Session 2: Flow Chemistry Chris Rayner

Transcription

1 Session 2: Flow Chemistry Chris Rayner

2 Flow Chemistry within iprd Presentation focuses on: Track record/in house expertise (highlights) Current projects Future perspectives/targets Discussion welcomed on: Comments/suggestions on project portfolio Identification of interested partners/ consortia for collaboration, application or information exchange

3 Flow Chemistry within iprd Continuous Synthetic Chemistry Thermolytic reactions Hazardous reagents Photochemistry Equipment and modelling Rotating tube and spinning disc reactors Reactor and Reaction Modelling Microchannel reactors In-process analytics Supercritical fluids Continuous reactions and product isolation

4 Thermolytic reactions in flow (Steve Marsden) Pressurised flow reactors allow reactions to be carried out at temperatures above normal boiling point of solvent Short residence time in high temperature zone reactors for high activation energy reactions Example: thermolytic elimination of C 2 from β-lactones reduced waste synthesis of alkenes R 1 H + R 2 X high temp. R 1 R 2 -C 2 R 1 R 2

5 Thermolytic reactions in flow (Steve Marsden) Controlled residence, high temperature zone reactors for high activation energy reactions Example: controlled thermolytic generation of reactive heterocumulenes for de novo heteroaromatic synthesis ([4+2] cycloaddition followed by elimination) R 1 R 2 tbu o C R 1 R 2 Et R 1 R 2 R 1 NHR o C tbu R 1 NR 3 R 2 R 2 Et R 3 N R 1 R 2

6 Hazardous reactions (Rob Hammond) Use of hazardous reagents particularly problematic in large scale batch processes Azide and cyanide widely used in synthetic chemistry for heterocycle synthesis, introduction of N-functionality, C-1 synthon etc. Flow techniques required Hazardous scale-up, particularly if require parent acids which are highly toxic, volatile and potentially explosive Use of flow reactor to generate HCN or HN 3 in small quantities under highly controlled conditions bjective is to maximise safety and efficiency aspects in flow reactor Long term goal is to develop a reaction system that can allow large scale synthesis of intermediates using hazardous reagents

7 Continuous synthetic photochemistry (Chris Rayner) Synthetic photochemistry offers opportunities to access functionality otherwise very difficult to obtain. ften limited by poor yields and prolonged reaction times. Continuous reaction approach greatly increases yields and rates Lower power lamps Reduced decomposition Shorter reaction times Higher conversions + Ethanol hν 81% 89 % Batch, 2h Continuous, 15min Continuous, 2h, >95%

8 Continuous synthetic photochemistry (Chris Rayner) Photo-Fries rearrangement very versatile, but usually limited to ca. 40% conversion. Product build up inhibits further reaction (more intense absorption) Currently investigating biphasic approaches where product is selectively extracted as it is formed Dramatic increase in conversions, yield and rates. Lamp hν H + H Tubing around lamp 3 : 2 Batch 400W, 56h, MeCN, 10% Continuous 400W, 80h, MeCN, 54%, 3:2 Batch 125W, 12h, hexane/aq. K 2 C 3 (10:1), >95% Pump Hexane + substrate Aq. K 2 C 3 + product

9 New continuous reactors (Chris Rayner/Roshan Jachuck) pportunity for new reactor designs Rotating tube reactors (Roshan Jachuck, Clarkson, NY) Residence time of seconds to several minutes (or batch) Highly sheered films ( microns) Immiscible liquids of different densities (e.g. water/organic) form 2 independent micron scale layers Ideal for biphasic photochemistry and other two phase reactions Not prone to blocking; also good for reactions involving gases

10 Reaction modelling (Annette Taylor) Fundamental kinetic and thermodynamic analysis of reaction processes in complex systems (practical and theoretical) Modelling of features generic to any reaction containing feedback through autocatalysis or heat (thermal runaway) Examples of feedback in organic chemistry include: Addition of dialkylzinc reagents to pyrimidinecarbaldehyde (the Soai reaction) Formaldehyde-sulfite addition Polymerisations (e.g. vinyl acetate) Continuous photochemistry (e.g. [2+2] cycloadditions) Mechanistic studies on C 2 capture and release (CCS)

