摘要
苯氨基甲酸甲酯(MPC)是非光气合成MDI的重要中间体,苯胺(AN)、尿素和甲醇一步合成MPC是一条绿色的反应工艺。首先考察了部分金属氧化物和Lewis酸对该反应的催化性能,发现经400℃焙烧2 h的γ-Al2O3催化活性最好。其次,确定了γ-Al2O3催化合成MPC的适宜反应条件:n(AN):n(γ-Al2O3):n(Urea):n(MeOH)=1:0.12:5:75,初压0.6 MPa,反应温度180℃,反应时间2 h。在此条件下,苯胺转化率为88.4%,MPC选择性为84.6%。在此基础上,考察了γ-Al2O3的催化稳定性,发现重复使用五次后,其催化性能没有明显的下降。最后,对γ-Al2O3的催化机理进行了研究,发现γ-Al2O3催化苯胺、尿素和甲醇一步合成MPC反应主要沿着以氨基甲酸甲酯为中间产物的路径进行。并据此提出了催化反应机理。
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-A1203 calcined at 400℃ for 2 h presents the best catalytic activity. Under the suitable reaction conditions of initial pressure of 0.6 MPa, reaction temperature of 180℃, reaction time of 2 h, and n（AN）：n（γ-A1203）：n（Urea）：n（MeOH）=l：0.12：5：75, the conversion of aniline and the selectivity of MPC are 88.4% and 84.6%, respectively. Additionally, γ-A1203 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.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2013年第6期1004-1011,共8页
Journal of Chemical Engineering of Chinese Universities
基金
国家自然科学基金项目(20976035)
河北省自然科学基金项目(B2010000019)
天津市自然科学基金项目(12JCYBJC12800)
河北省应用基础研究计划重点基础研究项目(12965642D)
