Phase equilibrium calculations for the hydrogenolysis of fatty acid methyl esters at supercritical conditions

S. PEREDA; T: FORNARI; S.B. BOTTINI; E.A. BRIGNOLE

Santa Fe - Argentina

Conferencia; ENPROMER 2001; 2001

CERIDE

Fatty alcohols are one of the major oleochemicals and can be produced by the catalytic hydrogenation of fatty acid methyl esters. In the traditional gas-liquid hydrogenolysis of high molecular weight esters, the reaction rates are limited by the depletion of hydrogen at the catalyst surface, due to low hydrogen solubility and mass transport resistance in the liquid phase. Recent experimental work (van der Hark et al., 1999) shows that it is possible to carry out the reaction under a single homogeneous phase, by using supercritical propane as a co-solvent. At these conditions it is possible to control the concentration of all reactants at the catalyst surface, increasing greatly the reaction rate and selectivity of the process. Unfortunately, there is no experimental phase equilibrium data available in the literature for ternary or quaternary mixtures of hydrogen, propane, fatty acid alcohols and esters. In this work, the group contribution with association equation of state GCA-EOS (Gros et al., 1996) has been used to predict phase equilibria for ternary mixtures of hydrogen – propane – fatty alcohols and hydrogen – propane – fatty acid methyl esters, on the basis of good correlations of binary phase equilibrium data. Regions of one, two and three fluid phases were identified in the ternary mixtures with fatty alcohols. By the calculation of phase envelopes at different propane concentrations and different hydrogen/reactant molar ratios, it was possible to determine conditions for a feasible one-phase region. References: Gros H.P., S.B.Bottini and E.A.Brignole, Fluid Phase Equilibria, 116, 537-544, 1996 Van der Hark S., M.Harrod and P.Moller, JAOCS, 76, 1363-1370, 1999