Sunflower oil hydrogenation on Pd/C in SC propane in a continuous recycle reactor

Abstract

AbstractFluid‐phase, continuous hydrogenations of sunflower oil on 2% Pd/C were carried out in an internal recycle, radial‐flow, packed‐bed microreactor (50 cm3) using propane as supercritical‐fluid solvent. Temperature (428–488 K), oil liquid hourly space velocity (LHSV = 30–70), H2 mol composition (2–10%), and stirrer speed (52–262 rad/s) were changed according to a four‐variable, two‐level, central composite design to predict the effect of process variables on the iodine value (IV) and on trans fatty acid content (trans C18:1). Feed and product were well above the condensation conditions so that a single fluid phase was present (according to recent calculations by Pereda et al.). The total system pressure, the molar oil concentration and the catalyst mass were held constant at 20 MPa, 1 mol %, and 0.1085 g, respectively. An empirical quadratic‐form response‐surface model is shown to fit the results, and shows the regions where a potential CSTR process could be operated to obtain a certain outlet iodine value and a minimum trans C18:1 content. For the time‐on stream values used here catalyst deactivation effects were not observed. In an extension of the results, a kinetic analysis of the steady‐state CSTR reaction rate data allows determination of the kinetic constants, and their temperature dependency, for the multiple reactions of hydrogenation–isomerization network involving triglyceride species. The kinetic formalism, proposed earlier for vegetable oil hydrogenations, was used. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1545–1555, 2004