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Microstructured Devices for Chemical Processing

Microstructured Devices for Chemical Processing

Madhvanand N. Kashid, Albert Renken, Lioubov Kiwi-Minsker

ISBN: 978-3-527-68518-9

Sep 2014

384 pages

$120.99

Description

Faster, cheaper and environmentally friendly, these are the criteria for designing new reactions and this is the challenge faced by many chemical engineers today.

Based on courses thaught by the authors, this advanced textbook discusses opportunities for carrying out reactions on an industrial level in a technically controllable, sustainable, costeffective and safe manner.

Adopting a practical approach, it describes how miniaturized devices (mixers, reactors, heat exchangers, and separators) are used successfully for process intensification, focusing on the engineering aspects of microstrctured devices, such as their design and main chracteristics for homogeneous and multiphase reactions. It adresses the conditions under which microstructured devices are beneficial, how they should be designed, and how such devices can be integrated in an existing chemical process. Case studies show how the knowledge gained can be applied for particular processes.

The textbook is essential for master and doctoral students, as well as for professional chemists and chemical engineers working in this area.

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Preface XI

List of Symbols XIII

1 Overview of Micro Reaction Engineering 1

1.1 Introduction 1

1.2 What are Microstructured Devices? 2

1.3 Advantages of Microstructured Devices 2

1.3.1 Enhancement of Transfer Rates 2

1.3.2 Enhanced Process Safety 5

1.3.3 Novel OperatingWindow 7

1.3.4 Numbering-Up Instead of Scale-Up 7

1.4 Materials and Methods for Fabrication of Microstructured Devices 9

1.5 Applications of Microstructured Devices 10

1.5.1 Microstructured Reactors as Research Tool 11

1.5.2 Industrial/Commercial Applications 11

1.6 Structure of the Book 13

1.7 Summary 13

References 14

2 Basis of Chemical Reactor Design and Engineering 19

2.1 Mass and Energy Balance 19

2.2 Formal Kinetics of Homogenous Reactions 21

2.2.1 Formal Kinetics of Single Homogenous Reactions 22

2.2.2 Formal Kinetics of Multiple Homogenous Reactions 24

2.2.3 Reaction Mechanism 25

2.2.4 Homogenous Catalytic Reactions 26

2.3 Ideal Reactors andTheir Design Equations 29

2.3.1 Performance Parameters 29

2.3.2 BatchWise-Operated Stirred Tank Reactor (BSTR) 30

2.3.3 Continuous Stirred Tank Reactor (CSTR) 35

2.3.4 Plug Flow or Ideal Tubular Reactor (PFR) 39

2.4 Homogenous Catalytic Reactions in Biphasic Systems 45

2.5 Heterogenous Catalytic Reactions 49

2.5.1 Rate Equations for Intrinsic Surface Reactions 50

2.5.2 Deactivation of Heterogenous Catalysts 57

2.6 Mass and Heat Transfer Effects on Heterogenous Catalytic Reactions 59

2.6.1 External Mass and Heat Transfer 60

2.6.2 Internal Mass and Heat Transfer 69

2.6.3 Criteria for the Estimation of Transport Effects 83

2.7 Summary 84

2.8 List of Symbols 86

References 87

3 Real Reactors and Residence Time Distribution (RTD) 89

3.1 Nonideal Flow Pattern and Definition of RTD 89

3.2 Experimental Determination of RTD in Flow Reactors 91

3.2.1 Step Function Stimulus-Response Method 92

3.2.2 Pulse Function Stimulus-Response Method 93

3.3 RTD in Ideal Homogenous Reactors 95

3.3.1 Ideal Plug Flow Reactor 95

3.3.2 Ideal Continuously Operated Stirred Tank Reactor (CSTR) 95

3.3.3 Cascade of Ideal CSTR 96

3.4 RTD in Nonideal Homogeneous Reactors 98

3.4.1 Laminar Flow Tubular Reactors 98

3.4.2 RTD Models for Real Reactors 100

3.4.3 Estimation of RTD in Tubular Reactors 105

3.5 Influence of RTDon the Reactor Performance 107

3.5.1 Performance Estimation Based on Measured RTD 108

3.5.2 Performance Estimation Based on RTD Models 110

3.6 RTD in Microchannel Reactors 115

3.6.1 RTD of Gas Flow in Microchannels 117

3.6.2 RTD of Liquid Flow in Microchannels 118

