Chloride Removal Alternatives

[sshep]

We wish to feed a byproduct liquid hydrocarbon (paraffins and aromatics boiling in the decane-dodecane range) containing up to 20ppm organic (and possibly some inorganic) chlorides to a downstream process which can be poisoned by chlorides. Chloride spec is <1ppm per licensor in the downstream process, but we have always been non-detectible in the feed to that process in the past.

What sort of treatment alternatives are available for my stream? Flow is <5gpm.

Any help appreciated. Best wishes, sshep

 

[epoisses]

My best bet would be an adsorbant bed, try Rohm and Haas or equivalent to see what they can do. Put the bed where the highest concentration is. Do you know where they come from in the first place, is it the reformer?

 

[liberoSimulation]

I guess that stream comes out from ethylene plant that is the pyrolysis gasoline sent to BTX plant.
If you can give the source of this Cl as epoisses asked, I would help.

Cheers

 

[sshep]

Thanks for your interest. These are ppm levels of chloro-paraffins, chloro-benzene and heavier aromatics, and perhaps residual HCl as by-products of a chloride based chemical process for making linear alkylbenzene. My previous experience has been to use an alumina bed to scavange any inorganic halogens (we use HF in some of our other processes), but that the ability of such a bed to clean-up organic chlorides is less well known.

The downstream process will include a light hydrotreating which may breakdown these chlorides, but introduces uncertainties related to the HCl produced. Any chlorides making it through that step will poison the downstream process, so we wish to remove chlorides upstream as much as possible.

As a fixed bed is probably the most economical treatment for such a small flow and chloride load, I will gladly take any further recommendations on vendors and/or bed material. If other alternatives are available then please bring them to my attention as well. In any case thanks and best wishes, sshep

p.s. you will note that I didn't want to rely on hydrotreating these chlorinated compounds, but if we did, are there any bad interactions between HCl and H2S, NH3 which could cause problems in that process, or would it be a straight HCl corrosion issue.

 

[epoisses]

Yes you will certainly want to avoid hydrotreating these beasts, fully agree with the reasons you quote. I have some experience with an ion exchange resin, but not sure to what extent that would take out organic chlorides. I'd contact a vendor, ask some samples and do a few lab tests to see if you can get down to insignicant Cl levels at all at least at lab scale, then take it from there. Good luck!

 

[Yordif]

For a time I worked for the catalyst division of ICI, which is now Johnson Matthey Catalysts. We used both Alumina and Mixed Metal oxide adsorbents to remove CL but that was generally HCl. Organics are largely untouched by what I had, but that was 7 years ago. The metal oxide technology maybe much better now. You might try their web site for a local representative.

I would recomend against the alumina as it has enough acidity to actually cause some organic chloride formation in the right enviroment.

 

[liberoSimulation]

You can check activated alumina produced by Alcan Chem. Group as they are very attractive and have been found economical solutions in some applications.
In my MS thesis, I used this adsorbent to removing phosphates ions from wastewater and it has been found that this adsorbent is highly recommended.
If I remember well, this adsorbent has good ion exchange with Cl ions after OH and PO4 ions.

Hope this would give help to you

Cheers