Kinetics of hydrogenation of palm stearin fatty acid over Ru/Al₂O₃ catalyst in presence of small quantity of water

Abstract

The liquid phase hydrogenation of palm stearin fatty acid was studied in the presence of 2% (w/w) water, using n-dodecane as solvent. The catalyst, 5% Ru/Al₂O₃ was found to be more effective than that of Ni catalyst. The presence of water enhanced hydrogenation rate for ruthenium-supported catalyst. The kinetics for palm stearin fatty acid hydrogenation over 5% Ru/Al₂O₃ catalyst was investigated in a slurry reactor in the range of temperature (393-423 K) and H₂ pressure (0.68-2.72 MPa). The rate of hydrogenation was described in terms of reduction in iodine value (IV) using power law model. The Langmuir–Hinshelwood type kinetic expressions for a single site mechanism with molecular adsorption of H₂ was proposed, and this model provided the best fit of the experimental data. The catalyst could be reused thrice without any loss in activity.