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Nitrobenzene Hydrogenation on Au/TiO2 and Au/SiO2 Catalyst: Synthesis, Characterization and Catalytic Activity Cecilia Torres • Cristian Campos • Jose´ Luis Garcı´a Fierro • Marcelo Oportus Patricio Reyes

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Received: 24 February 2013 / Accepted: 31 May 2013 / Published online: 13 June 2013 Ó Springer Science+Business Media New York 2013

Abstract Recently, gold has been proposed as an active phase for the hydrogenation of nitro-arenes. This metal has been rarely used in hydrogenation reactions because gold does not possess hydrogen chemisorption capacity. However, small gold particles behave differently and they may be able to chemisorb hydrogen to same extent, leading to possible activity in hydrogenation reactions. This may provide an advantage because the reactions catalyzed by highly dispersed gold particles may be better controlled. In this work, TiO2 and SiO2 supported Au catalysts were prepared by the deposition–precipitation method using urea and NaOH to precipitate the metallic component at different temperatures and hydrogen pressures. The metal loading for all the catalysts was 1 wt%. The catalysts were characterized by X-ray diffraction, high resolution transmission electron microscopy among others. The catalysts were then evaluated in the hydrogenation of nitrobenzene in a batch type reactor at 25 °C. All the catalysts were active in the hydrogenation reaction and the major obtained product was aniline. Keywords Gold
Nitrobenzene
Hydrogenation
Heterogeneous

C. Torres (&)
C. Campos
M. Oportus
P. Reyes (&) Grupo de Cata´lisis por Metales, Facultad de Ciencias Quı´micas, Universidad de Concepcio´n, Edmundo Larenas 129, Concepcio´n, Chile e-mail: [email protected] P. Reyes e-mail: [email protected] J. L. G. Fierro Grupo de Energı´a y Quı´mica Sostenible (EQS), Instituto de Cata´lisis y Petroleoquı´mica (ICP-CSIC), c/Marie Curie s/n Cantoblanco, Madrid, Spain

1 Introduction The preparation of compounds with potential biological activity has received considerable attention at both laboratory and industrial levels. For the production of fine chemicals to be economically viable, high selectivity and specificity is an important requirement. In addition, environmentally benign processes are fundamental in drug production. A process of particular interest that embodies these stringent requirements is the catalytic production of aromatic amines from aromatic nitro compounds [1, 2]. This process has been approached by three different procedures: (i) by stoichiometric reduction of the corresponding aromatic nitro compounds using iron, tin, zinc or a metal sulfide such as Na2S. However, this method displays low selectivity for nitro group, and large amounts of waste acids and residues are generated during the reaction. (ii) By catalytic hydrogenation of nitro compounds with H2 over supported noble metal catalysts, e.g. Pd, Pt, Ru and Ni catalysts [3–7], etc. Nevertheless, the high hydrogenation ability of this metals usually procedures the hydrogenation of other groups existing in the arene substrates lead