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RE: Any method other than distillation?



Chris Nicolaus (Christovoru.Nicolaus@upm-kymmene.com)asked, in part:

> Do you guys know any method other than distillation in segregating
> chemicals?

There are a number of separations methods covered in any basic chemical
engineering text, selection of which depends upon a variety of factors
including relative concentrations, relative volatility,
freezing/crystalization temperatures, steric considerations (size/shape of
the molecules) and relative solubility in a third solvent, or differences in
interaction with an adsorbent. 

It is of course possible to separate chemicals via distillation even when
their b.p.'s are very similar, but it tends to be more energy intensive,
requires more trays in the column, etc.

If you can provide more specifics about the compounds it might be easier to
steer you in the right direction.  If not, consider membrane separation or
possibly a change in solvent phase to a solvent that is further from the
catalyst vis-a-vis b.p.  Quite often, process chemistry is selected on the
basis direct scale-up of laboratory synthesis, with little consideration
being given to how practical the solvent is once production scale is
reached.   It is often worth re-examining the solvent selection rather than
assuming it is a fixed part of the synthesis.

Good luck!

Scott Butner (scott.butner@pnl.gov) 
Director, ChemAlliance
Senior Research Scientist, Data & Knowledge Engineering Group
Pacific Northwest National Laboratory
MSIN K7-28
PO Box 999, Richland, WA  99352
(509)-372-4946 voice/(509)-375-2443 fax
ChemAlliance: http://www.chemalliance.org/



> -----Original Message-----
> From: Christovoru.Nicolaus@upm-kymmene.com
> [mailto:Christovoru.Nicolaus@upm-kymmene.com]
> Sent: Monday, June 17, 2002 11:52 AM
> To: p2tech@great-lakes.net
> Subject: Any method other than distillation?
> 
> 
> Hi all,
> 
> Do you guys know any method other than distillation in segregating
> chemicals?
> 
> My situation is that the solvent and catalyst boiling points 
> are in the
> same range, could you segregate it? How? Thanks.
> 
> chris
> 
> 
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