Membrane Science and Technology Series, 4 FUNDAMENTALS OF INORGANIC MEMBRANE SCIENCE AND TECHNOLOGY Edited by A.J. Burggraaf Laboratory of Inorganic Materials Science, Faculty of Chemical Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands and L. Cot Laboratory des Materiaux et Procedes Membranes, (UMR 9987 CNRS-ENSCM-4411), Ecole Nationale Superieure de Chimie 8 Rue de l'ecole de Chimie, 34053 Montpellier, France 1996 ELSEVIER Amsterdam Lausanne New York Oxford Shannon Tokyo
vii Contents Preface List of contributors v xvii Chapter 1. GENERAL OVERVIEW, TRENDS AND PROSPECTS A.J. Burggraaf and L. Cot 1.1 Introduction 1 1.2 Market Situation and Prospects 2 1.3 Main Barriers to Technological Development and Acceptance 3 1.3.1 Requirements and Issues 3 1.3.1.1 Characteristics of ceramic fabrication 4 1.3.2 State of the Art and Needs 5 1.3.2.1 Availability and cost 5 1.3.2.2 Reliability 6 1.3.2.3 Long-term stability 6 1.3.2.4 Surface area to volume ratio 7 1.3.2.5 Specific combinations of high Separation factors and high permeation 7 1.4 Trends, Technological and Scientific Prospects 9 1.4.1 Infrastructure for Future Work 9 1.4.2 Some Trends 10 1.4.3 Prospects for Interesting Membrane Applications 12 1.4.3.1 Industrial production processes 12 1.4.3.2 Energy-related applications 13 1.4.3.3 Environmental applications 13 1.4.3.4 Others 14 1.4.4 Interesting Fields for Future R&D 14 1.4.4.1 Long-term chemical stability 15 1.4.4.2 Thin-layer deposition technology 15 1.4.4.3 Support technology 15 1.4.4.4 Microporous membranes for gas/vapour Separation... 16 1.4.4.5 Nanofiltration membranes 17 1.4.4.6 Dense (non-porous) membranes and surface reaction limitation 18 1.4.4.7 Mixed (hybrid) processes and materials 19 References 19 Chapter 2. IMPORTANT CHARACTERISTICS OF INORGANIC MEMBRANES A.J. Burggraaf 2.1 Introduction 21 2.2 Types of Inorganic Membranes 21
vm 2.3 Microstructural Pore and Pore Network Characteristics 23 2.3.1 Modified Structures 26 2.3.2 Supports 27 2.4 Architecture of Membrane Systems 27 2.5 Some General Characteristics 31 2.5.1 Commercially Available Inorganic Membranes 31 2.6 Considerations on Chemical Resistance 33 References 34 Chapter 3. ADSORPTION PHENOMENA IN MEMBRANE SYSTEMS Yi Hua Ma 3.1 Introduction 35 3.2 Adsorption Isotherms 36 3.2.1 Types of Isotherms 36 3.2.2 The Langmuir Isotherm 37 3.2.3 The BET Isotherms 40 3.2.4 Isotherms Derived from the Equation of State 41 3.2.5 The Potential Theory 42 3.3 Experimental Techniques 43 3.3.1 Determination of Adsorption Isotherms 43 3.3.2 Surface Area Determinations 46 3.3.3 Pore Size Distribution 49 3.4 Adsorption on Membranes 57 3.4.1 Adsorption of Gases on Microporous Silica Membranes and Interrelation between Adsorption and Permeation 57 3.4.2 Adsorption on Sol-Gel Derived Ceramic Membranes 60 3.4.3 Liquid Adsorption on Membranes 61 3.5 Summary 64 References 64 Chapter 4. METHODS FOR THE CHARACTERISATION OF POROUS STRUCTURE IN MEMBRANE MATERIALS A. Julbe and J.D.F. Ramsay 4.1 General Introduction 67 4.2 Description of Porous Materials Definitions 69 4.2.1 Origin of Pore Structure 69 4.2.2 Quantitative Description of Pore Structures 70 4.2.3 Models for Porous Structures 72 4.3 Static Characterisation Techniques 74 4.3.1 Stereology 74 4.3.2 Intrusive Methods 78 4.3.2.1 Mercury porosimetry 78 4.3.2.2 Gas adsorption/desorption isotherms (physisorption)... 78 4.3.2.3 Calorimetric determinations 84 4.3.2.4 Nuclear magnetic resonance 87 4.3.3 Non-intrusive Methods 91
