Densities and phase equilibria of supercritical hydrogen, propane and vegetable oil mixtures. Experimental data and thermodynamic modeling

N. COTABARREN; E.A. BRIGNOLE; P. HEGEL; S. PEREDA

Antibes Juan Les Pins

Simposio; 12nd International Symposium on Supercritical Fluids ISSF2018; 2018

International Society for the Advancement of Supercritical Fluids

Supercritical reactors have potential applications in heterogeneously catalyzed hydrogenation of nonvolatile substrates. Main advantages: i) eliminates the problem of low solubility of hydrogen in the liquid phase, ii) enhance mass transfer at supercritical fluid-solid interface and iii) control of reactants concentration.The supercritical hydrogenation processes can be carried out in continuous or batch reactors in any case the knowledge of the mixture volumetric properties is needed to understand the reaction kinetics and to estimate the residence time in the design of continuous reactors.The hydrogenation of vegetable oils, using propane as a supercritical co-solvent increased the reaction rate orders of magnitude in comparison with the conventional approach.Rovetto et al measured the phase equilibria of typical hydrogenation mixtures, with supercritical propane, triglycerides, fatty esters and alcohols. These highly size asymmetric mixtures were modeled with the GCA-EOS by Pereda et al, This model was applied for the phase equilibrium engineering design of supercritical reactors. However the GCA-EOS fails to correlate and predict volumetric properties with the desired accuracy.Cismondi and Mollerup showed the limitation of classic cubic equations of state to predict PVT properties and proposed a three parameters equation namely the Redlich-Kwong-Peng-Robinson (RK-PR) EOS which was applied successfully to highly asymmetric mixtures.