Experimental data and thermodynamic modeling of physicochemical properties for the design of supercritical hydrogenation reactors

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

Villa Carlos Paz, Córdoba

Conferencia; XI Iberoamerican Conference on Phase Equilibria and Fluid Properties for Process Design; 2018

Universidad Nacional de Córdoba - Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada (CONICET-UNC)

Heterogeneous catalytic gas-liquid reactions are intensified when carried out in the homogenous fluid phase by means of a supercritical co-solvent. For instance, supercritical propane is used to enhance yield in the hydrogenation of vegetable oils, which shows a reaction rate three orders of magnitude higher compared to that carried out in conventional gas-liquid systems. 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.Rovetto et al[1] 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[2]. The model was a roboust tool for performing phase equilibrium engineering studies and designing supercritical reactor [3]. However the GCA-EOS fails to correlate and predict volumetric properties with the desired accuracy. In this work, we report experimental PvT data of the reactive mixture H2+sunflower oil + propane. In addition, the phase equilibria and PvT data are modeled with the GCA and RK-PR equations of state, respectively. The isochoric method not only provides PvT information under the reaction conditions, but also the reactive system compressibility. Based on correlations of pure component PvT behavior, RK-PR predicts accurately the density of binary and ternary mixtures, in spite of the data sensitivity to the mixture composition and global density. This results can be applied to other similar supercritical hydrogenation systems. The isochoric method not only provides PvT information under the reaction conditions, but also the reactive system compressibility, key variable to attain enhanced transport properties.