Dear Martin

The following paper can help you

Mild Temperature Oxidation of Phenol over Rare Earth Exchanged Aluminum Pillared Montmorillonites

http://www.ijer.ir/?_action=article&keywords=bet

All the Best

thanks, we use N2 as adsorbate but we work with natural soils, I think it is a bit different comparing with your model system

 thanks anyway for the answer

   all the best

Of course! 

Based on my experience, 105°c for 24 hours is enough for degasing. After that you can measure the BET. The most important thing that you should not exceed 105 otherwise you will lose the organic matter which is one of the most important content of the soil

For soils, water is the main molecule you are evacuating, so 105ºC in inert-gas flow or 60ºC in high vacuum should be enough, for 12-24 h. However, you can make a thermogravimmetric analysis in N2 atmosphere to explore the thermal stability of organics and materials your are interested in.

thanks to all of you, you have been helpful