Heterogeneous hydrogenation of nitroaromatic compounds on gold catalysts: Influence of titanium substitution in MCM-41 mesoporous supports

JOEL B. ALDERETEA; CECILIA C. TORRES; GINA PECCHI; PATRICIO REYES; CRISTIAN H. CAMPOS ; BÁRBARA PAWELEC; GRISELDA A. EIMER; ELIANA G. VASCHETTO

APPLIED CATALYSIS A-GENERAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 517 p. 110 - 119

0926-860X

A series of Ti-modified MCM-41 supports and their respective Au catalysts were prepared and characterizedto study the effect of titanium into the support and on the characteristics of the Au surface speciesfor heterogeneous hydrogenation of aromatic nitrocompounds. The systems were characterized by Xraydiffraction, Infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), diffuse reflectanceUV?vis (DRUV?vis), N2 adsorption?desorption isotherms, ICP-MS and X-ray photoelectron spectroscopy(XPS). Additionally, these catalysts were tested for the hydrogenation of nitrobenzene in a batch-typereactor using ethanol as the solvent at 25 ◦C. Based on a combined FT-IR and DRUV?vis was possibleto conclude that the Ti(IV) is incorporated into the framework of MCM-41 and Ti-containing MCM-41catalysts were more active than an MCM-41 unmodified catalyst. The Ti(X)-MCM-41 supports preparedwith Ti 2.0 wt% incorporation showed the best catalytic performance, which was attributed to an optimalnumber of isolated Ti sites that increased the Au stability on the support surface. For this system, the effectof the H2 pressure, solvent nature and recyclability of the catalyst was also studied. Finally, a quantitativestructure property relationship (QSPR) model was obtained for the catalytic activities of para-substitutednitrobenzenes. The multilinear model considered two parametric descriptors: the sigma constant () andthe hydrophobic -constant, which account for the electronic and hydrophobic effect of the substituents.