Clean synthesis of methyl N-phenyl carbamate over ZnO-TiO₂ catalyst
2009
Li, Fang | Wang, Yanji | Xue, Wei | Zhao, Xinqiang
BACKGROUND: Methyl N-phenyl carbamate (MPC) is an intermediate for the preparation of methylene diphenyl diisocyanate (MDI), which is an important monomer for polyurethane synthesis. The synthesis of MPC by the reaction of aniline and dimethyl carbonate (DMC) is becoming more and more attractive. However, most of the catalysts used in MPC synthesis are homogeneous and not environment-friendly. Therefore, it is important and necessary to develop a new kind of oxide catalyst, that is not only friendly to the environment, but also exhibits higher activity and longer service time.RESULTS: A new heterogeneous catalyst, ZnO-TiO₂, was prepared for MPC synthesis. ZnO-TiO₂ catalyst with a molar ratio Ti/Zn = 2 and calcined at 673 K exhibited good catalytic activity: aniline conversion was 96.9% and MPC yield 66.7%.CONCLUSION: ZnO-TiO₂ exhibits better catalytic activity than ZnO or TiO₂ alone, which may result from the formation of ZnTiO₃ and Zn₂TiO₄. Compared with ZnTiO₃, Zn₂TiO₄ has better selectivity for MPC synthesis. Lewis acid sites with weaker acid strength favour MPC synthesis. The catalyst activity can be recovered almost completely by calcination.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by National Agricultural Library