SF6 to SO2

Here is a bunch of papers on this, but many of them involve high temperatures, corona discharge, etc.: http://www.google.com/search?q=sf6+oxidation&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=

Efectively your hint is very interesting, thank you very much.

ANTONIO CONDE

You should be very cautious of eliminate water and metals in your probe, this substances catalize (I do not know the mechanism) the formation of SO2 (ppm), most the SO2 forms in the intercristal metalic cavities, remember SF6 is spheric and very small, take care during analysis, dont use glass syringes, use sampling loops made of teflon.

Thank you Tornado and Antonio for your comments. The sensor has stainless steel tubes and although the gas is mostly dry, it is not completely dry so there might be few 100s ppm of water vapour mixed with the sample. It would be useful to know more about the formation of SO2 from SF6 in these conditions and what I can do to reduce it. Is there any pointers to information or material to help me do that. Unfortunately Chemistry is not my cup of tea! - I am an electronics design engineer, so I am limited to how deep I can get into that. Also, I have to have the stainless steel tubes for other reasons, although I might be able to get them coated somehow if it gets desperate! Many Thanks

Thank you Morrie for the link. It looks like that I am doing something wrong, as I am getting an error message saying "TOO MANY CONSTRAINTS". Say I am drawing a sample from a bottle that contains 50%SF6 balance N2 but could have impurities of 100ppm H2O, 400ppm CF4. The gas is originally at 8bar pressure and the pressure is reduced down close to ambient using a pressure regulator before entering the instrument. I have set the starting temperature at 20 oC, starting pressure at 8bar, equilibrium pressure at 1 atm. I have set the constraints as constant volume and temperature. I have selected the elements to be S, F, H, O and C and the composition as SF6:0.5, N2:0.4995, CF4:0.0004 and H2O:0.0001. I get the above error! How many mistakes can you spot there? p.s I have already admitted my limited knowledge in Chemistry! Many Thanks

You need to know the reaction products. It seems that perhaps there are not sufficient species in the data set for this reaction. This paper describes a lot more species than I would have imagined. It is for a higher temperature range than you are interested in, but it might be helpful.

http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=AD0842407

Morrie, I can't download this paper. Do you have a copy that you can send me? or do you have any suggestions to what data I should enter into the Chemical Equilibrium Calculation to explore what could be happening in the example that I have described?