US EPA

7457656 

Journal Article 

One-step synthesis of methyl N-phenyl carbamate from aniline, urea and methanol over γ-Al2O3 

Dou, LY; An, HL; Li, Q; Wang, GR; Zhao, XQ; Wang, YJ 

2013 

27 

6 

1004-1011 

Chinese 

10.3969/j.issn.1003-9015.2013.06.014 

Methyl N-phenyl carbamate (MPC) is a key intermediate for the manufacture of methylene diphenyl diisocyanate (MDI) by non-phosgene method, and one-step synthesis of MPC from aniline(AN), urea and methanol is a green technology. In this paper, the catalytic performance of metal oxides and Lewis acid in the reaction of MPC synthesis was evaluated at first and it was found that the γ-Al2O3 calcined at 400°C for 2 h presents the best catalytic activity. Under the suitable reaction conditions of initial pressure of 0.6 MPa, reaction temperature of 180°C, reaction time of 2 h, and n(AN):n(γ-Al2O3):n(Urea):n(MeOH) = 1:0.12:5:75, the conversion of aniline and the selectivity of MPC are 88.4% and 84.6%, respectively. Additionally, γ-Al2O3 could be reused five times without significant deactivation, which indicates that it has satisfactory stability in this reaction. Studies on the catalytic mechanism reveal that the reaction proceeds mainly along the process of forming the methyl carbamate (MC) as intermediate, and the reaction mechanism for MPC synthesis was proposed. 

γ-Al2O3; Aniline; Methanol; Methyl N-phenyl carbamate; Urea; Catalytic mechanisms; Catalytic performance; Methyl N-phenyl carbamate; Methylene diphenyl diisocyanate; Non-phosgene method; One step synthesis; Reaction conditions; Reaction temperature; Aluminum; Aniline; Catalyst activity; Metabolism; Methanol; Model predictive control; Synthesis (chemical); Urea; Reaction intermediates