INTEC   05402
INSTITUTO DE DESARROLLO TECNOLOGICO PARA LA INDUSTRIA QUIMICA
Unidad Ejecutora - UE
artículos
Título:
"Liquid-Phase Hydrogenation of Methyl Oleate on a Ni/alfa-Al2O3 Catalyst: A Study based on Kinetic Models Describing Extreme and Intermediate Adsorption Regimes"
Autor/es:
MARIA I. CABRERA, RICARDO J.A. GRAU
Revista:
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
Editorial:
Elsevier
Referencias:
Año: 2006 vol. 260 p. 269 - 279
ISSN:
1381-1169
Resumen:
The kinetics of the hydrogenation of methyl oleate on a Ni/a-Al2O3 catalyst was studied in the absence of mass-transport limitation, at 398 < T < 443 K and 3.7 < PH2 < 6.5 bar. The kinetic modeling was performed on the basis of elementary step mechanisms involving different regimes of competition between hydrogen and methyl oleate. Admitting a distinction between occupied-sites and covered-sites by the large molecule of methyl oleate, a rigorous proposal was made to link the seemingly separate kinetic models corresponding to the extreme modes of competitive and non-competitive adsorption, without having to draw the common distinction between two types of surface sites. General rate equations were formulated without expressing opinion a priori on whether the adsorption regime is competitive or non-competitive. Then, typical LHHW rate equations for both extreme adsorption regimes were straightforwardly derived as special cases. Statistical results demonstrated the inadequacy of the models approaching non-competitive adsorption to describe the experimental data but results did not allow a definite discrimination between rival models with competitive and semi-competitive adsorption. A mechanistic model featuring dissociative adsorption of hydrogen, molecule of methyl oleate interacting with a single atom of Ni, and second insertion of hydrogen as RDS, proved to be the best candidate to describe the experimental data satisfactorily with physically reasonable parameters As a distinctive feature, the model considering semi-competitive adsorption gave additional indication that the adsorbed molecule of methyl oleate could cover up to seven surface sites. From this finding, the semi-competitive model seems to be more realistic than the competitive one.