Study On Hydroformylation Of Propylene In Supercritical Carbon Dioxide And Critical Properties Of Supercritical Systems

Supercritical fluid(SCF) has the advantage of high diffusitivity, good solubility and transimissibility, and it is widely used in supercritical extraction and material synthesis, SCF has been used in catalysis reaction only in recent years. This work has explored hydroformylation of propylene in SCF elementarily, remarkable result has been got, the catalysis ability and selectivity in SCF is better than that in normal condition. Because the water-soluble Rhodium phosphine complex is used, the lose of Rh has been controlled, and the recycle problem of the Rh catalyst has been solved. It is proved that the research of catalysis reaction in SCF has both the research significance in academic and actual value in application. The performance of SCF as a solvent can be greatly affected by addition of a cosolvent to the system. A cosolvent can be added to a SCF to enhance its solvent strength and/or selectivity. Critical point data for these dilute SCF-cosolvent binary and ternary systems are imperative for the design of efficient supercritical separation and reaction processes. So that, it is very important to study the critical point data in binary and ternary systems.The constant volume visual method is used to measure the critical properties of CO2+toluene, CO2+cyclohexane, CO2+n-butyraldehyde, CO2+i-butyraldehyde, CO2+ methanol and CO2+alcohol binary systems. With the increase of mol% of the cosolvent, critical temperature and pressure of binary system increased, and the experimental data show a linear dependence of critical temperature and pressure with mol% of the binary system over the concentrationranges studied, and the critical temperature and pressure of cosolvent has some infection to that of binary system.In this study, the critical point data of ternary systems which is composed of supercritical carbon dioxide, trisodium salt of tri-(m-sulfonphenyl)phosphine(TPPTS) and cosolvent were measured the first time. With the increase of mol% of the cosolvent, critical temperature of ternary system increased, and the experimental data show a linear dependence of critical temperature with mol% of the ternary system over the concentration ranges studied too. But with the increase of mol% of the cosolvent, the critical pressure of ternary system close to a constant value. The comparison of the critical point of binary systems and that of ternary systems have been discussed, all the data shows that the critical temperature and pressure of ternary system is lower than that of binary system, and the reason has also been explored.With the addition of cosolvent, hydroformylation of propylene in SCF is realized, the reaction condition is explored. The reaction in SCF is compared with normal condition. With the comparison of product n/i ratio , translation rate and TON, under the condition of [Rh]=2.6. 10'5,P/Rh=25, the best reaction temperature has been got, which is T=45~50癈. It is found that under this condition, the translation rate of propylene can reach 17.2%, n/i ratio is 31~47.9. When the reaction is over, catalyst can separates from product easily, the Rh catalyst dissolves in water, the lose and recycle problem of the Rh catalyst has been solved. Under supercritical condition, the catalyst has high activity and selectivity, and the reaction temperature decreased. It proves that reaction in SCF is one of the best ways to realize homogeneous reaction and has many advantages, it has good development prospect both in the area of research and application.