Au-Rh and Au-Pd Nanoalloys supported on well-defined Rutile Titania Nanorods for Aromatics Hydrogenation Applications Zere Konuspayeva 1,2 , Gilles Berhault 1 , Pavel Afanasiev 1 , Thanh-Son Nguyen 1 , Ali Auyezov 2 , Mukhambetkali Burkitbayev 2 , Laurent Piccolo 1 1 Institut de Recherches sur la Catalyse et l’Environnement (IRCELYON), CNRS – Université Lyon 1, 69626 Villeurbanne Cedex, France 2 Al-Farabi Kazakh National University, Department of chemistry and chemical technology, al- Farabi avenue 71, 050038 Almaty, Kazakhstan ABSTRACT TiO 2 -supported bimetallic Au-Rh and Au-Pd nanocrystals were synthesized using both impregnation and colloidal approaches employing HAuCl 4 and RhCl 3 as precursors. The as- obtained bimetallic catalysts were then supported onto TiO 2 rutile nanorods in order to provide catalytic systems with well-defined metal-support interactions for HRTEM characterization. The results revealed the superiority of the colloidal approach over the impregnation technique to obtain bimetallic nanoparticles (4 nm in size) with tunable composition. However, for Au- Rh/TiO 2 , optimization of the procedure of the sol immobilization onto the TiO 2 support was required to avoid possible Rh re-dissolution. Preparation of Au-Pd/TiO 2 followed the same procedure but with more acidic conditions necessary to perform immobilization on the support. UV-vis spectroscopy and XRD results suggest formation of a Rh-rich shell over an Au core center for Au-Rh NPs, while Au-Pd NPs present a pure alloy structure. Au-Rh/TiO 2 was used for performing the high-pressure hydroconversion of tetralin in the presence or not of H 2 S. The results indicate a strong thioresistance induced by the addition of Au to Rh. INTRODUCTION Tuning the composition of bimetallic catalysts as well as controlling their interaction with oxide supports are critical in order to control catalytic properties for various classes of reactions. In this respect, extensive work has been performed in recent years to prepare Au-based bimetallic catalysts due to the possible enhancement of catalytic performances when combining Au with noble metals in nanoalloys [1]. However, up to now, while Au-Pd systems have been widely studied, mainly for oxidation reactions [2], Au-Rh nanoalloys have been rarely envisaged [3,4]. Moreover, the nature of the interaction between these bimetallic systems and oxide supports is not well understood due to the poorly defined morphology of most of the oxides used. Therefore, using well-defined oxide supports offers opportunities to simplify observation of the bimetallic particles – support interaction. The objective of the present study was to prepare Au-M (M = Rh, Pd) bimetallic systems by comparing the efficiency of colloidal and impregnation techniques in order to obtain nanoalloys with controlled composition. The bimetallic particles were supported on TiO 2 nanorods, which are both relevant to catalysis and convenient for in-depth HRTEM characterization. The effectiveness of adding Au to Rh-based catalytic systems is evaluated in