4.3.3.1 Radiation scattering 91 4.3.3.2 Wave propagation 94 4.3.3.3 Ion-beam analysis 96 4.3.3.4 Positron lifetime spectroscopy 97 4.4 Dynamic Characterisation Techniques 98 4.4.1 Rejection Measurements 98 4.4.2 Liquid Displacement Techniques 99 4.4.2.2 Liquid/gas methods (bubble point, liquid expulsion permporometry) 99 4.4.2.3 Liquid-liquid displacement porosimetry (or biliquid permporometry) 101 4.4.3 Fluid Flow Measurements 102 4.4.3.1 Liquid permeability 102 4.4.3.2 Gas permeability 103 4.4.3.3 Permporometry 104 4.5 Conclusion and Recommendations 106 References 110 Chapter 5. CERAMIC PROCESSING TECHNIQUES OF SUPPORT SYSTEMS FOR MEMBRANES SYNTHESIS A. Larbot 5.1 Introduction 119 5.2 Extrusion 121 5.2.1 Ceramic Paste Preparation 121 5.2.2 Tube Shaping, Drying and Firing 124 5.2.3 An Example of Preparation 127 5.3 Tape Casting 130 5.3.1 Slurry Preparation 131 5.3.2 Shaping and Fiat Ceramics 133 5.4 Specific Characterization Methods for Supports 134 5.4.1 Bubble Point 134 5.4.2 Mechanical Resistance 136 5.4.2.1 Burst pressure (test for tubes) 136 5.4.2.2 Bending strength (test for cylindrical specimen) 136 5.5 Conclusion 137 References 138 Chapter 6. PREPARATION OF ASYMMETRIC CERAMIC MEMBRANE SUPPORTS BY DIP-COATING B.C. Bonekamp 6.1 Introduction 141 6.2 Supports for Ceramic Membranes 143 6.2.1 The Multilayer Support System 143 6.2.2 Support Requirements 146 6.2.3 Layer Formation on Porous Substrates 150 6.2.4 Suspensions and Sols 159 ix
X 6.2.4.1 Van der Waals attraction 163 6.2.4.2 Electrostatic interaction 164 6.2.4.3 Polymerie interaction 166 6.2.4.4 Rheology 171 6.2.5 Drying and Sintering of Particulate Coatings 175 6.2.6 Defects 178 6.3 Dip-coating with Porous Substrates 183 6.3.1 Capillary Colloidal Filtration 183 6.3.1.1 Continuum description 184 6.3.2 Film-coating 189 6.3.2.1 Coating flow dynamics 190 6.3.2.2 Closer examination 191 6.3.2.3 Substrate wetting and dewetting 195 6.3.2.4 Stability of liquid coatings 200 6.3.3 Macromolecular Thickeners and Binders 203 6.3.4 Compact (Cake) Structure 207 6.4 Applications 209 6.5 Final Remarks 218 Acknowledgements 218 List of Symbols 219 References 221 Chapter 7. SOL-GEL CHEMISTRY AND ITS APPLICATION TO POROUS MEMBRANE PROCESSING Christian Guizard 7.1 Introduction 227 7.2 Pore Formation in Sol-Gel Derived Ceramic Membranes 229 7.2.1 Packing of Colloidal Particles 229 7.2.2 Aggregation of Clusters 230 7.2.3 Utilization of Template Agents 231 7.3 Colloidal Suspensions to Prepare Mesoporous Membranes 232 7.3.1 Chemistry of Colloidal Sols 232 7.3.2 Examples of Membrane Preparation 233 7.4 Inorganic Polymers to Prepare Microporous Membranes 237 7.4.1 Formation and Aggregation of Clusters 237 7.4.2 Examples of Membrane Preparation 239 7.5 The Concept of Nanophase Ceramics Applied to the Preparation of Microporous Membranes 240 7.5.1 Formation and Coating of Aqueous Nanoparticulate Sols 240 7.5.2 Formation and Coating of Organic Nanoparticulate Sols 243 7.6 Tailor-made Porous Membranes via Templates Containing Systems... 245 7.6.1 Utilization of Amphiphilic Media 246 7.6.2 Insertion of Organic and Inorganic Entities or Polymer Particles in Gel Layers 251 7.7 Conclusion 254 References 255
