VP · Technology
Vapor Permeation
Vapor permeation runs the same kind of dense, non-porous membrane as pervaporation, but on a vapor-phase feed, and the permeate leaves as a vapor too. Compared with pervaporation, selectivity is higher and flux is lower, and because the membrane touches vapor rather than liquid it avoids swelling and concentration polarization. It suits feeds that are already vapor, such as the top product of a fractionating column, where only the reflux has to be condensed.
What it solves
Performance you can size against.
What the process delivers. Every number is testable on your own feed.
- Higher selectivity than pervaporation
- Vapor feeds give higher selectivity than liquid feeds, at the cost of lower flux.
- Longer membrane life
- The membrane contacts vapor, not liquid, so it does not swell and concentration polarization stays low.
- Compatible with existing process
- No need to condense and re-vaporize the feed, and vapor permeation retrofits into existing processes.
How it works
The working principle.
A vapor feed is fed across the membrane at low pressure. The target component sorbs into the dense membrane and diffuses across. A vacuum or chilled sweep on the permeate side condenses the recovered fraction. Non-permeating components return to process or vent.
Performance envelope
Specs and operating range.
For preliminary sizing only. Production sizing is always validated against your specific feed.
- Feed phase
- Saturated vapor, or vapor and gas mixture
- Permeate phase
- Vapor
- Membrane
- Dense, non-porous
- Transport
- Sorption, diffusion, desorption
- Selectivity vs pervaporation
- Higher, with lower flux
How we compare
VP vs the alternatives.
Where Vapor Permeation wins, where it does not, and where the alternatives are honestly the better fit.
| Trait | Vapor Permeation | Pervaporation | Activated Carbon Recovery |
|---|---|---|---|
| Feed phase | Vapor (taps directly into vapor lines) | Liquid (requires liquid feed) | Either, but vapor preferred |
| Flux | Lower than pervaporation | Higher than vapor permeation | N/A (batch capture, not flux) |
| Continuous operation | Yes | Yes | No (load and regenerate cycles) |
| Best fit | Column-overhead vapor and other vapor-phase solvent streams | Liquid solvent dehydration, azeotrope breaking | Low-volume, intermittent VOC streams |
Feed phase
Vapor Permeation
Vapor (taps directly into vapor lines)
Pervaporation
Liquid (requires liquid feed)
Activated Carbon Recovery
Either, but vapor preferred
Flux
Vapor Permeation
Lower than pervaporation
Pervaporation
Higher than vapor permeation
Activated Carbon Recovery
N/A (batch capture, not flux)
Continuous operation
Vapor Permeation
Yes
Pervaporation
Yes
Activated Carbon Recovery
No (load and regenerate cycles)
Best fit
Vapor Permeation
Column-overhead vapor and other vapor-phase solvent streams
Pervaporation
Liquid solvent dehydration, azeotrope breaking
Activated Carbon Recovery
Low-volume, intermittent VOC streams
Where this technology applies
Industries that use this process.
Vapor Permeation fits some sectors better than others.
Engineering FAQ
Questions engineers ask.
The questions we hear weekly. If you have a different one, send it with your consultation request and we will answer it directly.
When should I use vapor permeation over pervaporation?
Can vapor permeation be combined with pervaporation?
Have a feed that VP
might fit?
We will pilot before we promise. Send us a sample and a target outcome. If the technology fits, we will tell you what to expect; if it does not, we will tell you that too.