An Overview of Flow Chemistry
What is (Continuous) Flow in Chemistry?
Continuous flow chemistry allows the chemical reactions required for production to occur as a continuously flowing stream, with a constant stream of starting materials entering a flow reactor at the same rate that a constant stream of products leaves the flow reactor.
Flow reactors employ flow chemistry principles to provide continuous chemical manufacturing capabilities to a variety of production industries including pharmaceutical and chemical, operating at "steady-state" to produce material continuously and indefinitely without interruption. It is this continuous production at "steady-state" that is the main differentiator between flow technology and batch production, the other widely used method of chemical production.
The flow chemistry reaction pathways used in flow reactors are typically tube-like in design and are manufactured from non-reactive materials such as Hastelloy or silicon carbide. The mixing methods in flow reactors can include diffusion alone, passive (or static) mixing and, more recently, active mixing (also described as dynamic mixing).
Why is Flow Chemistry Important?
Continuous flow technology is important because it brings versatility, productivity and efficiency to chemical manufacturing by enabling precise control over important reaction parameters such as heat transfer (heating and cooling), mixing (and mass-transfer) as well as reaction time (residence time).
Such a level of control brings with it better potential outcomes of reaction processes, including percentage yields, purities and selectivities, whilst providing low capital costs, small reactor footprints, efficient energy use, reduced solvent use, low emissions and improved safety management.
Additionally, the concept of operating at a period of steady-state, as is the case with flow reactors, typically reduces the number of operator interventions required in a chemical production plant compared to batch-wise production.
Advantages of Flow Chemistry
There are well-defined key advantages to using flow technologies as compared to standard batch chemistry methods:
Improved heat transfer
Improved mass transfer/mixing
Easier route to scale-up
In-line downstream processing
Improved Safety (managing hazardous reagents and intermediates)
Smaller reactor footprint
Lower operational expenditure or running costs
Lower fugitive emissions
Lower solvent use and waste
Many of the benefits of continuous flow technology also address the principles of green chemistry. Flow chemistry delivers more sustainable and safer chemical processes, further details can be found in our recent article in the Chemical Industry Journal.
Advantages of Batch Chemistry
Versatile; a batch reactor can be easily adapted to handle many different processes and campaigns.
Productive; large amounts of material can be produced with each batch.
Established; batch technology is well known within the chemical industry and a vast number of the process have been designed and used in batch.
However, batch processing proceeds much more slowly and as such the overall cost of processing increases by comparison with flow chemistry. Start-up and shut-down processes of batch equipment can increase energy consumption and waste material, and the quality discrepancy between batches can be significant. This can lead to lost production and compromised quality if the batch process isn’t monitored closely.
Flow chemistry has one main disadvantage, which is that overall, batch processing remains the standard within the fine chemical and pharmaceutical industries, simply because versatility, productivity and established know-how are extremely desirable attributes when considering a route to chemical manufacture. Despite the many additional advantages and efficiencies of flow chemistry over batch.
Flow technologies that embrace and build upon versatility and productivity will open up the possibility for their widespread use within the chemical industries. This is the motivation and rationale for the design of our range of Coflore flow reactors from AM Technology.
The range can be used independently for proof of concepts or our continuous flow technology can be used to build production scale skids, transitioning a batch process into an end-to-end continuous process. Check out how flow chemistry is used to build a process skid below!
What are the Different Types of Flow Chemistry Reactors?
There are a number of types of reactors in flow chemistry, including plug flow reactors and continuous stirred tank reactors. Delve deeper into how continuous flow technology works by looking at the various types of flow chemistry reactors:
Useful External Links
Flow Chemistry (organic-chemistry.org)