3.6.3 RTD of Multiphase Flow in Microchannels 122

3.7 List of Symbols 126

References 127

4 Micromixing Devices 129

4.1 Role of Mixing for the Performance of Chemical Reactors 129

4.2 Flow Pattern and Mixing in Microchannel Reactors 136

4.3 Theory of Mixing in Microchannels with Laminar Flow 137

4.4 Types of Micromixers and Mixing Principles 143

4.4.1 Passive Micromixer 144

4.4.2 Active Micromixers 154

4.5 Experimental Characterization of Mixing Efficiency 158

4.5.1 Physical Methods 158

4.5.2 Chemical Methods 159

4.6 Mixer Efficiency and Energy Consumption 171

4.7 Summary 172

4.8 List of Symbols 173

References 173

5 Heat Management by Microdevices 179

5.1 Introduction 179

5.2 Heat Transfer in Microstructured Devices 181

5.2.1 Straight Microchannels 181

5.2.2 Curved Channel Geometry 189

5.2.3 Complex Channel Geometries 191

5.2.4 Multichannel Micro Heat Exchanger 191

5.2.5 Microchannels with Two Phase Flow 193

5.3 Temperature Control in Chemical Microstructured Reactors 195

5.3.1 Axial Temperature Profiles in Microchannel Reactors 197

5.3.2 Parametric Sensitivity 201

5.3.3 Multi-injection Microstructured Reactors 212

5.4 Case Studies 221

5.4.1 Synthesis of 1,3-Dimethylimidazolium-Triflate 221

5.4.2 Nitration of Dialkyl-Substituted Thioureas 222

5.4.3 Reduction of Methyl Butyrate 223

5.4.4 Reactions with Grignard Reagent in Multi-injection Reactor 224

5.5 Summary 226

5.6 List of Symbols 226

References 228

6 Microstructured Reactors for Fluid–Solid Systems 231

6.1 Introduction 231

6.2 Microstructured Reactors for Fluid–Solid Reactions 232

6.3 Microstructured Reactors for Catalytic Gas-Phase Reactions 233

6.3.1 Randomly Micro Packed Beds 233

6.3.2 Structured Catalytic Micro-Beds 235

6.3.3 CatalyticWall Microstructured Reactors 238

6.4 Hydrodynamics in Fluid–Solid Microstructured Reactors 239

6.5 Mass Transfer in Catalytic Microstructured Reactors 243

6.5.1 Randomly Packed Bed Catalytic Microstructured Reactors 244

6.5.2 Catalytic Foam Microstructured Reactors 245

6.5.3 CatalyticWall Microstructured Reactors 246

6.5.4 Choice of Catalytic Microstructured Reactors 253

6.6 Case Studies 255

6.6.1 Catalytic Partial Oxidations 255

6.6.2 Selective (De)Hydrogenations 257

6.6.3 Catalytic Dehydration 259

6.6.4 Ethylene Oxide Synthesis 259

6.6.5 Steam Reforming 260

6.6.6 Fischer–Tropsch Synthesis 261

6.7 Summary 261

6.8 List of Symbols 262

References 262

7 Microstructured Reactors for Fluid–Fluid Reactions 267

7.1 Conventional Equipment for Fluid–Fluid Systems 267

7.2 Microstructured Devices for Fluid–Fluid Systems 268

7.2.1 Micromixers 269

7.2.2 Microchannels 271

7.2.3 Microstructured Falling Film Reactor for Gas–Liquid Reactions 272

7.3 Flow Patterns in Fluid–Fluid Systems 273

7.3.1 Gas–Liquid Flow Patterns 273

7.3.2 Liquid–Liquid Flow Patterns 280

7.4 Mass Transfer 284

7.4.1 Mass Transfer Models 285

7.4.2 Characterization of Mass Transfer in Fluid–Fluid Systems 286

7.4.3 Mass Transfer in Gas–Liquid Microstructured Devices 287

7.4.4 Mass Transfer in Liquid–Liquid Microstructured Devices 296

7.4.5 Comparison with Conventional Contactors 299

7.5 Pressure Drop in Fluid–Fluid Microstructured Channels 300

7.5.1 Pressure Drop in Gas–Liquid Flow 301

7.5.2 Pressure Drop in Liquid–Liquid Flow 304

7.6 Flow Separation in Liquid–Liquid Microstructured Reactors 307

7.6.1 Conventional Separators 308

7.6.2 Types of Microstructured Separators 308

7.6.3 Conventional Separator Adapted for Microstructured Devices 315

7.7 Fluid–Fluid Reactions in Microstructured Devices 315

7.7.1 Examples of Gas–Liquid Reactions 317

7.7.2 Examples of Liquid–Liquid Reactions 319

7.8 Summary 323

7.9 List of Symbols 324

References 325

8 Three-Phase Systems 331

8.1 Introduction 331

8.2 Gas–Liquid–Solid Systems 331

8.2.1 Conventional Gas–Liquid–Solid Reactors 331

8.2.2 Microstructured Gas–Liquid–Solid Reactors 333

8.3 Gas–Liquid–Liquid Systems 346

8.4 Summary 347

8.5 List of Symbols 347

References 348

Index 351