Dear Paul and others,

I looked to find the composition of the catalyst, but the only description
given on internet (found the provider/manufacturer of SOFNOCAT easily by
Google) is a precious metal material, and nothing else. Suppose it is
impossible to get more info on the composition for manufaiurers reasons.

There are two ways to convert CO into CO2:
2CO + O2 = 2CO2 [1]
2CO = CO2 + C [2]

Since no oxygen is part of the catalyst material, as I understood,
conversion of CO into CO2 only can occur by reaction [2], meaning a carbon
stays behind at the surface of the catalyst for each molecule of CO2 formed.
This also can be an explanation for becoming less effective in time - there
is simply less surface of catalyst at which the reaction is taking place.
Restoring, eventually can be done by oxydising gently the carbon on the
catalysts surface, if not leading to oxidation of the catalyst itself or
sintering of the catalyst grains and thus reducing the catalytic surface
where the reaction can take place. And sintering may be another reason of
decrease in catalyst active surface during the conversion process, if
occuring at the applied temperature at all. Further, I am wondering if
traces of halogens in your sample gas might effect (pollute) the catalyst,
but that is just a suggestion and probably, if happening at all, just a
minor effect compared by the first.

Another point for this conversion [2] is to consider the effect on the
C-isotopic composition? Ideally all oxygen is recovered but C is lost and
certainly will introduce isotopic fractionation (how large depends on the
conversion temperature; you did not mention that, but I guess a couple of
hundred degrees). So, if only oxygen is your interest it will not introduce
fractionation, but if also the carbon is of interest you will have a
problem.

Hope this helps,
Best wishes,
Pier.
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> List members,
>
> We have been using SOFNOCAT catalyst in a sample prep line to remove CO
> (converts it to CO2). We've noticed that it can become less effective over
> time. Baking at 100C seems to help, but I am hoping that others might have
> some tips on how to regenerate this catalyst. Anyone?
>
> Paul Eby
>
> [log in to unmask]
> Biogeochemistry Lab (E-Hut, room 102)
> School of Earth and Ocean Science
> University of Victoria
>
> PO Box 3055
> Victoria, B.C.
> Canada
> V8W 3P6
>
> phone: 250-721-6183
> fax: 250-472-4620
>