Catalytic mechanism of Na on coal pyrolysis-derived carbon black formation: Experiment and DFT simulation.

Coal-derived carbon black is the main composition of PM 2.5 , used in the rubber industry and energy storage fields. The formation and structure control of carbon black have attracted significant attention. Alkali metals have influence on the dynamic formation of coal-derived carbon black. To analyze the mechanism of Na in the formation of carbon black, a high-temperature drop tube furnace was used to analysis of carbon black from the pyrolysis of acid-washed coal and Na-containing coal at 1250 °C. DFT was applied to simulate the stepwise inhibitory effect of Na on the polymerization of PAHs into carbon black. The results show that Na promotes the oxidative cracking of large PAHs into small PAHs during the formation of coal-derived carbon black (reaction energy barrier is reduced by 17.7%), and inhibits the condensation of small PAHs molecules to form carbon black molecules (reaction energy barrier is increased by 74.7%), which causes the length of carbon black is shortened by 14.3%, and its curvature is increased by 1.7%. Na could change the spatial structure of formed carbon black-graphite crystallites, which increases the spacing of carbon black by approximately 6.2% to 16.3%. Na enhances the electrochemical performance of carbon black by 2 to 3 times. [Display omitted] • Experimental and DFT study of the catalytic effect of Na on carbon black. • Na promotes oxidation of PAHs and fracture of carbon black crystallites. • Na inhibits the polymerization of PAHs into carbon black particles. • Na changes carbon black structure, increasing the spacing by 6.2% ~ 16.3%. • The electrochemical performance of carbon black is enhanced 2–3 times by Na. [ABSTRACT FROM AUTHOR]