Achieving highly selective acetylene semi-hydrogenation in an ethylene-rich gas stream is of great industrial importance. Herein, we construct isolated single Pd atom in a polyoxometalate-based metal-organic framework (POMOF). The unique internal environment allows this POMOF to separate acetylene from acetylene/ethylene gas mixtures and confine it close to the single Pd atom. After semi-hydrogenation, the resulting ethylene is preferentially discharged from the pores, achieving a selectivity of 92.6 %. First-principles simulations reveal that the adsorbed acetylene/ethylene molecules form hydrogen bond networks with oxygen atoms of SiW₁₂O₄₀⁴⁻ and create dynamic confinement regions, which preferentially release the produced ethylene. Besides, at the Pd site, the over-hydrogenation of ethylene exhibits a higher reaction energy barrier than the semi-hydrogenation of acetylene. The combined advantages of POMOF and single Pd atom provides an effective approach for the regulation of semi-hydrogenation selectivity.

中文翻译：

---

多金属氧酸盐基金属-有机骨架作为分子筛，用于在孤立的单 Pd 原子位点上进行乙炔的高选择性半氢化

在富含乙烯的气流中实现高选择性乙炔半氢化具有重要的工业意义。在此，我们在基于多金属氧酸盐的金属有机框架 (POMOF) 中构建了孤立的单个 Pd 原子。独特的内部环境使这种 POMOF 能够将乙炔从乙炔/乙烯气体混合物中分离出来，并将其限制在单个 Pd 原子附近。半加氢后，生成的乙烯优先从孔隙中排出，选择性达到92.6%。第一性原理模拟表明，吸附的乙炔/乙烯分子与 SiW ₁₂ O ₄₀ ^{4− 的}氧原子形成氢键网络并产生动态限制区域，优先释放产生的乙烯。此外，在 Pd 位点，乙烯的过加氢比乙炔的半加氢表现出更高的反应能垒。PMOF 和单个 Pd 原子的综合优势为调节半氢化选择性提供了一种有效的方法。