Yan-Ting Li, Wen-Gang Cui, Ying-Fei Huo, Lei Zhou, Xinqiang Wang, Fan Gao, Qiang Zhang, Wei Li and Tong-Liang Hu
{"title":"Acetylene semi-hydrogenation catalyzed by Pd single atoms sandwiched in zeolitic imidazolate frameworks via hydrogen activation and spillover†","authors":"Yan-Ting Li, Wen-Gang Cui, Ying-Fei Huo, Lei Zhou, Xinqiang Wang, Fan Gao, Qiang Zhang, Wei Li and Tong-Liang Hu","doi":"10.1039/D4MH01787K","DOIUrl":null,"url":null,"abstract":"<p >The semi-hydrogenation of alkynes into alkenes rather than alkanes is of great importance in the chemical industry, and palladium-based metallic catalysts are currently employed. Unfortunately, a fairly high cost and uncontrollable over-hydrogenation impeded the application of Pd-based catalysts on a large scale. Herein, a sandwich structure single atom Pd catalyst, Z@Pd@Z, was prepared <em>via</em> impregnation exchange and epitaxial growth methods (Z stands for ZIF-8), in which Pd single atoms were stabilized by pyrrolic N in a zeolitic imidazolate framework (ZIF-8). Semi-hydrogenation of acetylene was performed and Z@Pd@Z achieved 100% acetylene conversion at 120 °C with an ethylene selectivity of more than 98.3% at an extra low Pd concentration. Z@Pd@Z exhibited a specific activity of 1872.69 mL<small><sub>C<small><sub>2</sub></small>H<small><sub>4</sub></small></sub></small> mg<small><sub>Pd</sub></small><small><sup>−1</sup></small> h<small><sup>−1</sup></small>, surpassing most of the reported Pd-based catalysts. The existence of Pd single atoms coordinated by nitrogen (Pd–N<small><sub>4</sub></small>) was verified by XAS (synchrotron X-ray absorption spectroscopy), which provided active sites for H<small><sub>2</sub></small> dissociation and the dissociated hydrogen quickly spilled over the surface of the outer ZIF layer to hydrogenate alkyne to ethene; besides, the catalytic activity could be controlled by adjusting the thickness of the outer ZIF layer. The confinement of the ZIF on Pd single-atom sites and the high energy barrier of ethylene hydrogenation were found to be responsible for the superior C<small><sub>2</sub></small>H<small><sub>2</sub></small> semi-hydrogenation activity. This work opens up valuable insights into the design of ZIF-derived single-atom catalysts for efficient acetylene selective hydrogenation.</p>","PeriodicalId":87,"journal":{"name":"Materials Horizons","volume":" 7","pages":" 2351-2359"},"PeriodicalIF":12.2000,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Materials Horizons","FirstCategoryId":"88","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2025/mh/d4mh01787k","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The semi-hydrogenation of alkynes into alkenes rather than alkanes is of great importance in the chemical industry, and palladium-based metallic catalysts are currently employed. Unfortunately, a fairly high cost and uncontrollable over-hydrogenation impeded the application of Pd-based catalysts on a large scale. Herein, a sandwich structure single atom Pd catalyst, Z@Pd@Z, was prepared via impregnation exchange and epitaxial growth methods (Z stands for ZIF-8), in which Pd single atoms were stabilized by pyrrolic N in a zeolitic imidazolate framework (ZIF-8). Semi-hydrogenation of acetylene was performed and Z@Pd@Z achieved 100% acetylene conversion at 120 °C with an ethylene selectivity of more than 98.3% at an extra low Pd concentration. Z@Pd@Z exhibited a specific activity of 1872.69 mLC2H4 mgPd−1 h−1, surpassing most of the reported Pd-based catalysts. The existence of Pd single atoms coordinated by nitrogen (Pd–N4) was verified by XAS (synchrotron X-ray absorption spectroscopy), which provided active sites for H2 dissociation and the dissociated hydrogen quickly spilled over the surface of the outer ZIF layer to hydrogenate alkyne to ethene; besides, the catalytic activity could be controlled by adjusting the thickness of the outer ZIF layer. The confinement of the ZIF on Pd single-atom sites and the high energy barrier of ethylene hydrogenation were found to be responsible for the superior C2H2 semi-hydrogenation activity. This work opens up valuable insights into the design of ZIF-derived single-atom catalysts for efficient acetylene selective hydrogenation.