Chapter 8. FUNDAMENTALS OF MEMBRANE TOP-LAYER SYNTHESIS AND PROCESSING A.J. Burggraaf 8.1 Synthesis and Processing of Supported Mesoporous Membranes 259 8.1.1 Introduction 259 8.1.2 Film Formation 260 8.1.2.1 Initial layer formation 260 8.1.2.2 Mesoporous film formation 261 8.1.2.3 Theoretical aspects of the drying process from lyogel to xerogel film 271 8.1.2.4 Consolidation to the final membrane structure by heating 280 8.1.3 Illustrative Experimental Observations of Stress and Cracking in Membranes 283 8.1.3.1 Stress measurements in supported porous membranes.. 283 8.1.3.2 Drying characteristics of membranes 287 8.1.3.3 Stress and cracking in membranes during drying 287 8.1.3.4 Stress formation in membranes during calcination... 291 8.1.3.5 A model discussion of stress and avoiding cracking.... 292 8.1.4 Thermal Stability of Ceramic Membranes 297 8.2 Synthesis and Processing of Supported Microporous Membranes 298 8.2.1 Microporous Membranes Obtained by Sol-Gel Processes 298 8.2.1.1 Introduction and overview of film formation 298 8.2.1.2 Important parameters in precursor synthesis 300 8.2.1.3 Illustrative examples of membrane synthesis and microstructure development 306 8.2.2 Microporous Membranes Obtained by CVD 310 8.2.2.1 CVD methods 310 8.2.2.2 Other methods and microporous membrane Systems... 312 8.2.3 Zeolite Membranes 312 8.2.3.1 Overview and introduction to zeolite chemistry 312 8.2.3.2 Illustrative examples of zeolite membrane synthesis and processing 317 8.3 Conclusions and Evaluation 322 References 324 Chapter 9. TRANSPORT AND SEPARATION PROPERTIES OF MEMBRANES WITH GASES AND VAPOURS A.J. Burggraaf 9.1 Introduction 331 9.1.1 Chapter Outline 331 9.1.2 Overview of Important Points 332 9.2 Gas Transport in Simple Membrane Structures 333 9.2.1 Important Concepts 333 9.2.2 Pore Characteristics and Membrane Architecture 335 9.2.3 Single Gas Permeation in Macroporous and Mesoporous Systems. 337 9.2.3.1 Viscousflow 337 xi
xii 9.2.3.2 Knudsen diffusion and the transition region 338 9.2.3.3 Surface diffusion and capillary condensation 345 9.2.4 Permeation in binary gas mixtures in macroporous and mesoporous membranes 355 9.2.4.1 General considerations 355 9.2.4.2 Knudsen diffusion 357 9.2.4.3 Viscous Flow and the Transition Region 357 9.3 Separation of Binary Mixtures in Simple Mesoporous Membranes 364 9.3.1 Important Concepts 364 9.3.2. Separation in the Knudsen and Transition Regions 365 9.3.3 Separation with Surface Diffusion and Capillary Condensation.. 368 9.4 Permeation and Separation in Microporous Membranes 374 9.4.1 Introduction and Important Concepts 374 9.4.2 Phenomenological Description of Single Gas Permeation 377 9.4.2.1 Qualitative description of gas permeation 378 9.4.2.2 Quantitative description of gas permeation and Separation 382 9.4.2.3 Permeation and Separation in binary (ternary) gas mixtures 386 9.4.2.4 Illustrative examples of permeation and Separation with microporous membranes 391 9.4.4 Surface Effects on Permeation in Microporous Membranes 411 9.5 Permeation and Separation in More Complicated Systems 413 9.5.1 HollowFibres 413 9.5.2 Multilayered, Asymmetrie Supported Systems 414 9.6 Overview of Important Results 416 9.6.1 Introductory Remarks 417 9.6.2 Typical Permeation and Separation Data for Porous Membranes.. 