Catalyst Separation, Recovery and Recycling (eBook)

TABLE OF CONTENTS 6
CHAPTER 1 HOMOGENEOUS CATALYSIS – ADVANTAGES AND PROBLEMS 11
1.1 Catalysis 11
1.2 Catalyst Stability 14
1.3 Layout of the Book 16
1.4 References 18
CHAPTER 2 CLASSICAL HOMOGENEOUS CATALYST SEPARATION TECHNOLOGY 19
2.1 Coverage of Chapter 19
2.2 General Process Considerations 19
2.3 Everything is a Reactor 20
2.4 Overview of Separation Technologies 20
2.5 Hypothetical processes - How might the Product be separated from the Catalyst? 28
2.6 Real-World Complications 32
2.8 Concluding Remarks 45
2.9 References 46
CHAPTER 3 SUPPORTED CATALYSTS 49
3.1 Introduction 49
3.2 Short Historical Overview 50
3.3 Polystyrene Supported Catalysts 51
3.4 Silica Supported Catalyst 54
3.5 Catalysis in Interphases 63
3.6 Ordered esoporous Support 68
3.7 Non- covalently Supported Catalysts 70
3.8 Supported Aqueous Phase Catalysis 73
3.10 Concluding Remarks 78
3.11 References 79
CHAPTER 4 SEPARATION BY SIZE-EXCLUSION FILTRATION 83
4.1 Introduction 83
4.2 Reactors 84
4.3 Membranes 88
4.4. Dendrimer Supported Catalysts 90
4.5 Dendritic Effects 100
4.6 Unmodified or Non-dendritic Catalysts 104
4.7 Soluble Polymer Supported Catalysts 108
4.8 Concluding Remarks 112
4.9 References 112
CHAPTER 5 BIPHASIC SYSTEMS: WATER – ORGANIC 115
5.1 Introduction 115
5.2 Immobilization with the Help of Liquid Supports 116
5.3 Recycle and Recovery of Aqueous Catalysts 134
5.4 Concluding Remarks 144
5.5 References 145
CHAPTER 6 FLUOROUS BIPHASIC CATALYSIS 155
6.1 Introduction 155
6.2 Alkene Hydrogenation 158
6.3 Alkene Hydrosilation 161
6.4 Alkene Hydroboration 161
6.5 Alkene Hydroformylation 162
6.6 Alkene Epoxidation 168
6.7 Other Oxidation Reactions 171
6.8 Allylic Alkylation 173
6.9 Heck, Stille, Suzuki , Sonagashira and Related Coupling Reactions 174
6.10 Asymmetric Alkylation of Aldehydes 176
6.11 Miscellaneous Catalytic Reactions 179
6.12 Fluorous Catalysis without Fluorous Solvents 180
6.13 Continuous Processing 181
6.14 Process Synthesis for the Fluorous Biphasic Hydroformylation of 1- Octene 185
6.15 Conclusions 188
6.16 Acknowledgement 189
6.17 References 189
CHAPTER 7 CATALYST RECYCLING USING IONIC LIQUIDS 193
7.1. Introduction 193
7.2. Liquid- liquid iphasic, Rh- catalysed Hydroformylation Using Ionic Liquids 202
7.3 Rhodium Catalysed Hydroformylation Using Supported Ionic Liquid Phase SILP) Catalysis 211
7.4 Costs and Economics 216
7.5 Conclusions 219
7.6 References 220
CHAPTER 8 SUPERCRITICAL FLUIDS 225
8.1 Introduction to Supercritical Fluids 225
8.2 Applications of scCO in Catalyst Immobilisation 227
8.2 Applications of scCO 227
8.3. Economic Evaluation and Summary 242
8.4 Summary 244
8.5 References 244
CHAPTER 9 AREAS FOR FURTHER RESEARCH 247
9.1 Introduction 247
9.2 Conventional separation methods (See Chapter 2) 248
9.3 Catalysts on insoluble supports (Chapter 3) 250
9.4 Catalysts on soluble supports (Chapter 4) 251
9.5 Aqueous biphasic catalysis (Chapter 5) 252
9.6 Fluorous biphasic catalysis (Chapter 6) 253
9.7 Reactions involving ionic liquids (Chapter 7) 254
9.8 Reactions using supercritical fluids (Chapter 8) 255
9.9 Conclusions 257
9.10 References 257

CHAPTER 2 CLASSICAL HOMOGENEOUS CATALYST SEPARATION TECHNOLOGY (p. 9)

DAVID R. BRYANT
2.1 Coverage of Chapter
When considering a separation technique for a homogeneous catalytic process, one must realize that catalyst/product/byproduct separation is an integral part of the entire process. The selection and design of the separation technology goes hand-in-hand with catalyst design, often in an iterative fashion.

That is, a catalyst is selected and tested in a continuous unit, with recycle of streams, to discover if there are problems that will necessitate redesign of the catalyst. Redesign is more often the fact than the exception. The objective of this chapter is to detail considerations that must be addressed in order to successfully marry a catalyst technology with catalyst/product separation technology. The focus of this chapter is hydroformylation, but the general principles should apply to many homogeneous precious-metal catalyzed processes.

2.2 General Process Considerations

There are four principal factors that are paramount in selecting the best separation technique. They are the energy required for the separation, the capital required for the equipment used in the separation, the efficiency/effectiveness of the separation, and the vitality of the catalyst after the separation. General process considerations include: Transitions of any type including temperature, pressure or phase changes should be minimized.

Cooling below 40 degrees Celsius becomes more expensive (river water cannot be used). Vacuum below 20 mm Hg is challenging. Byproduct formation should be minimized. Single product processes are better. A distillation column, or other step, will be required for each material in the mixture.

Everything feasible should be recycled so as to minimize waste. Pressures should be kept below 35 bar, at least below 100 bar, to minimize costs and because most process design experience is here. The use of rotating equipment such as compressors or centrifuges should be minimized to minimize maintenance costs.

Corrosive materials, particularly chloride, should be avoided. Batch operations should be avoided. The handling of solids should be avoided.

2.3 Everything is a Reactor

This may be a good time to introduce a very simple principal of process chemistry, but one that is not widely recognized. It is taught in chemical engineering that the only things in chemistry that matter are temperature and concentration. Every other variable can be reduced to these two. For example, time is simply a reflection of changing concentration.

Now a corollary: since every piece of process equipment has associated with it temperature and concentration, all pieces of process equipment are reactors. Stated differently, everything is a reactor.

There is a tendency to think that once the catalyst is removed from the reactor, all chemistry ceases. Chemistry is occurring throughout the process, and that is why separation of products cannot be viewed in isolation from the process that made them.

2.4 Overview of Separation Technologies

2.4.1 TRADITIONAL COBALT WITH CATALYST DECOMPOSITION

Traditional cobalt hydroformylation separations will not be covered in detail since they have been described in many excellent references.