Tdep
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Using 3A Molecular Sieves to dry gases
Is it possible to use molecular sieves to dry gasses like chlorine and ammonia? It would be useful to me if possible. I need some dry gasses, and
passing large amounts of wet gas through a chemical drying agent tends to start to clump and clog up the line. I know I can get around that in some
ways but the thought of using a column of sieves seems simple.
Can ammonia and chlorine stick in the pores of the sieves? Chlorine seems rather big, but ammonia seems small enough. But even more in general, if you
had a big molecule, could you dry the gas stream of it with 3A sieves? It seems like obviously you can, but I can't find any note of it online really,
so am I missing something?
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Aqua-regia
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I think this were A wrong way. Molecularsieves working slow, and concepted for liquid.
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Sulaiman
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oxygen concentrators use 5A or 13X zeolites/sieves to absorb nitrogen in preference to oxygen,
in the gas phase.
CAUTION : Hobby Chemist, not Professional or even Amateur
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Nicodem
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Thread Moved
8-12-2016 at 11:39 |
Dan Vizine
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Molecular sieves are not designed for such uses.
Chlorine is best dried by bubbling through concentrated H2SO4. As with most all amines, ammonia is best preliminarily dried over sodium or potassium
hydroxide. Final drying usually involves sodium metal, if it must be rigorous.
"All Your Children Are Poor Unfortunate Victims of Lies You Believe, a Plague Upon Your Ignorance that Keeps the Youth from the Truth They
Deserve"...F. Zappa
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BromicAcid
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Yes, they could be used that way but that is not a traditional use for sieves. I have used them successfully to dry nitrogen that most would have
already considered 'dry'. My initial worry was that they dry somewhat slowly compared to standard drying agents for gases. However, on reflection I
cannot say that is truly the case. To test our sieves would would take a standard weight of sieves and pour in a set amount of water and swirl and
look at the heat of the 'reaction' to see if they were fresh enough, the heat evolution was very fast and exothermic so I suppose the hydration is
somewhat fast.
Quote: Originally posted by Dan Vizine  | | As with most all amines, ammonia is best preliminarily dried over sodium or potassium hydroxide. Final drying usually involves sodium metal, if it
must be rigorous. |
Although not the best method of preparation, ammonia does react with sodium at room temp to produce the amide.
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Dan Vizine
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| Quote: Originally posted by BromicAcid | Yes, they could be used that way but that is not a traditional use for sieves. I have used them successfully to dry nitrogen that most would have
already considered 'dry'. My initial worry was that they dry somewhat slowly compared to standard drying agents for gases. However, on reflection I
cannot say that is truly the case. To test our sieves would would take a standard weight of sieves and pour in a set amount of water and swirl and
look at the heat of the 'reaction' to see if they were fresh enough, the heat evolution was very fast and exothermic so I suppose the hydration is
somewhat fast.
| Quote: Originally posted by Dan Vizine | | As with most all amines, ammonia is best preliminarily dried over sodium or potassium hydroxide. Final drying usually involves sodium metal, if it
must be rigorous. |
Although not the best method of preparation, ammonia does react with sodium at room temp to produce the amide. |
You think molecular sieves will handle wet chlorine? Nitrogen is one thing, chlorine another.
We use sieves to dry our glovebox atmospheres to sub-ppm levels, so, yes, they can obviously dry gasses.
Sodium, or it's [final] product, sodamide, is exactly how ammonia is dried:
http://www.worldofchemicals.com/chemicals/chemical-propertie...
"It is the reagent of choice for the drying of ammonia and is also widely used as a strong base in organic chemistry, often in liquid ammonia
solution"
[Edited on 13-12-2016 by Dan Vizine]
"All Your Children Are Poor Unfortunate Victims of Lies You Believe, a Plague Upon Your Ignorance that Keeps the Youth from the Truth They
Deserve"...F. Zappa
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