Synergistic effect of acid-base and redox properties of nano Au/CeO2-cube on selective hydrogenation of nitrobenzene to aniline

Abstract

Catalysts with 1 wt% gold doped on various morphologies of ceria (nano-cubes, nano-rods and nano-polyhedra), were prepared by the deposition precipitation method. The samples are characterized and used to catalyze the hydrogenation of nitrobenzene in ethanol. The highest nitrobenzene conversion (92%) and aniline selectivity (90%) are achieved from the catalyst supported by nano-cube CeO2 (1 wt% Au/CeO2-cube). The calcination temperatures of both the support and catalyst can influence the acid-base properties, the morphology and the valance of Au and Ce, which are key factors in the adsorption of nitrobenzene, the desorption of aniline and the formation of active H− species, respectively. We find that small-size Au nanoparticles (2.1 nm) with appropriate ratio of Au0 to Auδ+, acid/base sites with sufficient density and appropriate strength, and oxygen vacancy of ceria on the interface of Au and ceria are favorable to the formation of aniline on 1 wt% Au/CeO2-cube.