11 Reaction modelling (Annette Taylor) Chemical flow systems EPSRC funded project in collaboration with Mark Wilson & Melanie Britton (Birmingham) Chemical reactions in plug-flow / packed-bed / Taylor-Couette flow Influence of flow on chemical amplification (autocatalysis); chemical waves (spatial concentration profiles) Reaction-diffusion-advection simulations 2d and Dispersion 3d Simulated imaging in a of wave packed a chemical profiles bed wave Taylor, A.F.; Britton M.M. Chaos, pp , 2006, 16. Britton, M.M.; Sederman, A.J.; Taylor, A.F.; Scott S.K.; Gladden, L.F., Journal of Physical Chemistry A, pp , 2005, 109.

12 Microfluidics (Nik Kapur and Mark Wilson) Micromixing for reaction: The aim here was to use computational methods to develop a mixing device for a specific set of flow conditions. The device is currently being manufactured. Mixing by chaotic advection: This was a study of a small geometry where oscillation of the free surface (one roll speed is perturbed) causes mixing of the fluid. Shown on the movie are small tracer particles within the flow illustrating the mixing. The experiments on the left provide validation. Ambient fluid capture: The following slide shows how, using the control of eddies within flow, particles or reagents can be trapped. Autocatalytic reaction: This slide illustrates a simple autocatalytic scheme within the same geometry. Its possible to build a series of reactions into these models to couple flow and kinetics. 2 Phase droplet: An illustration of a 2-phase simulation similar to that found within a microemulsion device. This sort of method can be used to optimise geometric and flow conditions for robust droplet formation. The group also has considerable experience in experiments in this area (2-phase flow).

13 Microfluidics (Nik Kapur and Mark Wilson) For a particular oscillatory reaction, needed: Rapid mixing Uniform concentration profile Long residence time, but No stagnant regions

14 Micromixing for reaction: The aim here was to use computational methods to develop a mixing device for a specific set of flow conditions. The device is currently being manufactured. Mixing by chaotic advection: This was a study of a small geometry where oscillation of the free surface (one roll speed is perturbed) causes mixing of the fluid. Shown on the movie are small tracer particles within the flow illustrating the mixing. The experiments on the left provide validation. Ambient fluid capture: The following slide shows how, using the control of eddies within flow, particles or reagents can be trapped. Autocatalytic reaction: This slide illustrates a simple autocatalytic scheme within the same geometry. Its possible to build a series of reactions into these models to couple flow and kinetics. 2 Phase droplet: An illustration of a 2-phase simulation similar to that found within a microemulsion device. This sort of method can be used to optimise geometric and flow conditions for robust droplet formation. The group also has considerable experience in experiments in this area (2-phase flow).

15 Mixing by chaotic advection Experimental Finite element simulation

16 Micromixing for reaction: The aim here was to use computational methods to develop a mixing device for a specific set of flow conditions. The device is currently being manufactured. Mixing by chaotic advection: This was a study of a small geometry where oscillation of the free surface (one roll speed is perturbed) causes mixing of the fluid. Shown on the movie are small tracer particles within the flow illustrating the mixing. The experiments on the left provide validation. Ambient fluid capture: The following slide shows how, using the control of eddies within flow, particles or reagents can be trapped. Autocatalytic reaction: This slide illustrates a simple autocatalytic scheme within the same geometry. Its possible to build a series of reactions into these models to couple flow and kinetics. 2 Phase droplet: An illustration of a 2-phase simulation similar to that found within a microemulsion device. This sort of method can be used to optimise geometric and flow conditions for robust droplet formation. The group also has considerable experience in experiments in this area (2-phase flow).

17 Ambient field capture controlling delivery of reagents?

18 Micromixing for reaction: The aim here was to use computational methods to develop a mixing device for a specific set of flow conditions. The device is currently being manufactured. Mixing by chaotic advection: This was a study of a small geometry where oscillation of the free surface (one roll speed is perturbed) causes mixing of the fluid. Shown on the movie are small tracer particles within the flow illustrating the mixing. The experiments on the left provide validation. Ambient fluid capture: The following slide shows how, using the control of eddies within flow, particles or reagents can be trapped. Autocatalytic reaction: This slide illustrates a simple autocatalytic scheme within the same geometry. Its possible to build a series of reactions into these models to couple flow and kinetics. 2 Phase droplet: An illustration of a 2-phase simulation similar to that found within a microemulsion device. This sort of method can be used to optimise geometric and flow conditions for robust droplet formation. The group also has considerable experience in experiments in this area (2-phase flow).

