Introduction To The Scale Up Of Continuous Microwave Flow Chemistry

Yvonne Wharton

C-Tech History
1966
Electricity Council Research Center (ECRC) established as a publiclyfunded research institute1990
ECRC privatised along with the UK energy generation industry,
becomes EA Technology
2000
Management buyout of EA Technology’s Energy Division, whichbecomes C-Tech Innovation

Approach➡ Concept

chemistry, physics, metallurgy➡ Pilotmechanical & electrical➡ Trialsdesign & build➡ Production

commissioning

Advanced Thermal Technologies• Continuous Flow Chemistry• Microwave Calcining• Food and Drink Processing• Continuous Cooking• Advanced Induction Heating• RF Curing and Moulding• Plasma Surface Modification

C-Tech Innovation
Challenges of Scaling Up Microwave Chemistry

Microwave Chemistry Scale Up at C-Tech
Case Studies
Large Production Scale Microwave Chemistry

Challenges of Scale Up
100

Power80
60
40
2000

5

101520DistanceModerately absorbing

Strongly absorbing

Penetration depth

Penetration Depth = Distance through the object being heated where theincident power drops to 1/e of that at the surface

25Challenges of Scale Up•Penetration depth and uniformity•Materials•Measurement and control

Microwave Cavity

Quartz process tube

Travelling wave
applicator

Microwave
sourcePressure and microwave
containmentWHY: Microwave Flow Chemistry
FasterFaster reaction times

Cleaner

Rapid heating and absence of wall effects results in less side
reactionsGreener

Cleaner reactions means less purification/solvents/SMs. Energy
saving MW flow vs batch

Safer

Less inventory of hazardous materials

Pilot Scale Reactor• Flow rates up to 400 mL/min• Dual feed vessels• Pressurised receiver vessel• Designed to process up to 20 L in a single run (can be operated for longer periods)• Homogeneous reactions• Light heterogeneous reactions

Equipment Specification
FeaturesMicrowave power - 1-6 kW as standard (higher if required) Temperature
range - ambient to 250°C

Pressure - ambient to 30 bar
Flow rate - 5 mL to 1 L/min
Materials of construction - glass, fluoropolymer, stainless steel
Automatic temperature control

Options
Fibre optic temperature measurement
Halide resistant coating of steel parts
Complete plant or bare reactor

Case Studies

Reaction from Robinson Brothers
Equilibrium reaction - requires removal of aldehyde by-product to drive the reaction forward
Takes 4.5 days to produce 500kg, 30 batches per campaign
30 year old reaction

Case Studies

Reaction done in MW flow reactor
Temperatures between 120-150°CReaction times 2-10 mins
Gave >75% conversation to product and shows much less disulfide impurity
than standard reaction
Difficulties in separating product from excess DMAPA used in the reaction
Currently investigating reduction of DMAPA eqvs and non aliphatic amines

Case Studies
11RRRXRNH 2• Difficult nucleophillic amination reaction – using conventional heating• Reaction parameters quickly defined by MW chemistry - MW lab method gives double
the yield with less solvent and readily available reagents• Following day 18 L processed in 3.5 h to give 2.6 kg• No method development required for scale up – saved an estimated 4 weeks inproject timeCase Studies
Pd
Pd//C
C,,KO
KOA
Ac
DMF/H2O•

Thermal reaction• 92% conversion to product after 2h•

MW reaction• 295 mL/min (~1 min residence time)• Reaction went to 98% completion (analysis by GC/MS)• 4.08 kg/h of product•Reaction run in pilot scale reactor in Sweden• Continuous operation –- 32 hours• 140 L of reaction mixture giving 22 kg of isolated productCase Studies
Yb(O(OTTf)3
EtOH, AcOH•

Thermal reaction• 35% conversion after 8 h•

MW reaction• Reaction run at 75 mL/min (~4 min residence time)• 71% conversion to product• 307 g/h of productCase Studies•MW flow chemistry allows direct scale up from lab scale to plant scale

without time consuming process development step
•MW flow chemistry allows rapid heating of solvents (sometimes above theirboiling point)•Higher yields•Shorter reaction times•Less side products

C-Wave - Continuous Microwave Flow Reactors• Temperature up to 250°C• Pressure up to 20 bar• Flow rates up to 200 mL/min• Dual feed vessels• Dual receiver vessels• Designed to process up to 10 L in a single run(can be operated for longer periods)• Homogeneous reactions Light heterogeneousreactions• Temperature up to 180°C• Pressure up to 20 bar• 0.22L capacity• 6kW

C-Wave - Continuous Microwave Flow Reactors
20 bar, 215°C
20 mL capacity
1 kW, 2450 MHz
Hastelloy and quartz glass

ATEX rated
450 W solid state generator@2450 MHz20 bar
2 x 10 L pressurised receiver vessels
17 mL/min, 30 sec residence time
From 0 - 180°C in a single pass

Scale Up•Scale up to 2000 kg/h throughput•Maintain reaction temperature for 5.5 mins
•Requires 120 kW•Designed as 4 separate modules with independent pumping, MWpower
supplies and MW power control

Scale UpScale UpScale UpScale Up• Continuous flow microwave generator in 4 modular sections• 5 x 6kW microwave generators @ 2450 MHz in each module section• 20mm inside diameter quartz glass reactor tube with >1000mm heat application
length• Holding section with 5.5 minutes residence time at required flow rate
• Automatic control of outlet temperature, easy to use touch screen facility.
Manual control option for microwave power also available, power can be set
from 10% to 100%
• Working temperature up to 230°C• Working pressure up to 10 bar• Pressure relief and leak detection system• Temperature and power analogue outputs• Data logging of all process data of up to 50 data points with 20,000 entries eachConclusions
Large scale microwave chemistry is possible
Its already being done at pilot scaleContinuous flow not batch
Materials and mechanical design are as important as microwave cavity design
Benefits
Faster reactions, more throughput
Cleaner - no hot oil, no fouling of hot surfaces

Greener - higher yields, less by-products, less catalyst, less waste
Safer - lower chemical inventories, easy temperature control
High throughput and continuous operation
Handles liquids and light slurries

Excellent chemical resistanceC-Tech Innovation Ltd
Capenhurst Technology Park
Chester, CH1 6EH0151 347 2900
info@ctechinnovation.com
www.ctechinnovation.com