Insight into synthesis of graphitized activated carbons with high oxidation resistance for gas adsorption

Oxidation resistance is a critical factor restricting the industrial application of activated carbons (ACs). To address this issue, we propose a two-step activation–carbonization strategy to prepare graphitized ACs with high porosity and oxidation resistance. The activation process achieved a well-developed pore structure, while the subsequent carbonization process facilitated high-temperature pyrolysis and catalytic graphitization, leading to short-range microcrystalline reorganization and functional groups decomposition. Among the tested catalysts, Ni exhibited the strongest catalytic effect on graphitization, significantly enhancing both the graphitization degree and microcrystalline size of ACs compared to Fe and Co. Interestingly, the decomposition of functional groups and the growth of microcrystalline are major strategies for the increase in oxidation resistance of ACs, where the average microcrystalline size is linearly correlated with the oxidative activation energy. Owing to low content of functional groups and high graphitization degree, the loss of toluene adsorption capacity decreased from 16.5 % to 4.3 % in the humid environment, and the isosteric heat of CO₂ adsorption decreased. This work not only develops an effective strategy for improving oxidation resistance of ACs but also provides valuable insights for their industrial applications in gas adsorption.