Effect of gas pressure on the phase behaviour of organometallic compounds

The knowledge of the phase behaviour of organometallic compounds in supercritical CO2 is the key factor for determining the feasibility of homogeneous catalysis in supercritical fluid reaction. In the present study, the solid–liquid–gas equilibrium line for the system CO2/Cu(thd)2, CO2/Pt(COD)Me2 and He/Pt(COD)Me2 was determined from 0.1 MPa to 25 MPa. In addition, experimental solubility data of Cu(thd)2 in CO2 at 333 K and pressures ranging from 10 MPa to 17 MPa as well as of Pt(COD)Me2 in CO2 at 313 K, 333 K and 353 K and pressures ranging from 12 MPa to 32 MPa are presented. The solubility data are correlated using the linear relationship between the logarithm of the solubility and the logarithm of the reduced density of pure CO2 proposed by Kumar and Johnston as well as an extension of the theory of dilute solution proposed by Mendez-Santiago and Teja. Both approaches gave reasonable results in the correlation of the experimental solubility data.