Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering , Nanjing Tech University , Nanjing 211816 , China.
Institute of Advanced Study, College of Chemistry , Nanchang University , Nanchang 330031 , China.
ACS Appl Mater Interfaces. 2020 Jan 15;12(2):2516-2524. doi: 10.1021/acsami.9b19160. Epub 2020 Jan 2.
The heterogeneous hydrogenation of α,β-unsaturated compounds requires understanding of the structure-activity relationship of metallic catalysts in consideration of solvent-mediated processes. In this work, a CoAl hydrotalcites (CoAl-HTs)-supported Pt nanoparticle catalyst is employed to study the effect of solvent water and HTs interlayer water on the aqueous-phase selective hydrogenation of cinnamaldehyde (CALD). Pt/CoAl-HTs catalyst displays 5075 h of specific reaction rate and 89% of C═O hydrogenation selectivity at 80 °C under 20 bar of H. Combined results of isotope-labeling experiments and theoretical DFT calculations demonstrate that the water-mediated hydrogen-exchange pathway exists in the reaction with a relatively lower-energy barrier in comparison to the direct H-dissociated hydrogenation pathway. The results also reveal that the interlayer water species of HTs support participate in the hydrogen-exchange reaction. Based on the H-D exchange results, these HTs interlayer water species can promote H activation and dissociation processes and thus accelerate the CALD hydrogenation reaction even under solvent-free conditions.
α,β-不饱和化合物的多相氢化需要考虑溶剂介导过程，理解金属催化剂的结构-活性关系。在这项工作中，采用 CoAl 水滑石（CoAl-HTs）负载的 Pt 纳米粒子催化剂来研究溶剂水和 HTs 层间水对肉桂醛（CALD）在水相中选择性氢化的影响。Pt/CoAl-HTs 催化剂在 20 巴 H 2 下于 80°C 下显示出 5075 h 的比反应速率和 89%的 C═O 氢化选择性。同位素标记实验和理论 DFT 计算的综合结果表明，与直接 H 脱附和氢化途径相比，水介导的氢交换途径在反应中存在相对较低的能量障碍。结果还表明，HTs 的层间水物种支持参与氢交换反应。基于 H-D 交换结果，这些 HTs 层间水物种可以促进 H 的活化和离解过程，从而即使在无溶剂条件下也能加速 CALD 氢化反应。
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