Tandem Catalysis by Palladium Nanoclusters Encapsulated in Metal–Organic Frameworks

• Published in: ACS catalysis Vol. 4; no. 10; pp. 3490 - 3497
• Main Authors: Li, Xinle, Guo, Zhiyong, Xiao, Chaoxian, Goh, Tian Wei, Tesfagaber, Daniel, Huang, Wenyu
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 03.10.2014
• Subjects: acetalization; bifunctional catalysts; heterogeneous catalysis; nanoclusters; NANOSCIENCE AND NANOTECHNOLOGY; tandem catalysis; UiO-66; Zr-MOF; acetal; selective oxidation; bifunctional catalysts; acetalization; UiO-66; solid acid; tandem synthesis
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/cs5006635

A bifunctional Zr-MOF catalyst containing palladium nanoclusters (NCs) has been developed. The formation of Pd NCs was confirmed by transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS). Combining the oxidation activity of Pd NCs and the acetalization activity of the Lewis acid sites in UiO-66-NH2, this catalyst (Pd@UiO-66-NH2) exhibits excellent catalytic activity and selectivity in a one-pot tandem oxidation-acetalization reaction. This catalyst shows 99.9% selectivity to benzaldehyde ethylene acetal in the tandem reaction of benzyl alcohol and ethylene glycol at 99.9% conversion of benzyl alcohol. We also examined various substituted benzyl alcohols and found that alcohols with electron-donating groups showed better conversion and selectivity compared to those with electron-withdrawing groups. We further proved that there was no leaching of active catalytic species during the reaction and the catalyst can be recycled at least five times without significant deactivation.