A Carbon‐Based Solid Acid Catalyst Prepared through a One‐Step Hydrothermal Carbonization: Efficient Catalysts for Liquid‐Phase Nitrification

Abstract Carbon‐based solid acid catalysts were successfully prepared by hydrothermal carbonization method and one‐pot method using naphthalene crosslinked by formaldehyde and sulfonated by H 2 SO 4 (98 %). The characterization results showed that the catalysts prepared by hydrothermal carbonization method had more amorphous carbon composed of aromatic carbon sheets with functional groups (−SO 3 H, −COOH and −OH) than the catalyst prepared by one‐pot method. The preparation conditions of hydrothermal carbonization method were optimized. The F−N−SO 3 H‐h‐2.49 (1 : 11) prepared under optimal conditions showed high conversion of cyclohexane (48.2 %) and selectivity to nitrocyclohexan (98.2 %) at 125 °C for liquid‐phase nitrification, attributed to high acid site density (3.08 mmol/g) and amorphous carbon structure with hydrophilic functional groups. The F−N−SO 3 H‐h‐2.49 (1 : 11) also showed excellent thermal stability until 460 °C. The thermal stability of the catalyst is due to mutual electron‐withdrawal of aromatic carbon sheets.