Intraparticle diffusion limitations in the hydrogenation of monounsaturated edible oils and their fatty acid methyl esters

Intraparticle diffusion limitation in the hydrogenation and isomerization of fatty acid methyl esters (FAMEs) and edible oils (triacylglycerol, TAG) in porous nickel catalyst was investigated both under reactive and under inert conditions. Under reactive conditions, the diffusion coefficients were determined from the best fits of the model simulations applying the intrinsic reacting kinetics of monounsaturated FAME hydrogenation to experiments under diffusion limited conditions. For 0.02 < PH2 < 0.50 MPa, an effective hydrogen diffusion coefficient of De,H2 = (1.6 ± 0.7) × 10-10 m2/s (T = 443 K) was obtained in Pricat 9910 (sample 1992). TAG hydrogenations, at 373 < T < 443 K and 0.30 < PH2 < 0.50 MPa, appear to be limited by diffusion limitation of TAG, yielding De,TAG = (4.5 ± 2.2) × 10-13 (T = 373 K), (2.0 ± 0.9) × 10-12 (T = 403 K), and De,TAG = (3.3 ± 1.1) × 10-12 m2/s (T = 443 K). The temperature dependency of De follows the relation Deη/T = 2 × 10-7 (m2 Pa)/K (η is the fluid viscosity, Pa s) for 37...