Process intensification aims to make chemical plants dramatically smaller, safer and more efficient. Microreactors embody this: reactions run in channels of micrometre-to-millimetre scale. The tiny dimensions give an enormous surface-area-to-volume ratio, transforming heat and mass transfer and enabling precise, continuous control.
Working principle
Because channels are small, the diffusion distance is short and mixing is near-instant, while the large wall area removes or supplies heat extremely fast. This lets engineers run fast, highly exothermic or hazardous reactions safely — there is very little reactive material present at any instant. Operating in continuous flow rather than batch gives consistent product quality and easy automation.
| Property | Batch (stirred tank) | Microreactor |
|---|---|---|
| Heat transfer | Limited | Excellent (high area/vol) |
| Mixing | Slow, scale-dependent | Near-instant |
| Safety | Large reactive inventory | Tiny inventory |
| Scale-up | Re-engineer vessel | Numbering-up (parallel units) |
| Mode | Batch | Continuous |
Key insightScale-up is by ‘numbering-up’ — running many identical reactors in parallel — which avoids the classical scale-up uncertainty of redesigning a bigger vessel. Fouling and clogging of fine channels are the main practical risks.
Applications
- Pharmaceutical and fine-chemical continuous synthesis
- Safe handling of hazardous or highly exothermic reactions
- On-demand, distributed (point-of-use) chemical production
References & further reading
- Hessel et al., “Novel Process Windows – Concept, Proposition and Evaluation,” Chem. Eng. Technol., 2009.
- Jensen, “Flow Chemistry — Microreaction Technology Comes of Age,” AIChE Journal, 2017.
- Stankiewicz & Moulijn, “Process Intensification: Transforming Chemical Engineering,” Chem. Eng. Progress, 2000.