What is Flow Chemistry?
A wide range of intensified continuous flow processing solutions, developed over the past years, have proven to be more efficient, more environmentally friendly, and more cost effective than conventional batch manufacture. Flow chemistry in combination with several other enabling technologies, such as additive manufacturing, photochemistry, high pressure processing or electrochemistry, provides the chemical industry with a toolbox of new manufacturing solutions capable of transforming the industry by radically improving existing chemical processes and enabling the manufacture of previously inaccessible materials.
A good example is to think about the manufacture of pharmaceuticals. For every kilogram of fine chemicals that the pharmaceutical industry currently produces, 5–100 times that amount of chemical waste is generated. For industry it’s a waste of resources and money.
It doesn’t have to be that way.
Flow chemistry offers advantages over traditional batch chemistry:
- Better process control resulting in higher product yields & purities, shorter reaction times, and less waste
- Better scalability due to compact, efficient and modular reactor design
- Smaller physical footprint resulting in reduced capital, operating & maintenance costs
- Superior inherent safety resulting in lower risk and environmental impact
- Superior mixing, enhanced heat and mass transfer, wide pressure and temperature operation windows
- ‘Plug and Play’ modular equipment; lower capital investment
What does this look like practically?
The following is an example of six step liner sequence that we transferred from batch to a continuous flow process.
| Reaction Step | Batch | Flow | Waste | Batch | Flow | ||
| Yield | PMI* | Yield | PMI* | ||||
| 1 | 85% | 119.36 | 98% | 6.57 | Chlorinated waste | 218 L | 0 L |
| 2 | Non-chlorinated waste | 612 L | 74 L | ||||
| 3 | 70% | 173.22 | 85% | 18.5 | Contaminated aqueous waste | 418 L | 33 L |
| 4 | 85% | 119.36 | 98% | 5.16 | |||
| 5 | 76% | 54.94 | 81% | 31.35 | Liquid waste total (in litres) | 1,248 | 106 |
| 6 | 75% | 63.85 | 71% | 11.28 | Energy total (in kWh) | 18.5 | 1.6 |
* PMI – Process Mass Intensity is the amount of material required (reagents, solvents, etc in kg) to produce 1kg of product
** Aust. J. Chem., 2012, 66, 172–177, doi:10.1071/CH12435