Structure-dependent selective hydrogenation of cinnamaldehyde over high-surface-area CeO2-ZrO2 composites supported Pt nanoparticles

- High-surface-area CeO2-ZrO2 composites were successfully prepared.
- Strong interactions between Pt species and composites were formed.
- High catalytic selective hydrogenation performance was achieved.
- Synergism between electron-rich Pt0 and surface defects was confirmed.

Tetravalent metal oxides, such as ceria and zirconia, are widely used as support materials in a broad range of heterogeneous catalytic processes. Herein, high-surface-area CeO2-ZrO2 composite supports with micro/mesoprous structures were first fabricated successfully by a low temperature solution-phase method without the use of any additional templates and surfactants and resulting supported platinum nanoparticles were employed in liquid-phase selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, a key reaction for the production of important chemicals. It was found that the component of CeO2-ZrO2 composites strongly influenced surface structures of catalysts, and consequently determined the nature of platinum species and the catalytic properties of catalysts. When platinum was dispersed on the CeO2-ZrO2 composite with the Ce/Zr molar ratio of 1:1, a high cinnamyl alcohol yield of 89%, together with an extremely high turnover frequency value of 10423 h-1, could be achieved without the use of additional alkali. Such high catalytic performance, which was superior to those of most known supported Pt-based catalysts previously reported, was mainly attributable to the synergism between electron-rich metallic Pt species and surface defects (i.e., Ce3+ species and oxygen vacancies), thereby greatly promoting the chemisorption and activation of carbonyl group in cinnamaldehyde. Moreover, the porous network of CeO2-ZrO2 composites is beneficial to the stabilization of Pt nanoparticles, thereby preventing the leaching and the growth of Pt particles in the course of reaction. This work offers a better understanding of the role of high-surface-area porous CeO2-ZrO2 composite supports for highly efficient selective hydrogenation of α,β-unsaturated aldehydes in supported precious-metal-based catalysts.