The Rhodium Catalyst Catalyzes The Asymmetric Hydrogenation Of Terpenes

Turpentine is a kind of valuable renewable natural resource and chemical raw material.Its main components are a-pinene and P-pinene which are the isomeric compounds and have active chemical properties.Therefore,a-pinene and ?-pinene are very active for many reactions,such as hydrogenation,oxidation,polymerization and so on.Pinane can be prepared by catalytic hydrogenation of pinene.Pinane is an important intermediate for the synthesis of linalool,citronellol as well as vitamin E,which is widely used in perfume and medicine production.Pinane includes two kinds of cis and trans isomers.Because the activity of cis-pinane is much higher than that of trans-pinane,the cis-pinane is primarily demand for industrial manufacture.Pine resources are abundant in our country,and turpentine oil has a high yield,but its utilization rate of the deep processing is low.Therefore,the study of turpentine asymmetric hydrogenation catalyst has a broad prospect in preparation of cis-pinane with high additional value,and it is bound to play an important role in accelerating the development of deep processing of oleoresin.At present,the catalyst for catalytic hydrogenation of turpentine mainly include nickel catalysts and precious metal catalysts.Compared with noble metal catalysts,nickel-based catalysts posses a series of shortcomings with high temperature,high pressure,severe service conditions and poor safety,as well as poor selectivity.so the development of new catalysts has important significance for achieving hydrogenation of pinene at low temperature and pressure.In this work,the complex[Rh(COD)Cl]2 was prepared and supported on activated carbons for hydrogenation of pinene.The whole research was divided into four parts which were as follows:(1)The effects of preparation conditions on the catalytic properties had been investigated.The suitable conditions were obtained:molar ratio of COD and RhCl3·3H2O was 3.5:1,reflux temperature was 80?,reflux time was 3h.The hydrogenation conditions of a-pinene were investigated by single factor and orthogonsl experiments,the optimum reaction conditions were obtained:reaction temperature 45?,reaction pressure 2.5MPa,2.5%of the catalyst to raw material quality,reaction time 4h.Under these conditions,reproducibility experiments were conducted,the results showed that the catalyst had better activity,and the repeatability was better,the conversion of ?-pinene was above 98%,the selectivity of cis-pinane was over 97%.(2)A series of exploration experiments were investigated.The results showed the hydrogenation activity of ?-pinene was higher than that of a-pinene catalyzed by supported rhodium catalys,so the raw materials of latter experiments were ?-pinene.The effects of major factors such as support type,oxidant concentration and loading of rhodium on the performance of catalysts had been investigated.The optimum conditions of the preparation of catalysts were as follows:with C acted as carrier,oxidan concentration copt%,rhodium content wopt%.(3)Carrier C supported[Rh(COD)Cl]2 catalysts were prepared and employed in hydrogenation of ?-pinene.The hydrogenation conditions of ?-pinene were studied by single factor and orthogonal experiments.The optimum conditions were obtained:reaction temperature Topt ?,reaction pressure Popt MPa,xopt%of the catalyst to raw material quality,reaction time topt h.Under these conditions,reproducibility experiments were conducted,the results showed that the catalyst had better activity,and the repeatability was better,the conversion of ?-pinene was above 99%,the selectivity of cis-pinane was over 89%.The investigation experiments of catalyst life showed that the catalyst were continuously used for 4 times.(4)Carrier,homogeneous[Rh(COD)Cl]2 catalyst and supported rhodium catalyst were characterized by IR,XPS and BET.BET results showed that the specific surface area of carrier C was 1076.85m2/g,the specific surface area of oxidation carrier C was 923.81m2/g,carrier C was rich in microporous structure.IR and XPS result showed that[Rh(COD)Cl]2 catalyst was successfully immobilized on carrier C,the cause of deactivation of the catalyst was that the Rh active component of[Rh(COD)Cl]2 catalyst was easy to lose in the running process.