Crystal phase effects on the structure and performance of ruthenium nanoparticles for CO2 hydrogenation†
The effect of TiO2 phase structure on the dispersion of Ru nanoparticles was investigated in this study. Rutile-type TiO2 (r-TiO2) appears to be a superior support to prohibit the aggregation of RuO2 during calcination in air. Compared with anatase-type TiO2 (a-TiO2) supported Ru nanoparticles (4.0 ± 2.4 nm), r-TiO2 supported ones exhibited a narrower particle size distribution (1.1 ± 0.2 nm). This unique property was attributed to a strong interaction between RuO2 and r-TiO2 in terms of the formation of the Ru–O–Ti bond, which was confirmed by X-ray absorption measurements and H2-TPR experiments. This strong interaction not only promotes to a great extent the highly efficient dispersion of Ru nanoparticles, but also prevents their aggregation. As a result, the Ru/r-TiO2 catalysts displayed a much higher activity and thermal stability than the Ru/a-TiO2 in the reaction of CO2 methanation.