Synergistic Effect of FeCl₃ on Pore-Structure and Crystallization of Zhundong Coal-based Activated Carbons

In the preparing processes of porous carbon, the development of porous structure was highly related to the evolution of graphitic crystalline structure. Meanwhile, the porous structure will be collapse as the crystallinity increases. Development of porous with both high surface area and graphitization degree has attracted considerable research attention in the fields of gas adsorption and electrochemical energy storage. With the assistant of CO₂ atmosphere, porous carbons can be one-step synthesized by using the FeCl₃·6H₂O and low-cost Chinese Zhundong coal as the metal and carbon precursor, respectively. As a result, with the increase of FeCl₃ addition, the surface area increased from 346 m²·g^-1 to 574 m²·g^-1. Besides, the graphitization degree improved simultaneously with I_G/I_All increasing from 8.774% to 9.328%. Through the analysis, CO₂ can be in situ generated by using iron oxides derived from the hydrolysis-pyrolysis of FeCl₃-6H₂0 and CO from the pyrolysis-activation processes, and etch the carbon-based coal framework to create micropore. Fe₃C could be generated by the reaction between amorphous carbon and reductant Fe. Accompanied by the carbon dissolution-precipitation procedure, graphitization degree has be improved. Meanwhile, some mesopore could be released in pickling process. In general, FeCl₃ was template and activation agent, and has catalytic effect of graphitization.