Effects of Ru particle size over TiO2 on the catalytic performance of CO2 hydrogenation

The influence of metal particle size over heterogeneous catalysts on the catalytic performance has always been an interesting subject due to its significance from both fundamental and practical perspectives. In this work, we regulated the synthesis of TiO 2 by the hydrolysis of different titanium precursors, and as-prepared TiO 2 supports were employed to load Ru with impregnation method. Interestingly, we synthesized three Ru-TiO 2 catalysts with different Ru particle sizes of 1.1, 2.9 and 5.2 nm. The Ru-TiO 2 catalysts were next tested for CO 2 hydrogenation reaction, the results show that the medium Ru particles on TiO 2 exhibited the best CO 2 methanation activity. Based on the characterizations, we observed that the medium Ru particles exhibited the best redox properties compared with small and large Ru particles, which was beneficial to the H 2 dissociation; in addition, the medium Ru particles exhibited a moderate ability to activate CO 2 , resulting in the most favorable formation and decomposition of bidentate bicarbonate. Consequently, the Ru-TiO 2 catalyst with medium Ru particles showed the highest activity for CO 2 methanation. This study provides a new method to prepare Ru-TiO 2 catalysts with different Ru sizes and also presents an understanding of Ru particle size effects on CO 2 hydrogenation.