such as the triangular concept for catalyst design.
What is discussed in the main part of the book?
The main part covers the specific functions of catalyst supports, an exhaustive categorization of carrier materials, the complex mechanisms of promoters and inhibitors, and a deep dive into the properties of monolithic catalyst structures.
What key terms characterize the work?
The work is characterized by terms such as active phases, monolithic catalysts, surface area, sintering, SMSI effect, and structural vs. textural promoters.
How does alumina function as a catalyst support?
Alumina serves as a support due to its thermal and mechanical stability, providing a high surface area for active components and contributing its own acidic properties in specific catalytic reactions.
What are monolithic catalysts and why are they important?
Monolithic catalysts are structured catalyst shapes with straight parallel channels, crucial in environmental applications like automotive catalytic converters because they offer low pressure drops and excellent mass transfer.
What is the significance of the SMSI effect?
The Strong Metal-Support Interaction (SMSI) effect is a phenomenon that explains changes in chemisorption and activity in catalysts (e.g., Pt on TiO2), which can be exploited to influence product selectivity.
How does the book address catalyst deactivation?
The book discusses various causes of deactivation, such as coking, sintering, and poisoning, and highlights how to mitigate these issues through proper choice of supports and promoters.
- Quote paper
- Femina Patel (Author), 2014, Catalyst materials & properties, Munich, GRIN Verlag, https://www.grin.com/document/275585
