One-Pot Preparation of Methyl N-Phenyl Carbamate and Zn(OAc)2/SiO2 Catalyst with Enhanced Stability

The one-pot preparation of methyl N-phenyl carbamate (MPC) and supported Zn(OAc)(2)/SiO2-OP was investigated. Zn(OAc)(2) and SiO2 were added to the reaction between dimethyl carbonate (DMC) and aniline upon which MPC and Zn(OAc)(2)/SiO2-OP were obtained simultaneously. The co-prepared Zn(OAc)(2)/SiO2-OP showed superior catalytic performance for MPC synthesis, giving a aniline conversion of 96.3% and a MPC selectivity of 99.7%. Compared with catalyst prepared by incipient impregnation, Zn(OAc)(2)/SiO2-OP was more stable during the reaction, and the aniline conversion was 85.0% with MPC selectivity of 88.2% for the seventh time. The catalyst was characterized and the results suggested that Zn(OAc)(2), Zn-5(OH)(8)(OAc)(2).2H(2)O, ZnO and Zn4O(OAc)(6) are present on SiO2 surface. Zn(OAc)(2) and Zn4O(OAc)(6) are the active sites for MPC synthesis. The superior stability of the Zn(OAc)(2)/SiO2-OP catalyst came from the presence of Zn4O(OAc)(6).