Removing Trace oxygen from Argon
Misra Ashutosh
I am trying to remove trace amounts of oxygen from argon for use in an
experiment. I have tried using traps (cooled by liq. N2 ) containing
molecular seives but it doesnt help. The pressure of the system is around
2 Torr.
Does anyone have an idea as to how trace oxygen is removed from gases?
Many thanks in advance
jrw
Pack a quartz or Vycor tube with copper wool. Put the tube in a tube furnace
that can heat it to 600C and pass the argon thru it. The copper should
tarnish. The copper can be regenerated by passing (CAREFULLY) hydrogen thru
it. We used to do this to purge the oxygen from nitrogen in a UV spectrometer
to get below 200 nm.
Karl Loren Houseknecht
Oxygen is usually scrubbed out using oxygen scavenging
transition metals supported on some kind of inert material. I
kind of doubt you would be able to trap it with liqid N2 unless
your flow rate was low and your surface area on the trap was
huge.
Baxter sells disposable oxygen traps that contain supported
metal scavengers on them (ranging from $44 to $94) depending on
volume. Check page 1085 in the 94-95 catalog (part #s
G5301-1-through-4)
--
| Karl L. Houseknecht kl...@virginia.edu |
| Department of Chemistry "Now that you've eaten chicken |
| University of Virginia stuffed with sage, you get to |
| (804)-924-7046 listen to a sage stuffed with |
Joe Warmus
Try a supported Cu catalyst (BTS ot Ridox). You get this stuff (BASF I
think) and reduce it by heating to 70°C and passing a mixture of Ar and H2
through it. It turns from green to black as it is reduced. I've used this
setup for years to do O2 sensitive organic synthesis and it works great.
For more details see a Book called "The manipulation of air sensitive
compounds" by Shriver and Drezdzon (Wiley) or talk to an inorganic or
organometallic chemist about stting one up.
--
Joe Warmus
The purpose of training is to tighten up the slack, toughen the body, and polish the spirit.--O'Sensei
(The opinions expressed are entirely my own and do not reflect those of Parke-Davis)
Tadeusz Bak
[...]
>Does anyone have an idea as to how trace oxygen is removed from gases?
>Many thanks in advance
You can let pass argon through a heated (about 250C) pipe filled with
copper ribbon. It is also possible to use iron (to obtain smaller partial
pressure of oxygen) but the temparature of the pipe must be higher.
--
Tadeusz
Iain L J Patterson
> I am trying to remove trace amounts of oxygen from argon for use in an
> experiment. I have tried using traps (cooled by liq. N2 ) containing
> molecular seives but it doesnt help. The pressure of the system is around
> 2 Torr.
> Does anyone have an idea as to how trace oxygen is removed from gases?
> Many thanks in advance
We always used a scrubber column containing chromium(II) oxide on silica-gel,
although the prep. is a bit frightening (adsorb CrO3 solution on fine silica-
gel, oven dry, pack a glass column with it, flush with N2 or Ar at a high
temperature to thoroughly dry the column, reduce it with CO in a tube furnace
at just the right temperature, flush with N2 or Ar until cool, transport to gas
line without exposure to air). The work involved various metal alkyls, and all
traces of oxygen and moisture had to be removed from the system. The sky-blue
colour of the active column changes to brown as it becomes exhausted, and a
sharp boundary is usually maintained. You should take off the column and
regenerate it while there is still a couple of inches of blue column left.
The column is extremely sensitive to air: I once had a leaky valve which let a
rush of air into a fresh column - the packing immediately turned dark brown and
glowed red hot.
If you still want to try one, mail me for the details.
Cheers,
Iain.
Paul M. Momita
On our schlenk lines we use two scrubbers. One is for water and is
just a column filled with Molecular sieves. The other is Ridox, a
commercially available (Fisher?) O2 scrubber. This works very well
with N2 and Ar inert gasses.
Ernest S. Tomlinson
text, _Experiments in Organic Chemistry_ (I think that's it.) A procedure
for the removal of trace oxygen from _nitrogen_ is given--I seem to remem-
ber that it involves the use of the sodium ketyl radical anion from benzo-
phenone. At any rate, Fieser gives an explicit laboratory procedure, and
doubtless a literature reference or two.
-et
--
Ernest Tomlinson | "I pause; I think about the past in the gloom/
e-mail: e...@ugcs.caltech.edu | the smell of gasoline permeates the room/every-
-----------------------------+ one has a little secret he keeps/I light the
| fires while the city sleeps" - MC 900 ft Jesus, _The City Sleeps_
Stanley A. Orrell
most welding and gas supply houses. They claim to remove 15 ppm O2 down to
ppb range on one pass. They are renewable, and are filled I think with
DOW Q-5 reactant. Relatively cheap too.
Joe Bellina
film since it would getter the oxygen but not the Ar. Actually, just about
any metal film would work...but the lifetime might be short depending on
the oxygen partial pressure. You will form a monolayer...ie saturation in
about 1 sec if the partial pressure is e-6 torr. The times scale inversely
with the pressure.
In article <sorrell.778485400@somnet>, sor...@somnet.sandia.gov (Stanley
A. Orrell) wrote:
--
Joseph Bellina (jbel...@saintmarys.edu)
Saint Mary's College, Notre Dame, IN 46556