Alumina-carbon Composites Prepared By Resorcinol/Phloroglucinol-formaldehyde Resin And Its Application In Asymmetric Hydrogenation

Ethyl(R)-2-hydroxy-4-phenylbutyrate obtained by asymmetric hydrogenation of ethyl 2-oxo-4-phenylbutyrate(EOPB)is a key intermediate in the process of synthetising perindopril.As perindopril is one of the primary antihypertensive agents in the market today,how to synthesize(R)-EHPB efficiently and economically is the focus of research.Nowadays,the most widely used catalyst in the asymmetric hydrogenation of EOPB is the commercial Pt/Al2O3.Commercial Pt/Al2O3 performs a high conversion rate and optical selectivity in the asymmertic hydrogenation,but the reusability of the catalyst is poor and the performance of the catalyst would have a sharp decline after using several times.In this thesis,we used the high activity resorcinol-formaldehyde or phloroglucinol-formaldehyde as carbon source to synthesize alumina-carbon composite materials by the chelating co-assembly method.The preparation of alumina-carbon composites and the asymmetric hydrogenation performance of supported Pt catalysts had already been systematically studied.Combining the characterization and catalytic properties of alumina-carbon composites and catalysts,the following main results were obtained:(1)The method of preparing alumina-carbon composites by chelating co-assembly was simpler and more convenient with the active resorcinol-formaldehyde resin as carbon source.By characterizing the composite,it was found that the alumina was uniformly distributed inside the composite material,and the carbon presented predominantly in a disordered state.By nitrogen adsorption-desorption and XRD analysis,it was found that the composites had high specific surface area and was highly ordered.(2)The catalyst Pt/Al@RFC-0.6 prepared by the impregnation method could obtained 98.9% conversion and 82.3% optical selectivity in the asymmetric hydrogenation.The catalytic activity of Pt/Al@RFC-0.6 was extremely high and its initial TOF value was up to 70000h-1 which was superior to all the catalysts in the asymmetric hydrogenation of EOPB under the same reaction.Finally,the catalyst could be reused for 15 times under acidic reaction conditions without significant degradation of performance.(3)The preparation period of aluminum-carbon composite Al@Ph FC synthesized by using phloroglucino-formaldehyde resin as carbon source was shortened on the basis of Al@RFC.Through a series of characterization,it was found that the forms both of the aluminum element and the carbon element in the two composites were same.Nevertheless,the asymmetric hydrogenation of EOPB using Pt/Al@Ph FC as catalyst could obtained 99.5% conversion and 77.4% optical selectivity.Although the catalyst’s reaction activity was reduced to some extent,it did exhibit excellent reusability that it could be reused for 20 times without significant decline.