In Situ Generation of Cu0 Supported on TiO2 Aerogel as a Catalyst for the Vapour Phase Hydrogenation of Nitrobenzene to Aniline

This study is first to demonstrate a new strategy to synthesize Cu nanoparticles (NPs) supported on TiO 2 (Cu@TiO 2 ) catalyst towards the vapor phase hydrogenation of nitrobenzene. The experimental design involved the four different loadings (10, 15, 20 and 30 wt%) of Cu NPs onto the TiO 2 aerogel to produce a complex with high surface area and increased pore volume. The developed catalysts were characterized using N 2 physisorption analysis, powder-XRD studies, H 2 -temperature programmed reduction, field emission scanning electron microscopy–EDAX, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The characterisation results specified that the surface area, mesoporosity, the effective dispersion of Cu nanoparticles onto the TiO 2 support exerted a significant influence on their catalytic activities. Further, it was found that the resulted process led to the complete in situ reduction of Cu 2+ to Cu 0 , and fine dispersion of Cu 0 NPs on the surface of TiO 2 . Thus, no further pre-reduction of the catalyst was required. The optimized 20 wt% Cu@TiO 2 catalyst achieved about 94% nitrobenzene conversion with maximum aniline selectivity (> 98%), with enhanced stability where the catalyst was found to be active up to 15 h of continuous catalytic reactions. From the study, it is found that this approach is promising and provides insights into the fundamental understanding on the importance of aerogel materials as versatile catalysts. Graphical Abstract