Can zeolite serve double duty?

[GNBrews]

Can you use 3A zeolite molecular sieves as efficient column packing? I realize that the water adsorption capacity would be fairly quickly depleted, but wouldn't the small beads covered in microscopic texture also offer a huge surface are for HETP, even saturated? I know a lot of folks are using expanded clay pebbles or lava rock. Just a shower thought.

[Corsaire]

A quick look on wikipedia (never heard of the stuff so had to look it up) reveals it's made of aluminium... which is a no go.
Further it may contain traces of asbestos...

[Kareltje]

I looked it up too.
Don't know if it can be used as asked, but it is not made of aluminium, it contains aluminium. Just like clay, for instance.
It is widely used, among others to clean water in ponds or aquaria. Or to clean the human body of stuff; detoxing they call it.

[still_stirrin]

Zeolites are “micro porous” structures. The pores are so small that the structures can separate ions from each other, as used in ion exchange beds such as water softeners. The pores hold the ions in the zeolite structures until flushed out during the recharge cycle.

Also, zeolites are used in petrochemical processes because of their ability to catalyze separation of the many hydrocarbons. They can also enhance the boiling process if saturated in a solution by significantly increase the exposed surface of the fluid to the applied heat.

So, zeolites have many purposes in chemical and thermodynamic physics. In theory, they could help separate the molecules in a vapor stream along the column in a distillation process. However, the very nature of the micro porosity would cause a significant pressure differential along the path in order to get the (now separated) molecules to move. It would, however, allow heat of rising vapors to transfer to the falling condensate in the reflux exchange within the micro structures. In other words, they would “plug the column” with vapor and condensate and you wouldn’t see condensate advance to the product condenser.

Similarly, lava rock, a very effective column packing, performs just like zeolite in the heat transfer from vapors to condensate, however with much larger pores. The structure is “cavernous” when compared to zeolites, however, such that molecules aren’t held in the pores and the reflux can separate constituents and the flow continue.

Zeolites do pose an interesting opportunity for our hobby. It is just that the reflux process would require significant pressures to push the vapors through the zeolite packed column. The required operating conditions would make it very dangerous (explosively) for simple hobbiests to undertake.

Better to simply get some lava rocks instead.
ss