>Where can I find background information on platinum as a catalyst for the
>oxygen-CO2 conversion. Most of the new papers dealing with fluorination
>of oxides and subsequent O2-CO2 conversion refer to this step but without
>details. Are there any other catalysts to promote the high-temperature
>formation of CO2 (res. to avoid the CO-formation)?
The O2-CO2 conversion step using hot graphite, as anyone will tell you, is
a can of worms and was at the root of many of the problems on our old
fluorination line. The standard technique is to use chloroplatinic acid
solution to 'platinise' the graphite rod but we ended up using an electric
platinum tea bag (made of perforated Pt foil) into which we added granules
of graphite as it was used up. We found that platinising the graphite did
not help particularly but pre-combusting (10 mins at 1000oC in air) helped
to activate the surface to give more consistent results.
We have long since abandoned converting O2 to CO2 and run O2 gas on the
Optima without any problems at all. Quantitative transfer of small
quantities of O2 can be performed using silica gel cold fingers. I would
never go back to O2- CO2 conversion!
Geology Department, Royal Holloway College, University of London, Egham
Hill, Egham, Surrey TW20 0EX
Tel: 01784 443587 Office
443637 Isotope lab (Prism)
443629 Isotope lab (Optima)