Dear all,

We are building a conventional fluorination line, and now testing the
conversion chamber by introducing an aliquot of pure oxygen tank gas into
our system, while heating a graphite rod up to 650-700°C. The furnace
consists of a couple of IR lamps focussed on a graphite rod contained in a
quartz tube (external heating), and the temperature of the graphite is
checked by a thermocouple inserted inside the graphite. While heating the
graphite and cooling down an U tube in a liquid nitrogen trap,  we
introduce the oxygen in the previously pumped conversion chamber; at that
moment what we should observe is first an increase of the pressure, as O2
is introduced,  and then a progressive drop while the CO2 is condensed. We
just see the O2 introduction and no CO2 seems to be trapped. We can't find
out what is wrong.Two possible causes come to my mind :
- we just form CO, but why?
- the graphite quality we got is not compatible with an oxidation process?
I am quite puzzled, as I used a similar device, not exactely the same but
quite similar in principle in NIGL, few years ago, but it was no problem as
Peter Greenwood and other friends there could attest. The major recognized
difference about the quality of the graphite is that the one I bought here
in France is far denser than the one currently used in UK; furthermore the
shape of the graphite is different as we needed plane surfaces for the IR
lamps heating....but I can't see any other major differences.

If anybody can be of some help? Should I try another type of graphite?
Which one? All ideas are really welcome, as we are quite novice in the
business.

Cheers
Marie

PS Sorry I mixed to addresses, so I send it again

* * * * * * * * * * * * * * * * * * * * * * * * *
*       Dr. Marie - Christine  GERBE            *
* Departement de Geologie- Petrologie           *
* Université Jean Monnet                        *
* UMR CNRS 6524 "Magmas et volcans"             *
* 23 rue du Dr. Paul Michelon                   *
* F-42023 Saint-Etienne cedex 02 - France       *
* tel. 04 77 42 18 23 - Fax. 04 77 42 18 08     *
* From foreign countries:                       *
* tel. 33 4 77 42 18 23 - Fax 33 4 77 42 18 08  *
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