Adsorption Deposition of Palladium Hexafluoroacetylacetonate on Porous Matrices in Supercritical CO₂

The adsorption deposition of palladium hexafluoroacetylacetonate Pd(hfa)₂ on porous supports (γ-Al₂O₃ and hypercrosslinked polystyrene, HCP) in supercritical CO₂ is considered. The conditions for a transition of the Pd(hfa)₂/CO₂ system to a monophase region have been studied. Due to its reasonably high solubility in CO₂, the palladium compound can be deposited at relatively low pressures (~8.5 MPa) in the system. The adsorption of Pd(hfa)₂ on the given supports is well described by the Langmuir equation. An increase in the pressure in the system under isothermal conditions negatively affects the amount of adsorbed precursor because of the adsorption of CO₂ and distribution offset in the system. The limiting adsorption increases at elevated temperatures in the system under isochoric conditions.