Influence of Ni-Cu alloying on Sepiolite-supported nickel catalysts in the liquid-phase selective hydrogenation of fatty acid ethyl esters

The role of Cu in Sepiolite-supported bimetallic Ni-Cu catalysts has been evaluated through the results obtained in a kinetic study on the influence of temperature in the consecutive hydrogenation of ethyl linolate to ethyl oleate and ethyl stearate, respectively. Liquid-phase hydrogenation reactions (individual and consecutive) were carried out under hydrogen pressure of 0.41 MPa in a temperature range between 305 and 337 K. Thus, the relative reactivities of linoleic and oleic ethyl esters, R(L,O), as well as the corresponding relative adsorption constants, K-L,K-O, were obtained at all temperatures studied. According to the results, in both of the Sepiolite supported catalysts studied, selectivity values steadily increased with temperature in the interval studied. Besides, R(L,O) and K-L,K-O exhibited an Arrhenius type law with temperature that enabled us to obtain several kinetic parameters affecting the selectivity of the consecutive hydrogenation process and closely related to the electronic density of supported nickel which is modified by Ni-Cu alloying.