I i Green Chemical Engineering An Introduction to Catalysis, Kinetics, and Chemical Processes S. Suresh and S. Sundaramoorthy CRC Press Taylor & Francis Group Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Croup, an informa business i
Contents Foreword Preface Acknowledgements Authors Nomenclature xiii xv xix xxi xxiii 1 Introduction 1 1.1 Principles of Green Chemistry and Green Chemical Engineering 2 1.2 Chemical Reaction Engineering: The Heart of Green Chemical Engineering 4 Section I Kinetics, Catalysis and Chemical Reactors 2 Introduction to Kinetics and Chemical Reactors 9 2.1 Kinetics of Chemical Reactions 9 2.1.1 Reaction Rate 9 2.1.2 Extent of Conversion 10 2.1.3 Rate Equation 11 2.1.3.1 Activation Energy and Heat of Reaction 11 2.1.3.2 Limiting Reactant 14 2.1.4 Elementary and Non-Elementary Reactions 15 2.1.5 Reversible Reactions 16 2.1.6 Determination of Rate Equations for Single Reactions from Batch Reactor Data 17 2.1.6.1 A Graphical Method for the Estimation of k and n 21 2.1.6.2 Estimation of Kinetic Parameters for the Reaction between Reactants A and B 23 2.1.7 Integrated Forms of Kinetic Rate Equations for Some Simple Reactions 24 2.1.7.1 First-Order Reaction 24 2.1.7.2 Second-Order Reaction 25 2.1.7.3 Third-Order Reaction 27 2.1.7.4 Second-Order Irreversible Reaction between A and B 28 2.1.7.5 Reversible First-Order Reaction 29 2.1.7.6 Zero-Order Reaction 30 2.1.8 Multiple Reactions 39 2.1.8.1 Series Reaction 39 2.1.8.2 Parallel Reaction 43 2.1.9 Autocatalytic Reactions 45 2.1.10 Non-Elementary Reactions and Stationary State Approximations 47 2.1.10.1 Estimation of Kinetic Parameters for Non-Elementary Reactions by Linear Regression 48 vii
viii Contents 2.1.11 Catalysis: Mechanism of Catalytic Reactions A Brief Introduction... 52 2.1.11.1 Kinetics of Solid Catalysed Chemical Reactions: Model 53 Langmuir-Hinshelwood Biochemical Reactions 62 2.1.12 Kinetics of Enzyme-Catalysed 2.2 Chemical Reactors: An Introduction 67 2.2.1 Homogeneous Reactors: Holding Vessels 67 2.2.1.1 Ideal Continuous Stirred Tank Reactor (CSTR) 69 2.2.1.2 Ideal Tubular Reactor 70 2.2.2 Heterogeneous Reactors Mass Transfer Equipment 73 2.2.2.1 Heterogeneous Catalytic Reactors 76 Appendix 2A: Catalysis and Chemisorption 79 2A.1 Catalysis: An Introduction 79 2A.1.1 Types of Catalysis 79 2A.1.2 An Overview of the Basic Concepts of Catalysis 82 2A.2 Heterogeneous Catalysis and Chemisorption 82 2A.2.1 Adsorption Isotherms 83 2A.3 Catalyst Deactivation and Regeneration 86 2A.4 Case Studies: Removal of Pollutants by Adsorption 88 2A.4.1 Adsorptive Removal of Phenol by Activated Palash Leaves 88 2A.4.2 Adsorptive Removal of Various Dyes by Synthesised Zeolite 98 2A.5 Conclusions 106 Appendix 2B: Fitting Experimental Data to Linear Equations by Regression 106 2B.1 Fitting Experimental Data to Linear Equations by Regression 106 2B.2 Fitting Data to a Linear Equation of the Type y Excercise Problems = + a2x2 + x0 108 MATLAB Programs 114 Ill 3 Homogeneous Reactors 135 3.1 Homogeneous Ideal Reactors 135 3.1.1 Design Equations for Ideal Reactors 135 3.1.1.1 Design Equation for First-Order Irreversible Reaction 137 3.1.1.2 Design Equation for Second-Order Irreversible Reaction 137 3.1.1.3 Design Equation for First-Order Reversible Reaction 138 3.1.2 Graphical Procedure for Design of Homogeneous 3.1.3 Multiple Reactors 143 Reactors: Reactors Connected in Series 147 3.1.3.1 System of N Numbers of Ideal CSTRs in Series 147 3.1.3.2 Optimal Sizing of Two CSTRs Connected in Series 154 3.1.3.3 CSTR and PFR in Series 157 3.1.4 Design of Reactors for Multiple 3.1.4.1 Design of CSTR for Chain Polymerisation Reactions 163 Reaction 169 3.1.5 Non-Isothermal Reactors 174 3.1.5.1 Design Equations for Non-Isothermal Reactors 175 3.1.5.2 Optimal Progression of Temperature for Reversible Exothermic Reactions 177 3.1.5.3 Design of Non-Isothermal Reactors with and without Heat Exchange Q 183
