Adjusting the Porosity of Coal-Based Activated Carbons Based on a Catalytic Physical Activation Process for Gas and Liquid Adsorption

Porous carbons have been widely explored and utilized in the fields of adsorption. Pore structure design is the key for achieving high-capacity and fast adsorption. Herein, we develop a simple and general method for pore regulation of coal-based activated carbons (ACs), which is based on a catalytic physical activation process by using the inherent minerals in coal precursor. By adjusting the inherent mineral distribution in the coal precursors, activated carbons with various pore configurations including microporous structure and hierarchically porous structure can be obtained. More specifically, ZD-HCF-AC from a mineral-free coal precursor shows a microporous structure with a low surface area of 345 m2 g–1, while ZD-AC from mineral-rich coal exhibits a hierarchically porous structure with remarkably improved surface area of 933 m2 g–1. Ca and Mg components in the minerals notably promote the development of mesopore and macropores and lead to the resulting ACs with hierarchical pore structure. The effect of inherent minerals is not only limited to Zhundong coal but also available to other mineral-rich coals. Evaluated as adsorbents, microporous ZD-HCF-AC exhibits excellent SO2 adsorption capacities up to 73.4 mg·g–1; hierarchically porous ZD-AC has the best performance for Rhodamine B (RhB) adsorption with capacity up to 227.8 mg·g–1. This work not only provides a simple and scalable method for preparing coal-based activated carbons for various adsorption applications but also offers a new route for adjusting the porosity of activated carbons during the physical activation process.