Catalyst Engineering Technology Fundamentals and Applications

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.

Jean Beeckman obtained his chemical engineering degree and Doctorate at the University of Ghent, Belgium in 1979. Since 2001 has been with ExxonMobil in Annandale, NJ. His entire career has been in the area of catalyst development, catalyst manufacturing and mathematical modeling. Jean has over 35 patents and over 25 peer reviewed technical publications.

Acknowledgement

Foreword

Table of Contents

Chapter I: Catalyst Preparation Techniques and Equipment

1.1 Introduction

1.1.2 What Are Catalysts

1.1.3 Catalyst Composition

1.2 Forming of Catalysts

1.2.1 Catalysts Formed By Extrusion

1.2.1.1. Typical Materials

1.2.1.2 Mixing, Mulling, Granulation and Kneading

1.2.1.3 Extrusion

1.2.1.4 Extrusion Efficiency

1.2.2 Spheroidal Catalysts

1.2.2.1 Spray Drying

1.2.2.2 Bead dripping

1.2.2.3 Granulation Pans

1.2.2.4 Fluid Bed Granulation

1.2.2.5 Spheronization

1.2.3 Catalysts Formed By Pelletizing

1.2.4 Monolith Type Catalysts

1.3 Impregnation and Drying

1.4 Rotary Calcination

1.4.1 Introduction

1.4.2 Residence Time In A Rotary Calciner Without A Dam

1.4.3 Residence Time In A Rotary Calciner With A Dam

1.4.4 Residence Time Distribution In A Rotary Calciner

1.5 From the Laboratory to a Commercial Plant

1.5.1 Scale-Up Technology

1.5.2 Scale-Down Technology

Nomenclature for Chapter I

References for Chapter I

Chapter II: Extrusion Technology

2.1 Background

2.2 Rheology

2.2.1 Shear Stress, Wall Shear Stress and Shear Rate

2.2.2 Friction

2.2.3 Rheometer Data

2.2.4 Comparing Friction and Wall Shear Stress

2.2.5 A Paste under Stress

2.2.6 The Yield Strength of a Paste

2.2.7 Paste Density

2.3 Extrusion

2.3.1 Ram Extrusion

2.3.2 Auger Extrusion

2.3.2.1 Die Equation or Die Characteristic

2.3.2.2 Model 1: The Extruder Characteristic Equation

2.3.2.2.1 Geometric Paste Flow

2.3.2.2.2 Back Flow Caused by Restriction at the Die

2.3.2.2.3 Extruder Operating Point

2.3.2.3 Model 2: Pressure Profile along the Auger and the Die

2.3.2.4 Model 3: Friction Based Models

2.3.2.4.1 General Background

2.3.2.4.2 The Euler-Eytelwein Equation or Capstan Equation

2.3.2.5 Pictorial for Paste Movement against a Blind Die

2.3.2.6 Pictorial for Paste Movement against an Open Die

Nomenclature for Chapter II

References for Chapter II

Chapter III: The Aspect Ratio of an Extruded Catalyst; An In-Depth Study

3.1 General

3.2 Introduction to Catalyst Strength and Catalyst Breakage

3.3 Mechanical Strength of Catalysts

3.3.1 Bending Strength of Extrudates

3.3.2 Extrudate Side Crush Strength

3.3.3 Extrudate Bulk crush Strength

3.3.4 Crush Strength of a Sphere

3.3.5 Young’s Modulus of Elasticity

3.4 Experimental Measurement of the Mechanical Strength

3.4.1 Bending Strength aka Modulus Of Rupture (MOR) Instrument

3.4.1.1 Strain Rate Sensitivity

3.4.1.2 Bridge Width Sensitivity

3.4.1.3 Influence of the Length of the Extrudate

3.4.1.4 MOR Reproducibility

3.4.1.5 Wet MOR

3.4.1.6 MOR Report

3.4.2 Side Crush Strength, Bead Crush Strength and Bulk Crush Strength

3.4.3 A Speculation of the Variability of Strength from Extrudate to Extrudate

3.5 Breakage By Collision

3.5.1 Background

3.5.2 Mathematical Modeling Of Extrudate Breakage

3.5.2.1 Experimental

3.5.2.2 Modeling via a 1st Order Padé’ Approximation

3.5.2.2.1 Two Fundamental Parameters

3.5.2.2.2 General Two-parameter Model Fitting

3.5.2.2.3 Ideal Materials

3.5.2.2.4 Physical Arguments Supporting Ideal Materials

3.5.2.2.5 The Cumulative Break Function

3.5.2.2.6 Golden Ratio Materials

3.5.2.2.7 A 2nd Order Break Law for Collision

3.5.2.3 Application To Operational Severity

3.5.2.3.1 Optimal Sequencing of Drops with Different Severity

3.5.2.3.2 Managing the Severity of a Drop

3.5.3 Fundamentals of Breakage by Collision

3.5.3.1 Modulus of Rupture

3.5.3.2 Impact Force From Newton’s 2nd Law

3.5.3.2.1 Elastic Collision without Breakage

3.5.3.2.2 Collision with Breakage

3.5.3.2.3 Impact Velocity and Terminal Velocity

3.5.3.2.4 Duration of the Contact Time in Collisions

3.5.3.3 Force Diagram at Twice the Asymptotic Aspect Ratio

3.5.3.3.1 A Dimensionless Group for Breakage by Collision

3.5.3.3.2 Development of the Severity Functional of a Collision

3.5.3.3.3 Learnings From

3.5.3.3.4 Worked Example: Catalysts in Space

3.5.3.4 Concluding Remarks on Be

3.6 Breakage By Stress in a Fixed Bed

3.6.1 Experimental

3.6.2 Theoretical

3.6.2.1 Areal Densities of Catalyst Extrudates

