Catalyst Engineering Technology

Fundamentals and Applications

Jean W. L. Beeckman

• Publisher: Wiley
• Year: 2020
• Print ISBN: 9781119634942
• eBook ISBN: 9781119635017
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Industrial & Technical Chemistry

This book gives a comprehensive explanation of what governs the breakage of extruded materials, and what techniques are used to measure it. The breakage during impact aka collision is explained using basic laws of nature allowing readers to determine the handling severity of catalyst manufacturing equipment and the severity of entire plants. This information can then be used to improve on the architecture of existing plants and how to design grass-roots plants. The book begins with a summary of particle forming techniques in the particle technology industry. It covers extrusion technology in more detail since extrusion is one of the workhorses for particle manufacture. A section is also dedicated on how to describe transport and chemical reaction in such particulates for of course their final use. It presents the fundamentals of the study of breakage by relating basic laws in different fields (mechanics and physics) and this leads to two novel dimensionless groups that govern breakage. These topics are then apply these topics to R&D scale-up and manufacturing and shows how this approach is directly applicable.

1
Catalyst Preparation Techniques and Equipment

1.1 Introduction

A catalyst is made up of its constituent components that are one or more active phases held together with one or more binder components. The components of a catalyst are initially in the form of loose powders. The forming of a catalyst entails using powders that serve as building blocks and making the catalyst hold together as a shaped particle. Excellent textbooks by Stiles [1] and Le Page [2] cover catalyst formation and show the typical equipment, methods, and materials used commercially. Adding catalytic components inside a particle by impregnation or by ion exchange with solutions of metals followed by using appropriate drying and calcination procedures makes catalysts useful for many processes.

The science and experience of impregnation, drying, and calcination is a vast area of knowledge represented by many excellent papers. Cited here, among a wealth of research on the subject, will be works by Neimark et al. [3], Chester and Derouane [4], Marceau et al. [5], Lekhal et al. [6, 7], and de Jong [8]. The Rutgers Catalyst Consortium headed by Professor Benjamin Glasser has been investigating manufacturing fundamentals for the last two decades. Many of their published contributions yield a solid basis for applied methods and numerical models for the many facets of catalyst manufacturing.

In the area of catalyst impregnation, I will cite Chester et al. [9], Chester and Muzzio [10], Liu et al. [11], Shen et al. [12], Romanski et al. [13–15], and Koynov et al. [16]. On the subject of metal profiles in catalyst particles, I will mention Kresge et al. [17] and Liu et al. [18–20]. For rotary calcination, I will mention Chaudhuri et al. [21, 22], Gao et al. [23], Paredes et al. [24], Emady et al. [25], and Yohannes et al. [26, 27]. Last but not least, this book cites a very interesting historical perspective of the many pioneers in heterogeneous catalysis by Davis and Hettinger [28].

The common structural properties of interest for catalysts include surface area, porosity, pore size distribution, particle shape, and particle size. A wonderful textbook in this area is by Thomas and Thomas [29].

Part of the catalyst‐forming technology includes the development of the mechanical strength of the catalyst. This aspect is sometimes overlooked initially, but should not be underestimated or forgotten and taken for granted. Insufficient mechanical strength requires the changing or adjusting of recipes in order to yield the strength needed for handling and subsequent use. Changing recipes at the end of the game always brings the risk of an unforeseen detrimental impact on catalyst activity.

Catalysts come in many shapes, and the processes that allow their manufacture include extrusion, spray drying, bead forming by dripping, bead forming in granulation pans, fluid bed granulation, spheronization, and pelletizing. The process of use in the chemical and petrochemical industries dictates the size and the shape of the catalyst, while the manufacturing cost often dictates the choice of the catalyst‐forming process. Extrusion and spray drying, Masters [30], yield economic manufacturing solutions when large quantities of catalyst are required, such as in the petrochemical industry.

In the automotive industry, monolith‐type extruded catalysts are well established for their low pressure drop and hydrothermal stability properties. Monolith manufacturing processes have been described in the open literature and are available in textbooks, including those of Cybulski and Moulijn [31] and Satterfield [32].

Beyond the forming of a catalyst particle, many more operations are required to make a final catalyst. For instance, after the forming, drying followed by calcination at high temperatures set the matrix of a catalyst and yield the basic strength properties of the catalyst. Thereafter, the catalyst may require metal components to be introduced into its structure, followed by drying and calcination.

Catalytic metal impregnation, drying, and calcination can lead to further breakage of catalyst extrudates and a loss of catalyst and catalyst quality. Bringing an optimal recipe to fruition may require sacrificing many thousands of pounds of material together with precious plant manufacturing time.

Catalyst manufacturing plants are built with a combination of different pieces of production equipment in mind. The layout and the design of the production path needs to allow for product quality assurance and product quality control. Usually, new plants are designed based on experience with existing plants, but there is little guidance from first‐principles methods based on the science of the phenomenon of breakage by collision or by stress in a fixed bed of catalyst. Often, a reference catalyst is tested in a piece of equipment and the decision to go ahead with that equipment or to change it depends on the outcome of that test. Engineers and chemists with many years of experience in the catalyst manufacturing industry are valuable resources when it comes to designing new plants or modifying existing ones.

1.1.1 What are Catalysts?

Catalysts are solid bodies with a porous structure that allows for the fantastic ingress of reagents and egress of products. This accessibility exposes the bulk fluid to enormous surface areas and densities of the catalytic sites located inside these catalytic bodies. Maximizing surface area and accessibility is always one of the goals,...

Table of contents

• Cover
• Table of Contents
• About the Author
• Acknowledgments - Dankwoord
• Foreword
• 1 Catalyst Preparation Techniques and Equipment
• 2 Extrusion Technology
• 3 The Aspect Ratio of an Extruded Catalyst
• 4 Steady‐state Diffusion and First‐order Reaction in Catalyst Networks
• Index
• End User License Agreement