418 9.6.3 Comparison of Permeation and Separation Data of Porous and Dense Membranes 422 9.7 Conclusions and Evaluation 424 List of Symbols 425 References 427 Chapter 10. DENSE CERAMIC MEMBRANES FOR OXYGEN SEPARATION H.J.M. Bouwmeester and A.J. Burggraaf 10.1 Introduction 435 10.2 General Survey 436 10.2.1 Major Membrane Concepts 436 10.2.2 Data: Oxygen Permeability of Solid Oxide Membranes 440 10.2.3 Factors Controlling Oxygen Permeation 448 10.3 Fundamentals 449 10.3.1 Bulk Transport 449 10.3.1.1 Wagner equation 449 10.3.1.2 Chemical diffusion coefficient 451
10.3.1.3 Trapping of electronic and ionic defects 453 10.3.1.4 Empirical equations 454 10.3.2 Surface Oxygen Exchange 455 10.3.2.1 Characteristic membrane thickness L c 456 10.3.2.2 MeasuringL c 459 10.3.2.3 The effect of surface roughness and porosity 461 10.4 Solid Oxide Electrolytes 462 10.4.1 Introduction 462 10.4.2.1 Diffusion of electronic Charge carriers 463 10.4.2 Oxygen Semi-permeability of Oxide Electrolytes 463 10.4.2.2 Modelling equations 464 10.4.2.3 Examples 465 10.4.3 Electrochemical Oxygen Separation 469 10.4.3.1 Oxygen pump 469 10.4.3.2 Dual-phase composites 470 10.5 Introducing Electronic Conduction in Fluorite-type Oxygen Ion Conductors 472 10.5.1 Introduction 472 10.5.2 Defect Chemistry 472 10.5.3 Examples 475 10.6 Accceptor-doped Perovskite and Perovskite-related Oxides 479 10.6.1 Introduction 479 10.6.2 Structure and Defect Chemistry 482 10.6.2.1 Perovskite Structure 482 10.6.2.2 Nonstoichiomerry 483 10.6.2.3 Localized versus Delocalized Elections 486 10.6.3 Oxygen Desorption and Perovskite Stability 488 10.6.4 Equations for Oxygen Transport 489 10.6.5 Electronic Conductivity 492 10.6.6 Extended Defects and Vacancy Ordering 495 10.6.6.1 Static Lattice Simulation 495 10.6.6.2 Vacancy Ordering 497 10.6.6.3 Microdomain Formation 498 10.6.6.4 Brownmillerite Structure 499 10.6.6.5 High Temperature NMR 500 10.6.7 Observations from Permeability Measurements 502 10.6.7.1 SrCoo.8Feo. 2 0 3^ 502 10.6.7.2 Experimental difficulties 503 10.6.7.3 Surface exchange kinetics 506 10.6.7.4 Behaviour in large Po 2 -gradients 507 10.6.7.5 Grain boundary diffusivity 508 10.7 Final Remarks 510 Acknowledgements 513 List of Abbreviations and Symbols 513 References 515
XIV Chapter 11. CURRENT DEVELOPMENTS AND FUTURE RESEARCH IN CATALYTIC MEMBRANE REACTORS Jose Sanchez and Theodore T. Tsotsis 11.1 Introduction 529 11.2 Dense Metal Membrane Reactors 532 11.2.1 Cost and Availability 534 11.2.2 Mechanical and Thermal Stability 534 11.2.3 Poisoning and Carbon Deposition Problems 535 11.3 Porous Inorganic Membrane Reactors 537 11.4 Solid Oxide Membranes 546 11.5 Theoretical Considerations 549 11.6 Emerging Applications 555 11.7 Concluding Remarks 560 Acknowledgements 561 References 561 Chapter 12. TRANSPORT AND FOULING PHENOMENA IN LIQUID PHASE SEPARATION WITH INORGANIC AND HYBRID MEMBRANES Christian Guizard and Gilbert Rios 12.1 Introduction 569 12.2 Basic Phenomena in Pressure Driven