The active-site structure, reaction mechanism, and product selectivity of the industrially important selective hydrogenation of 1,3-butadiene are investigated using first principles for an emerging single-atom Pd catalyst anchored on graphene. Density functional theory calculations suggest that the mono-π-adsorbed reactant undergoes sequential hydrogenation by Pd-activated H₂. Importantly, the high selectivity towards 1-butene is attributed to the post-transition-state dynamics in the second hydrogenation step, which leads exclusively to the desorption of the product. This dynamical event prevails despite the existence of energetically preferred 1-butene adsorption on Pd, which would eventually lead to complete hydrogenation to butane and be thus inconsistent with experimental observations. This insight underscores the importance of dynamics in heterogeneous catalysis, which has so far been underappreciated.

中文翻译：

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锚定在石墨烯上的单个 Pd 原子催化 1,3-丁二烯的选择性氢化：动力学的重要性†

使用第一原理研究了锚定在石墨烯上的新兴单原子 Pd 催化剂的工业上重要的选择性氢化 1,3-丁二烯的活性位点结构、反应机理和产物选择性。密度泛函理论计算表明单π吸附的反应物通过Pd活化的H _{2进行连续氢化}. 重要的是，对 1-丁烯的高选择性归因于第二加氢步骤中的后过渡态动力学，这完全导致产物的解吸。尽管在 Pd 上存在能量优选的 1-丁烯吸附，但这种动力学事件仍然存在，这最终会导致完全氢化成丁烷，因此与实验观察结果不一致。这一见解强调了动力学在多相催化中的重要性，而这一点迄今为止被低估了。