Synthesis of methyl N-phenyl carbamate from phenyl urea and methanol over the KF/Al₂O₃ catalyst

The solid alkaline catalysts of supported potassium halides were prepared by impregnation method and used in the methanolysis of phenyl urea with methanol to synthesize methyl N-phenyl carbamate (MPC); the influence of oxide supports and potassium halides on the catalyst performance was investigated. The results indicated that KF/Al₂O₃ exhibits high catalytic activity and selectivity to MPC; the KF/Al₂O₃ catalyst containing 50% KF and calcined at 500 ℃ for 4 h performs best in the methanolysis of phenyl urea, over which the conversion of phenyl urea and selectivity to MPC reach 96.5% and 86.3%, respectively. The XRD results proved that KF and Al₂O₃ are partially transformed to K₃AlF₆ due to the strong interaction between KF and Al₂O₃. Both KF and K₃AlF₆ are active for the activation of methanol and selective conversion of phenyl urea; the excellent performance of KF/Al₂O₃ catalyst in the methanolysis of phenyl urea to MPC can be ascribed to the synergy of KF and K₃AlF₆.