苯氨基甲酸甲酯(MPC)是非光气法合成二苯甲烷二异氰酸酯的重要中间体。以苯胺、CO2和甲醇为原料催化合成MPC是一条绿色的工艺路线。为此重点研究了制备条件对Cu-Fe/Zr O2-Si O2催化性能的影响以及反应条件对MPC合成反应的影响。结果表明,采用机械混合法制备的金属负载量为10%(按氧化物计)的Cu-Fe/Zr O2-Si O2对MPC合成反应具有较好的催化效果。对不同方法制备的催化剂进行了H2-TPR实验测定,发现催化剂表面的金属活性位越多,金属与载体之间的作用越强,催化剂的活性越好。适宜的MPC合成反应条件为:溶剂乙腈/苯胺体积比为2:1,甲醇/苯胺摩尔比为1.2:1,催化剂用量为13%(wt),CO2初压为2.0 MPa,反应温度为180℃和反应时间为11 h。在此条件下,苯胺的转化率为14.0%,MPC的收率及其选择性分别为9.2%及65.7%,远高于目前文献值。
Methyl N-phenyl carbamate (MPC) is an important intermediate for the manufacture of methylene diphenyl diisoeyanate (MDI) via non-phosgene routes. A novel green process for the synthesis of MPC using aniline, carbon dioxide and methanol was studied, and the effects of preparation conditions on catalytic performance of Cu-Fe/ZrO2-SiO2 together with reaction condition effects on MPC synthesis was emphasized. The results indicate that Cu-Fe/ZrO2-SiO2 prepared by mechanical mixing with metal loading of 10%(wt) has better catalytic performance. H2-TPR results demonstrate that more metal active sites and stronger interaction between metal and support can result in better catalytic performance. The optimized reaction conditions were as follows: volume ratio of acetonitrile : aniline =2:1, molar ratio of methanol : aniline = 1.2:1, catalyst weight percentage =13%, CO2 initial pressure = 2.0 MPa, reaction temperature = 180~C, and reaction time = 11 h. The conversion of aniline, the yield and selectivity of MPC were 14%, 9.2% and 65.7%, respectively, which are much higher than the values reported.