Wood based activated charcoal powder (2 ~ 20 μm) was subjected to heat treatment at 850℃ for 4 hours under a nitrogen atmosphere. After cooling down to room temperature, remove from the furnace. After encountering air, activated carbon powder undergoes spontaneous combustion.
What is the cause of this? How can it be avoided?
P.S. I am very sure that when taking out the activated carbon from the high temperature furnace, the activated carbon has already cooled completely.
Fuxin Liu
The reason for the spontaneous combustion of activated carbon is a decrease in the activation energy of the reaction with oxygen, the replacement of nitrogen with air. To reduce spontaneous combustion, you can reduce the oxygen content in the air using a vacuum. For example, keep activated carbon in a vacuum desiccator. To increase the activation energy, it can be kept in a desiccator over calcium carbonate.
Keep already heated carbon in Nitrogen atmosphere or in vacuum. There is no other solution. After heating there is strong exothermic reaction of the oxygen in normal atmosphere. For sure is good to cool the sample to control temperature.
Thank you Mr. Mirgorod. Our experiment was based on large-scale industrial production, and the economic benefits of storing samples in a low-oxygen environment were not good. Your explanation about activation energy has given us inspiration. Thank you again for enlightening. @Yuri Mirgorod
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