Mellitic acid production by ruthenium ion-catalyzed oxidation of cokes

Abstract

Cokes are rich in highly condensed aromatic rings, however, the current applications of cokes mainly focus on the thermal energy or carbon-rich structures, and the aromatic ring structures in cokes are underutilized, which are usually employed as feedstock to fabricate valuable fine chemicals and synthesized with complex steps. The pyrolysis temperatures have great impact on the structures of resulting cokes. It is necessary to learn about the structural features of cokes produced from different pyrolysis conditions to explore the optimal reaction conditions. This study reported an eco-friendly and efficient method, ruthenium ion-catalyzed oxidation, to utilize Guizhou cokes produced from different pyrolysis temperatures for green and value-added chemical production. The results indicate that arenecarboxylic acids account for more than 90% of all the oxidation products, in which mellitic acid could be up to more than 70%. Compared with previous studies, this is the highest mellitic acid yield achieved in the oxidation products of fossil resources, indicating that cokes show good performance for the clean production of mellitic acid. The ruthenium ion-catalyzed oxidation product distribution demonstrates that 1,200 °C is a turning point during coking of Guizhou coals and the structure and reactivity of Guizhou coke1,200 deviate from the expected variation tendency, which is related to the inverse influence of pyrolysis temperatures on condensation degree and ash property of cokes. Effect of pyrolysis temperatures on aromatic structures and reactivity of Guizhou cokes was also discussed further.