Influence of K on coal-based carbon black formation from naphthalene pyrolysis in a drop tube reactor

Coal-based carbon black is an important rubber reinforcing filler, and its preparation raw material is coal tar, which is the primary pyrolysis product of coal. The metals in coal and coal tar have a significant impact on the formation of carbon black. Utilizing metals to regulate the physical and chemical properties of coal-based carbon black has become a new research direction. Using naphthalene as a model compound, the influence of alkali metal potassium on the formation of coal-based carbon black was studied in a high-temperature drop tube furnace under an inert atmosphere. The changes in the carbon black yield before and after the addition of potassium salts were analyzed, and the physical and chemical properties of the carbon black were characterized. The results show that the three potassium salts significantly inhibit the growth of coal-based carbon black, reducing the particle size of the carbon black by 18–30 %. The order of the inhibitory effect is: CH₃COOK > KCl > K₂CO₃. In addition, potassium promotes the dehydrogenation process of aromatic hydrocarbons, reduces the degree of order of carbon black, inhibits the graphitization process of carbon black, and suppresses the oxidation process by preventing the conversion of C-O to C[dbnd]O. This study elucidates the mechanism of the influence of potassium on the formation of coal-based carbon black, analyzes its impact on reinforcing performance, and provides important insights for the directional regulation of coal-based carbon black.