Processes 570 12.2.1 Modelling of Hydrodynamics and Mass Transport 570 12.2.2 Fouling 575 12.2.3 Specific Aspects Attached to Ceramic Membranes 581 12.3 Recent Developments in Microfiltration and Ultrafiltration with Ceramic Membranes 590 12.3.1 Hydrodynamics of Micro- and Ultrafiltration Systems 590 12.3.2 Influence of Membrane Material on Permeability and Solute Rejection 593 12.4 Nanofiltration with Ceramic Membranes 595 12.4.1 Separation of Neutral Solutes in Absence of Electrolytes 596 12.4.2 Salt Rejection of Electrolyte Solutions 598 12.4.3 Separation of Aqueous Ionized Molecule-Salt Solutions 604 12.5 Prospective Aspects 606 12.5.1 Organic-Inorganic Hybrid Membranes and Related Processes... 606 12.5.2 Coupled Membrane Processes 608 12.6 Conclusion 613 References 614 Chapter 13. APPLICATIONS OF CERAMIC MEMBRANES IN LIQUID FILTRATION C.A.M. Siskens 13.1 Introduction 619 13.2 Treatment of Wastes 620 13.2.1 Wastes of Oily Emulsions 620 13.2.1.1 Compressor-condensate 620 13.2.1.2 Centralised treatment of industrial emulsions 621
XV 13.2.1.3 Bilge water treatment 621 13.2.1.4 Vegetable waste water 622 13.2.2 Wastes Based on Semi-solids 622 13.2.2.1 Fish factory effluent 622 13.2.2.2 Manure 623 13.3 Regeneration 623 13.3.1 Recycling of Solids from Suspensions 623 13.3.1.1 Ceramics industry 623 13.3.1.2 Paintandink 624 13.3.2 Lifetime Extension of Cleaning Baths 625 13.3.2.1 Alkaline degreasing baths 625 13.3.2.2 Industrial washing Operations 625 13.3.3 Recycling in Chemical Processes 626 13.3.3.1 Cleaning of organic and inorganic reagents 626 13.3.3.2 Galvanic baths 627 13.4 Processing 627 13.4.1 Treatment of Liquid Products 627 13.4.1.1 Fruit Juices 627 13.4.1.2 Beerbrewing 627 13.4.1.3 Beer and wine clarification 628 13.4.1.4 Potable water 629 13.4.2 Treatment of Semi-solid Products 630 13.4.2.1 Proteins 630 13.4.2.2 Whey 630 13.4.2.3 Sugars 631 13.4.2.4 Paper and pulp 632 13.4.3 Biotechnology 632 Acknowledgements 634 References 634 Chapter 14. FEASIBILITY OF THE APPLICATION OF POROUS INORGANIC GAS SEPARATION MEMBRANES IN SOME LARGE-SCALE CHEMICAL PROCESSES Henk M. van Veen, Maarten Bracht, Edwin Hamoen and Peter T. Alderliesten 14.1 Introduction 641 14.2 Background Information 643 14.2.1 Materials 643 14.2.2 Membrane Reactors 645 14.2.3 Membrane Process Modelling 646 14.3 Gas Separation Applications for Inorganic Membranes 648 14.3.1 Dehydrogenation of Propane 648 14.3.1.1 Introduction 648 14.3.1.2 Thermodynamics of propane dehydrogenation 649 14.3.1.3 Adiabatic reactor concepts; reactor modelling evaluation 650 14.3.1.4 Isothermal reactor concepts; economic evaluation 654 14.3.1.5 General conclusions propane dehydrogenation 657
xvi 14.3.2 Dehydrogenation of Ethylbenzene to Styrene 657 14.3.2.1 Introduction 657 14.3.2.2 Conventional process description 658 14.3.2.3 Implementation of membranes 659 14.3.2.4 Results 661 14.3.2.5 Discussion 664 14.3.2.6 Conclusions 665 14.3.3 Water-Gas Shift Membrane Reactor 665 14.3.3.1 Introduction 665 14.3.3.2 WGS membrane reactor for CO2 emission control 667 14.3.3.4 Full-scale process considerations 672 14.3.3.5 Conclusion 672 14.4 Conclusions 673 Acknowledgements 674 List of Symbols and Abbreviations 675 Appendix 676 References 676 Subject Index 681