Lab sized LPG mercaptan removal problem

[PetroBob]

I am installing a small (lab sized) steam methane reformer which will run on bottled LPG. Unfortunately where we're located there isn't a mercaptan-free LPG supply. So we'll need to remove ethyl mercaptans & tert-butyl mercaptans so as not to poison the reformer catalyst. I'm looking for ideas as to how to take the mercaptans out. We’ve been looking at various options, some kind of zeolite removal system or some kind of gas sweetening catalyst (like this

http://www.chemicalproductsokc.com/PERCO.html).

Part of the problem is how to get rid of the sulphur even after we’ve stripped it – our lab is in a city so it’s not possible to discharge even very low flow rate of sulphur containing gases. We only have a small budget (compared with oil industry!). I'd welcome any ideas & suggestions regarding low flow rate mercaptan removal.

 

[Jason5000]

SMR units usually have a guard bed in the front end to protect the reforming catalyst from sulfur in the feed. The company I work for usually gets the stuff from Johnson Matthey or Haldor Topsoe.

You can extract mercaptan from LPG pretty effectively with 20 Baume caustic. Without a regen system for the caustic you'll have to run it as batch treater. So you'll have spent caustic to deal with, but if your flow rates and mercaptan removal are low enough it may be manageable.

 

[moltenmetal]

Out of curiosity, where did you get that "lab scale SMR" that you're installing?

 

[dcasto]

Zinc Oxide should do the job, thats what we use as a gaurd bed material.

 

[PetroBob]

Folks, many thanks for the replies. We will investigate the caustic option. Moltenmetal, we haven't been able to find a cost effective lab sized reformer (since we have some specific and non-standard requirements). At this stage we are investigating building our own unit from scratch. However if anyone knows of a supplier who makes H2 generators for low flowrate (eg 10 to 50 litres/minute) please post details.

 

[RogerH]

Petrobob
Why not pay a visit to e.g. Johnson-Mathew or Haldor Topsoe. They have pilot plants in various sizes and might help you to overcome practical problems effectively.
Did see pilots in HTAS (Denmark) for SMR catalyst testing. If that fits your objective remains to be seen.
Good luck

 

[moltenmetal]

If what you need is hydrogen rather than syngas, electrolysis is the way to do it. Stuart Energy Systems, which I believe was eaten by Hydrogenics, would be a good bet.

If you're after a pilot syngas generator rather than just hydrogen, one of the licensors/catalyst companies (Haldor Topsoe, Johnson Matthey, Air Products etc.) or a pilot plant company (

http://www.zeton.com)

would be good bets. But there's a lot to this, if your end goal is the hydrogen rather than having your own hydrogen generation technology. Even though people have been making reformers for 80 years, they don't give these things away in Cracker Jack boxes.

If capital is what you're worried about, and it's a short-term use, tube trailers may be your best bet- talk to Air Products.

If you must go it on your own, methanol is a far better choice than LPG- you can reform it at very low temperatures.

 

[Chance17]

I would suggest using activated carbon

 

[soma0324]

it is quite a complicated problem. few years back i have worked on a full scale industrial unit for mercaptins removal from C3+ mix. every method you pick have some limitations at the end which you have to deal with. i have looked into installing the moleculare sieves from UOP. they offer a clean solution to this problem but still you have to get rid of regeneration gas containing all the mercaptins and sulfur. JM Catalysts have if i believe a prodcut for hydrolysis. but remember whatever you remove you need to get rid of it one way or other. if it is a small scale project i would recommend looking into batch time system e.g. cautic wash etc. if you have ways to get rid of caustic. MISWACO i think also offer some kind of solid product for this purpose. but the time i was working in it they were just doing the lab testing and couldnt provide me any real data. so we rejected that option. you may want to look into it. also it depends on how tight are you looking for the specs on your LPG. If you want to bring the total elemental sulfur content down to zero it may be a bit of difficult task.
in summary there are several options available. it all depends how you want to deal with this problem and how much you can pay for that. i hope this will help.
Regards,