Synthesis of MDI from Dimethyl Carbonate over Solid Catalysts
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- 作者：Xinqiang Zhao ; Yanji Wang ; Shufang Wang ; Hongjian Yang ; and Jiyan Zhang
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2002
- 出版时间：October 16, 2002
- 年：2002
- 卷：41
- 期：21
- 页码：5139 - 5144
- 全文大小：149K
- 年卷期：v.41,no.21(October 16, 2002)
- ISSN：1520-5045
文摘
The catalytic synthesis of methylene diphenyl-4,4'-diisocyanate (MDI) consists of three steps.Starting from the catalytic reaction of aniline and dimethyl carbonate (DMC), methyl phenylcarbamate (MPC) is formed. Then MPC condenses with formaldehyde to produce dimethylmethylene diphenyl-4,4'-dicarbamate (MDC). Last, MDC is decomposed to MDI. For the firststep, the properties of supported zinc acetate catalysts on different supports have been examined.Supported zinc acetate catalyst on activated carbon (AC) or 
-Al2O3 shows good catalyticproperties. Over Zn(OAc)2/AC catalyst, MPC yield reaches 78% and the selectivity is 98%. Forthe second step, when zinc chloride is used as a catalyst and nitrobenzene as a solvent, MDCyield can reach 87.4%. The catalytic activity of AC-supported ZnCl2 catalyst, which is calculatedbased on 1 mol of ZnCl2, is much higher than that of homogeneous ZnCl2. For the third step,zinc powder and its organic salts show higher catalytic activity; MDI yield is 87.3% over zincpowder catalyst.
-Al2O3 shows good catalyticproperties. Over Zn(OAc)2/AC catalyst, MPC yield reaches 78% and the selectivity is 98%. Forthe second step, when zinc chloride is used as a catalyst and nitrobenzene as a solvent, MDCyield can reach 87.4%. The catalytic activity of AC-supported ZnCl2 catalyst, which is calculatedbased on 1 mol of ZnCl2, is much higher than that of homogeneous ZnCl2. For the third step,zinc powder and its organic salts show higher catalytic activity; MDI yield is 87.3% over zincpowder catalyst.