The biomass was pre-heated. Small steel containers of ~30g capacity were used. Thereafter, the containers were filled almost up to their brim and wrapped with Aluminium foil to further limit the oxygen.
Am I going wrong somewhere?
Dear Swati. By producing biochar, you do a kind of offline pyrolysis. This produces a lot of organic compounds and a lot of these will be in the gass phase at 300°C. If you have the vials full, there is only very little space so that a very high pressure will be the result. If you want to produce char, you may consider heating your sample in a through flow system (e.g. a pyrolysis oven) so that you can to vent your sample during heating with any gas mixture you like. The advantage is that you have much more control over the atmospheric conditions at normal pressure.
Hi Swati,
The autogenous pressure will continue to increase if there is no escape for volatiles generated during the decomposition of biomass leading to the situation you encountered. Reducing the sample loading (around 5g or less, if possible) could be helpful.
BTW, the quantity and quality/properties of biochar produced under high pressure could be different compared to those produced from conventional pyrolysis due to increased secondary reactions.
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