Hydrochar material can be chemically activated using KOH to synthesis of porous carbon materials.
During this, the mixture (of hydrochar and KOH) can be heat-treated between 450 - 800 degree Celsius (heating rate: 3 0C min-1) under a nitrogen gas flow and held at this temperature for 1 h ( the parameters may depend on the raw material for the hydrochar).
In my understanding, nitrogen gas flow uses to expel the oxygen which is found in the furnace during the process.
My question is: assume that we don't have nitrogen gas flow.......
Can the mixture (of hydrochar and KOH) heat-treated in a closed batch reactor with out nitrogen gas flow?
In my opinion, there is no oxygen inside the closed batch reactor so we don't need to use nitrogen gas flow. I mean, the hydrochar will not change to ash.
Can you help please to elaborate this issue?
If you have no sweep gas, you will re-condense a fair portion of the devolatilizing material into your char, which will not accomplish your desired pore opening. Our group, and many in the literature, have found that you need at least 100 mL/min flow of inert gas to affect the necessary mass transfer to carry off volatiles. As an example, see: Işıtan, Seçil, Selim Ceylan, Yıldıray Topcu, Chloe Hintz, Juliann Tefft, Thiago Chellappa, Jicheng Guo, and Jillian L. Goldfarb. "Product quality optimization in an integrated biorefinery: Conversion of pistachio nutshell biomass to biofuels and activated biochars via pyrolysis." Energy Conversion and Management 127 (2016): 576-588.
In line with the question but on a different case, should the flow of nitrogen be stopped or continued during cool down of a tube furnace, specifically after activation at the desired elevated temperature has been completed?
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