Contents ix 3.1.5.4 Non-Isothermal CSTR Operation: Multiple Steady States and Stability 193 3.2 Homogeneous Non-Ideal Reactors 197 3.2.1 Non-Ideal Reactors versus Ideal Reactors 197 3.2.2 Non-Ideal Mixing Patterns 198 3.2.3 Residence Time Distribution: A Tool for Analysis of Fluid Mixing Pattern 200 3.2.3.1 Tracer Experiment 202 3.2.3.2 Mean 0 and Variance a2 of Residence Time Distribution 206 3.2.3.3 Residence Time Distribution for Ideal Reactors 206 3.2.3.4 RTD as a Diagnostic Tool 210 3.2.4 Tanks in Series Model 210 3.2.4.1 Estimation of Parameter N 215 3.2.4.2 Conversion according to Tanks in Series Model 216 3.2.5 Axial Dispersion Model 219 3.2.5.1 Conversion according to Axial Dispersion Model 223 3.2.6 Laminar Flow Reactor 231 3.2.6.1 Conversion in Laminar Flow Reactor 233 3.2.7 Non-Ideal CSTR with Dead Zone and Bypass 237 3.2.7.1 Conversion according to Non-Ideal CSTR with Dead Zone and Bypass 239 3.2.8 Micro-Mixing and Segregated Flow 244 3.2.8.1 Micro-Mixing and the Order of Reaction 248 3.2.8.2 Conversion of a First-Order Reaction in Ideal Reactors with Completely Segregated Flow 250 3.2.8.3 Micro-Mixing and Ideal PFR 252 Appendix 3A: Estimation of Peclet Number Derivation of Equation Using Method of Moments 254 Exercise Problems 258 MATLAB Programs 262 4 Heterogeneous Reactors 289 4.1 Heterogeneous Non-Catalytic Reactors 289 Gas-Solid Reactions 289 4.1.1 Heterogeneous 4.1.1.1 Shrinking Core Model 291 4.1.1.2 Reactors for Gas-Solid Reactions 299 4.1.2 Heterogeneous Gas-Liquid Reactions 317 4.1.2.1 Derivation of Global Rate Equations 320 4.1.2.2 Design of Packed Bed Reactors for Gas-Liquid Reactions... 327 Reactions and Reactors 334 4.2 Heterogeneous Catalytic 4.2.1 Reaction in a Single Catalyst Pellet 334 4.2.1.1 Internal Pore Diffusion and Reaction in a Slab-Shaped Catalyst 4.2.1.2 Internal Pore Diffusion and Reaction in a Spherical Catalyst Pellet 337 Pellet 341 4.2.1.3 Modified Thiele Modulus <t>' 346 4.2.1.4 Modification of the Thiele Modulus for a Reversible Reaction 348
x Contents 4.2.1.5 Diffusion and Reaction in a Single Cylindrical Pore within the Catalyst Pellet 350 4.2.1.6 Global Rate Equation 353 4.2.2 Catalytic Reactors 354 4.2.2.1 Two-Phase Catalytic Reactors 355 4.2.2.2 Three-Phase Catalytic Reactors 365 Exercise Problems 370 MATLAB Programs 372 Section II Green Chemical Processes and Applications 5 Green Reactor Modelling 395 5.1 Novel Reactor Technology 395 5.1.1 Micro-Reactor 395 5.1.1.1 Characteristics of Micro-Reactors 396 5.1.2 Microwave Reactor 399 5.1.3 High-Pressure 5.1.4 Spinning Disk Reactor 400 Reactor 400 5.2 Some Reactor Design Software and Their Applications 402 5.2.1 gproms: For Simulation and Modelling of Reactors 402 5.2.2 ANSYS Reactor Design 403 5.2.2.1 Computational Fluid Dynamics 403 5.2.2.2 CFD Modelling of Multiphase Systems 407 5.3 ASPEN Plus Simulation of RCSTR Model 418 5.3.1 Simulation of CSTR Model 419 5.3.2 Conclusions 427 and Processes 429 6 Application of Green Catalysis 6.1 Introduction to Application of Green Catalysis and Processes 430 6.2 Case Study 1: Treatment of Industrial Effluents Using Various Green Catalyses 431 6.2.1 Introduction 432 6.2.1.1 Properties of Zeolites 434 6.2.1.2 Zeolite Na-Y 436 6.2.1.3 Applications of Zeolites 440 6.2.2 Adsorption of Dyes onto Zeolite 442 6.2.2.1 Acid Orange 7 Dye 443 6.2.2.2 Methyl Orange Dye 443 6.2.2.3 Methylene Blue 443 6.2.2.4 Safranine Dyes 444 6.2.3 Catalytic WPO 445 6.2.3.1 Experimental Design 445 6.2.3.2 Results and Discussions 451 6.2.3.3 Conclusions and Recommendations 459 6.3 Case Study 2: Thermolysis of Petrochemical Industrial Effluent 466 6.3.1 Source of Wastewater 467 6.3.2 Experimental Procedure 467 6.3.3 Kinetic Studies 468
Contents xi 6.3.4 Results and Discussion 470 6.3.5 Conclusions 472 6.4 Case Study 3: Catalytic Wet-Air Oxidation Processes 474 6.4.1 Introduction 475 6.4.1.1 Alcohol Production in India 476 6.4.1.2 Wastewater Generation and Characteristics 479 6.4.1.3 Wastewater Treatment Methods 481 6.4.1.4 Drawbacks of Different Technologies 481 6.4.1.5 Wet Air Oxidation 482 6.4.2 Literature Survey 483 6.4.3 Experimental Setup and Design 486 6.4.4 Results and Discussions 486 6.4.5 Conclusions 491 References 493 Further Reading 499 Index 501