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Clean synthesis of methyl N‐phenyl carbamate over ZnO‐TiO 2 catalyst
Author(s) -
Li Fang,
Wang Yanji,
Xue Wei,
Zhao Xinqiang
Publication year - 2009
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.2003
Subject(s) - catalysis , aniline , calcination , lewis acids and bases , selectivity , dimethyl carbonate , chemistry , carbamate , inorganic chemistry , monomer , nuclear chemistry , materials science , organic chemistry , polymer
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‐TiO 2 , was prepared for MPC synthesis. ZnO‐TiO 2 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‐TiO 2 exhibits better catalytic activity than ZnO or TiO 2 alone, which may result from the formation of ZnTiO 3 and Zn 2 TiO 4 . Compared with ZnTiO 3 , Zn 2 TiO 4 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. Copyright © 2008 Society of Chemical Industry