3.6.2.2 Balance of the Rupture Force with a Fixed Bed Static Load

3.6.2.2.1 Catalyst Breakage Due to the Weight of a Shallow Catalyst Bed

3.6.2.2.2 Catalyst Breakage Due to the Weight of a Deep Catalyst Bed

3.6.2.3 Formation of Fines during Catalyst Breakage.

3.6.2.4 A Consideration on Break Energy

3.6.2.5 Simulation of Fixed Bed Breakage via the Bulk Crush Strength Test

3.7 Breakage in Contiguous Equipment

3.7.1 Breakage from an Extrusion line

3.7.1.1 Severity Functional For A Single Piece Of Equipment

3.7.1.2 Severity Derivation For Contiguous Equipment

3.7.1.3 Application To A Commercial Plant

3.7.2 Breakage With a Variable Input Aspect Ratio

3.7.2.1 Theoretical

3.7.2.2 Experimental

3.7.2.2.1 Aspect Ratio Comparison Between the Support and the Final Catalyst

3.7.2.2.2 Bending Strength Comparison of Catalyst and Support

3.8 Statistical Methods Applied to Manufacturing Materials

3.8.1 Dry Mixing of Powders

3.8.2 Expected Values of a New Batch Compared to Historical Values

Nomenclature for Chapter III

Greek Symbols for Chapter III

Subscripts for Chapter III

References for Chapter III

Chapter IV: Steady State Diffusion and First Order Reaction in Catalyst Networks

4.1 Introduction

4.2 Classic Continuum Approach

4.3 The Network Approach

4.3.1 Mass Transfer between Nodes

4.3.2 First Order Reaction in a Node

4.3.3 Regular Networks

4.3.3.1 Introduction

4.3.3.2 A One Dimensional Network, a String of Nodes

4.3.3.3 Two Dimensional Networks with Square Connectivity

4.3.3.3.1 A Rectangular Network Open on All Sides

4.3.3.3.2 A Network Open on Opposing Sides Only

4.3.3.3.3 A Network Open on One Side Only

4.3.3.3.4 Semi-infinite Networks

4.3.3.4 Three Dimensional Regular Networks

4.3.3.4.1 Rectangular Parallelepiped

4.3.3.4.2 The Catalytic Box

4.3.3.4.3 Semi-infinite 3-D Space

4.3.3.5 Worked Example: p-Xylene Selectivity Boost

4.3.3.5.1 Generalities

4.3.3.5.2 Numerical Solution

4.3.3.5.3 An Analytical Solution

4.3.3.5.4 Selectivity for a Network Open on One Side

4.3.3.5.5 Selectivity for a Network Accessible via a Single Opening

4.3.4 Irregular Networks

4.3.4.1 Generalities

4.3.4.2 A Corollary

4.3.4.3 Diffusion in an Arbitrary Network

4.3.4.3.1 The Material Balance Matrix for Diffusion

4.3.4.3.2 General Solution

4.3.4.3.3 An Alternate Solution Method for Diffusion

4.3.4.3.4 On the Structure of the Matrix

4.3.4.3.5 The Complementary Situation

4.3.4.3.6 The Meaning of

4.3.4.3.6.1 Worked Example for a Diffusional Point Source Calculation in a Discrete Network

4.3.4.3.7 Diffusion from a Point Source in the Network

4.3.4.3.8 Diffusion from a Point Source along Classic Lines

4.3.4.3.9 Merging the Network Approach and the Classic Approach

4.3.4.3.10 A Property of the Diffusion Matrix

4.3.4.3.10.1 Worked Example

4.3.4.4 Diffusion and First Order Reaction in an Arbitrary Network

4.3.4.4.1 The Material Balance Matrix for Reaction and Diffusion

4.3.4.4.2 General Solution for Reaction and Diffusion

4.3.4.4.3 The Bosanquet Average Reaction-Diffusion Matrix

4.3.4.4.4 The Meaning of

4.3.4.4.4.1 An Example Calculation of Reaction and Diffusion

4.3.4.4.4.2 An Example Calculation for a Perturbation in a Small Network

4.3.4.4.5 Diffusion and Reaction from a Point Source along Classic Lines

4.3.4.4.6 A “Black Body” Catalyst: a Closed Sphere with a Pinhole Access Leading to the Center

4.3.4.4.7 Alternate Solution Method

4.3.4.4.8 Network Perimeter Blocking

4.3.4.4.9 Considering Surface and Sub-surface Nodes

4.3.4.4.10 Non-first Order Reaction

4.3.5 Treatise of Very Deep Networks

4.3.5.1 Random Variables

4.3.5.1.1 The Distribution of Random Variables

4.3.5.2 Convergence for the Network Approach

4.3.5.3 Diffusion in Deep Networks

4.3.5.3.1 Diffusion along a Deep String of Nodes

4.3.5.3.2 Diffusion in a Deep Slab

4.3.5.3.3 The Equivalent Network Efficacy

4.3.5.4 First Order Reaction and Diffusion in Very Deep Networks

4.3.5.4.1 The Minimum Eigenvalue of

4.3.5.4.1.1 Worked Example

4.3.5.4.2 Perturbation in a VDN Case

4.3.5.4.3 More on the Local Average of Node Properties

4.3.5.4.4 Diffusion and First Order Reaction in a Network of Interconnected Parallel Strings

4.3.5.4.5 Taking More Advantage of VDNP and the Classic Continuum Approach Equivalence

4.3.5.4.6 A Concise Formulation for Based on in the Case of VDNP

4.3.5.4.7 Summary and Conclusion

Nomenclature for Chapter IV

Greek Symbols for Chapter IV

Appendix Captions for chapter IV

References for Chapter IV

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