INCAPE   05401
INSTITUTO DE INVESTIGACIONES EN CATALISIS Y PETROQUIMICA "ING. JOSE MIGUEL PARERA"
Unidad Ejecutora - UE
artículos
Título:
Liquid-phase hydrogenation of acetophenone over silica-supported Ni, Co and Cu catalysts: Influence of metal and solvent
Autor/es:
A.F. TRASARTI; N.M. BERTERO; C.R. APESTEGUÍA; A.J. MARCHI
Revista:
APPLIED CATALYSIS A-GENERAL
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2014 vol. 475 p. 282 - 291
ISSN:
0926-860X
Resumen:
In this work, we studied the influence of solvent and metal nature on
the liquid-phase hydrogenation of acetophenone (AP) over Ni/SiO2,
Co/SiO2 and Cu/SiO2. Catalysts were prepared by wetness
impregnation method with metal loads of about 7¨C8 wt%. Catalytic tests were
performed in a batch reactor, at 363 K and 10 bar (H2), using 2-propanol (IPA),
cyclohexane (CHX), toluene (TOL) and benzene (BEN) as solvents. Considering the
three catalysts, the general pattern for the initial hydrogenation rate was: Ni/SiO2
> Co/SiO2 > Cu/SiO2, whereas the trend for
selectivity to 1-phenylethanol (PHE) was just the oppo-site. AP can interact
with nickel metal surface through both ¨CC=O group and aromatic ring and thus
the aromatic alcohol and saturated compounds were obtained. Instead, cobalt and
copper metal surfaces interact preferentially with the ¨CC=O group leading to
selective hydrogenation of AP into PHE. In addition, an important interaction
between ¨CC¨COH group of PHE and Co/SiO2surface takes place, leading to rapid
alcohol hydrogenolysis into ethylbenzene. The general activity pattern with the
four solvents was: IPA > CHX ¡Ý TOL ¡Ý BEN. The magnitude of solvent influence
on the catalytic performance strongly depended on the metal nature. The most
significant solvent effect took place with Ni/SiO2, whereas the less
noticeable influence was observed in the case of Cu/SiO2. From
pseudo-homogenous kinetic modeling and temperature-programmed desorption, the
following noteworthy observations arose: (1) IPA has a positive contribution by
hydrogen transfer and/or AP activation by polarization; (2) the magnitude of
the positive IPA influence on AP hydrogenation rate follows the trend: Ni/SiO2
> Co/SiO2 > Cu/SiO2; (3) CHX has a neutral
contribution because of its weak adsorption on the metal phase and low
interaction with reactant and products; (4) the effect of TOL and BEN is
clearly negative for Ni/SiO2 due to block-age of active sites by
strong adsorption of solvent on the metallic surface; (5) the effect due to
strong adsorption of TOL and BEN is much less noticeable on Co/SiO2 and
Cu/SiO2, as a consequence, the pat-tern for AP hydrogenation rates
in BEN and TOL is Cu/SiO2 > Co/SiO2 > Ni/SiO2.
Selectivity to PHE was less influenced by solvent nature. However, in the case
of Ni/SiO2 and Co/SiO2, maximum PHE yields and
selectivities increased with the solvent¨Cmetal interactions, mainly due to
inhibition of the PHE hydrogenolysis. Cu/SiO2 was always 100%
selective to PHE in all of the solvents. These results are clearly indicating
that the magnitude of the solvent effect on catalytic performance strongly
depends on the metal nature.