The Binding Strength of Reactive H*: A Neglected Key Factor in Rh-Catalyzed Environmental Hydrodefluorination Reaction,ACS ES&T Engineering

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The Binding Strength of Reactive H*: A Neglected Key Factor in Rh-Catalyzed Environmental Hydrodefluorination Reaction
ACS ES&T Engineering ( IF 7.4 ) Pub Date : 2021-04-30 , DOI: 10.1021/acsestengg.1c00108
Aijiao Yuan ₁ , Huachao Zhao _{1,

2} , Wanyu Shan ₁ , Jie-Fang Sun ₃ , Jiguang Deng ₄ , Hairong Liu ₅ , Rui Liu _{1,

2} , Jing-Fu Liu _{1,

2}

Affiliation

The catalyzed reduction process plays an important role in the safe handling of environmental contaminants. It is generally believed that the adsorption of pollutants and cleavage of chemical bonds with high stability is the key and rate-determining step. Herein, using the H₂–D₂ exchange experiment, we observed a rapid decrease in the yield of HD on the Rh nanocatalyst, a state-of-the-art choice for the reduction of fluorinated organics, which indicates that the overadsorption of H/D atoms poisoned the Rh surface. The high binding energy of H/D on Rh decreases its reactivity as a reductant and is unfavorable for the adsorption/activation of the C–F bond. This dilemma is easily overcome by depositing Rh atoms onto Pd nanowires or commercial Pd/Al₂O₃. In addition to reducing the size of the Rh ensemble and therefore decreasing the H binding energy, Pd also directly spills over reactive H to the nearby Rh center; Pd@Rh shows 50 times higher mass activity and can remove persistent pollutants such as hexafluorobenzene and perfluorooctane acid under environmentally relevant conditions. Interestingly, the Pd@Rh catalyst hydrogenates halogenated phenols into value-added cyclohexanone with high selectivity. This work provides new insight into the design of advantageous nanocatalysts for environmental improvement and the recovery of resources from wastewater.

中文翻译：

反应性 H* 的结合强度：Rh 催化的环境加氢脱氟反应中被忽视的关键因素

催化还原过程在安全处理环境污染物方面起着重要作用。一般认为，污染物的吸附和高稳定性化学键的断裂是关键和决定速率的步骤。在此，使用 H ₂ -D ₂交换实验，我们观察到 Rh 纳米催化剂上 HD 的产率迅速下降，这是一种减少氟化有机物的最新选择，这表明 H 的过度吸附/D 原子毒害了 Rh 表面。H/D 在 Rh 上的高结合能降低了其作为还原剂的反应活性，不利于 C-F 键的吸附/活化。通过将 Rh 原子沉积到 Pd 纳米线或商用 Pd/Al ₂ O上，可以轻松克服这一困境₃ . 除了减小 Rh 系综的尺寸并因此降低 H 结合能之外，Pd 还直接溢出反应性 H 到附近的 Rh 中心；Pd@Rh 的质量活性提高了 50 倍，并且可以在环境相关条件下去除六氟苯和全氟辛酸等持久性污染物。有趣的是，Pd@Rh 催化剂可以高选择性地将卤代酚氢化成高附加值的环己酮。这项工作为设计用于改善环境和从废水中回收资源的有利纳米催化剂提供了新的见解。

更新日期：2021-06-11

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