关键词: Pt/&gamma, -Al₂O₃催化剂, 辛可尼定修饰, 固定床反应器, 丙酮酸乙酯, 多相不对称加氢

Abstract: The enantioselective hydrogenation of ethyl pyruvate on the cinchonidine modified Pt/Al₂O₃catalyst was investigated using a high pressure reaction system with a fixed bed reactor for the purpose to produce the chiral product without separating the catalyst from the reaction system.The reaction was also investigated in a batch reactor for comparison.About 60% e.e. and90% e.e. were obtained with the fixed bed reactor and the batch reactor respectively, demonstrating the possibility for the heterogeneous asymmetric hydrogenation in the fixed bed reactor.Some adsorbed chiral modifier, cinchonidine, can be slowly removed from the surface of Pt/Al₂O₃under the continuous flow reaction, as a result, the e.e. values drops with the reaction time in the fixed bed reactor.The enantio selectivity is higher in the fixed bed reactor, but lower in the batch reactor when ethanol was used as solvent than that when acetic acid as solvent.COwas used as molecular probe to characterize the adsorption of cinchonidine on the catalyst surface by IRspectroscopy.Ared shift observed in IRspectra of coadsorbed COwith cinchonidine suggests that the cinchonidine adsorption is mainly through the π interaction with platinum surface and donating electron to the platinum surface.

Key words: Pt/ γ-Al₂O₃catalyst, Cinchonidine modifier, Fixed bed reactor, Ethyl pyruvate, Heterogeneous asymmetric hydrogenation.