摘要
二苯甲烷二氨基甲酸甲酯(MDC)是生产二苯甲烷二异氰酸酯(MDI)的重要中间体。针对尿素法合成MDC选择性低的问题,首先分别对氨基甲酸甲酯(MC)路径和4-氨基-4'-脲基二苯甲烷(AUM)路径进行了热力学分析,结果表明,AUM路径相对较容易进行。采用间歇排氨的操作方式,考察了反应条件对二苯甲烷二胺(MDA)、尿素和甲醇合成MDC反应的影响,确定出适宜的反应条件为:反应温度180℃,反应初压1.2 MPa,n(MDA):n(尿素)∶n(甲醇)∶n(γ-Al_2O_3)=1∶5∶50∶0.1。在此条件下,MDA转化率为94.2%,MDC收率和选择性分别为41.2%和43.7%,MDC和4-氨基-4′-氨基甲酸甲酯二苯甲烷(MMC)的联合选择性为81.6%,比封闭体系分别高出12.5%、14.9%、11.5%和4.6%。
Methylene diphenyl dicarbamate（MDC）is a key intermediate for the manufacture of methylene diphenyl diisocyanate（MDI）.In order to increase the selectivity to MDC in the urea route to MDC synthesis,the reaction for the synthesis of MDC separately via methyl carbamate（MC）pathway and 4-amino-4′-ureido diphenyl methane（AUM）pathway were thermodynamically analyzed.The result showed that the reaction pathway via AUM was thermodynamically easier than MC pathway.The influence of reaction conditions on MDC synthesis from methylene dianiline（MDA）,urea and methanol was studied with releasing NH_3 from the system during the reaction process.Under the suitable conditions of reaction temperature of 180 ℃,initial pressure of 1.2 MPa,n（MDA）∶n（urea）∶n（methanol）∶n（γ-Al2O3）=1∶5∶50∶0.1,the conversion of MDA was 94.2%,the yield and selectivity of MDC was 41.2%and 43.7%,and the united selectivity of MDC and methyl 4[（4′-aminophenyl）methylene]phenylcarbamate（MMC）was 81.6%,which was improved separately by 12.5%,14.9%,11.5% and 4.6% compared to the closed system.
出处
《精细石油化工》
CAS
CSCD
北大核心
2016年第2期71-76,共6页
Speciality Petrochemicals
基金
国家自然科学基金项目(21476058)
河北省应用基础研究计划重点基础研究项目(12965642D)
