Supercritical Co <sub> 2 </ Sub> Multi-system Behavior In Propylene Hydroformylation Reaction,

Supercritical fluids (SCFS) have many unique properties such as high diffusivity, low viscosity and enhanced compressibility, which make them widely applied as attractive solvents for extraction, chemical preparation and supercritical reaction. In this dissertation hydroformylation of propylene in supercritical CO2 was explored thoroughly and the critical properties of its related supercritical systems were also investigated in detail. The constant volume visual method is used to investigate the critical property of the supercritical systems, by which the dependence of pressure on temperature was determined and the related critical pressure and critical temperature were all measured simultaneously. Firstly, the relationship between pressure and temperature of near-supercritical and supercritical CO2 were firstly studied. P-T-ρfigure describing CO2 at different densities was established, and the behavior of dew point, critical point and bubble point together in different densities was investigated. The compressibility factor and the compressibility factor at phase splitting point of CO2 were both for the first time calculated. It was concluded that density of CO2 can be separated into three regions that are low density (0.2~0.35g/cm3), medium density (0.35~0.57g/cm3) and high density (0.57~0.8g/cm3) respectively by way of phase splitting phenomenon and regularities of compressibility. The difference between different density regions of high pressure homogeneous CO2 was also discussed. Secondly, critical properties of supercritical CO2 + ethanol binary system at different densities and different mole fractions of ethanol were investigated. PTρ figures of binary systems at different ethanol contents were for the first time described. It was found that pressure of supercritical CO2 + ethanol binary system increase linearly with the increasing temperature, from which P-T lines show certain convergent feature in definite concentration of ethanol and the convergent points move to the region of higher temperature and pressure with the increasing ethanol compositions. The dependence of critical points of CO2 + ethanol binary system on its density and ethanol concentration was discussed in details. It was found that critical points increase linearly with the increasing mole fraction of ethanol in definite density. The critical compressibility factors Zc of supercritical CO2 + ethanol binary systems at different compositions of ethanol were calculated and Zc-ρ figure was obtained accordingly. It was found from Zc-ρfigure that compressibility factors at phase splitting points of supercritical CO2 unitary or binary systems decline linearly with the increasing density, by which dew point, critical point or bubble point can be predicted precisely.Then critical properties of different supercritical multi systems that have n-butyraldehyde, i-butyraldehyde, ethanol and water respectively as cosolvent were firstly studied in the same condition. The result is that critical points are different when cosolvents are different and both physical property and critical feature of cosolvent have great effect on critical points of supercritical system. At the same time, critical properties of supercritical CO2+ethanol+CO +H2 quaternary system, supercritical CO2+ethanol+C3H6 ternary system and supercritical CO2+ethanol+C3H6+CO+H2 quinary system were investigated successively. For CO2+ethanol+CO+H2 quaternary system, critical pressure increases linearly and critical temperature declines linearly with the increasing mole fractions of CO and H2. For CO2+ethanol+C3H6 ternary system, critical pressure declines linearly and critical temperature increases linearly with the increasing mole fractions of C3H6. Furthermore, the effect of CO and H2 on both pressure and temperature of the supercritical reaction system is larger than that of C3H6.Last, with Rh(asas)2(CO)2 as catalyst precursor, TPPTS as Rhodium ligand and supercritical CO2 as reaction reagent, hydroformylation of propylene in SCF was realized and the reaction condition was...