19 Autocatalytic reactions For reaction R+B 2B

20 Micromixing for reaction: The aim here was to use computational methods to develop a mixing device for a specific set of flow conditions. The device is currently being manufactured. Mixing by chaotic advection: This was a study of a small geometry where oscillation of the free surface (one roll speed is perturbed) causes mixing of the fluid. Shown on the movie are small tracer particles within the flow illustrating the mixing. The experiments on the left provide validation. Ambient fluid capture: The following slide shows how, using the control of eddies within flow, particles or reagents can be trapped. Autocatalytic reaction: This slide illustrates a simple autocatalytic scheme within the same geometry. Its possible to build a series of reactions into these models to couple flow and kinetics. 2 Phase droplet: An illustration of a 2-phase simulation similar to that found within a microemulsion device. This sort of method can be used to optimise geometric and flow conditions for robust droplet formation. The group also has considerable experience in experiments in this area (2-phase flow).

21 2-Phase droplet simulation Flow Chemistry

22 Continuous Process for Hydrothermal Synthesis of Photocatalytic Nanomaterials University of Leeds Prof XZ Wang University College London, Dr J Darr Process Scale-up: PAT and Multi-scale Modeling H 2 P1 P2 Several metal salts in solution H R C F B PID Water Solar energy Photocatalysts Hydrogen xygen Ti 2 Zn Sn 2 Nano size < 100 nm Hydrothermal synthesis SCW Metal feed AUX Feed > 2 2 million

23 Reactor Design for Solvent Free Synthesis of Nanomaterials Feed S1 H Feed S2 H NH2 H glycol chitosan NH2 n R1 H N H H NH2 H H x N CH 3 I y Inert gas fixed bed: no; fluidised bed: yes R2 Feed S4 Product S5 H H Jet-mixed tank R2 H H + N H 3C CH3 CH3 u NH2 H H v N w Feed S1 Feed S2 S3 R2 Feed S4 quaternary ammonium palmitoyl glycol chitosan (GCPQ) R1 or Product S5 S3 Feed S4 Inert gas Product S3 R2 Product S5 Impinging-jet R2 Mixture of glycol chitosan (GC), sodium bicarbonate dissolved in water Feed S1 Feed S2 Palmitic acid N- hydroxysuccinimide S4: Methyl iodide, sodium hydroxide & sodium iodide in water, or betaine, sodium bicarbonate, water, N-(3-Dimethylaminopropyl)-N - ethylcarbodiimide hydrochloride Reactor R1 S3 Feed S4 Reactor R2 S3: Palmitoyl glycol chiltosan; unreacted GC,water,sodium bicarbonate Product S5 Feed S1 Inert gas fixed bed: no; fluidised bed: yes Feed S2 Filter Product S3 Packed bed Gas Minimum fluidisation Fluidised bed Gas

24 scc 2 Flow Chemistry (Chris Rayner) Extensive expertise in reactions in sc 2 Unique solvent, inexpensive, easy disposal and no solvent residues Mostly done in batch in Leeds Excellent understanding of likely problems (solubility, reactivity, high pressure) scc 2 (or liquid C 2 ) flow methods in reactions, product isolation and purification. E.g. stripping and/or recycling of dipolar aprotic solvents (DMF) Crystallisation and drying

25 SCW xidation of rganics (Paul Williams) Supercritical water oxidation very efficient for destruction of organics (T c 374 ºC, P c 221 bar) Extensive experience in supercritical water technology (mainly batch) Continuous SCW system to be commissioned shortly (Mojtaba Ghadiri/Yulong Ding) Current projects include SCW oxidation of organic wastes SCW gasification of food wastes

26 Continuous reactions and purification (iprd) Coupling reaction chemistry to product purification Batch or continuous reactions Batch or continuous purification methods (e.g. crystallisation) Interdependence of purification and reaction chemistry Improve reproducibility and quality of process and product Extensive experience is all relevant areas

27 Points for discussion Comments and suggestions on project portfolio Identification of interested partners to form consortia for collaboration, application or information exchange