@article{01HTS1PR5ZY8YE2BZ32SPNX2XA,
  abstract     = {{Defected and amine-loaded zirconium-based metal–organic frameworks (MOF) UiO-66(Zr) have been characterized and chemically assessed in a condensation reaction of acetone and 4-nitrobenzaldehyde. The present work focuses primarily on the production of the aldol adduct as the main product while minimizing the formation of the enone adduct as a side product. Four analogues with varying numbers of missing linkers in the hexanuclear secondary building units, from one to four out of a total of 12, were synthesized. Thorough characterization showed that an increased number of defects results in an enhanced acidity, a higher internal surface area, and an increased accessibility of coordinatively unsaturated Zr-sites. The catalytic performance assessment revealed that defects, to a certain extent, positively affect the selectivity towards the aldol adduct, i,e. the catalyst, which is missing 3 of the 12 linkers, exhibits the highest activity in a solvent-free environment with a turnover frequency (TOF) amounting to 8.03 10-3 s−1. This TOF value is approximately double of the catalyst with 1.4 defects, which exhibited a TOF of only 4.41 10-3 s−1. Excluding more than three linkers more likely leads to 'missing cluster defects' and causes a decrease in the reaction rate towards the aldol adduct. A reduction in overall catalytic activity was observed upon functionalization with amine groups (UiO-66-NH2). Functionalization with L-proline (UiO-66Lpr) resulted in a shift from an acid to a basic reaction mechanism which was reflected by an improved selectivity towards the aldol adduct while maintaining a reasonable overall activity level. The best performances were obtained working solvent-free or with hexane as a solvent, while polar/semi-polar solvents hindered the catalyst performance. An 18-hour stability test demonstrated the robustness of defected and functionalized UiO-66.}},
  articleno    = {{115471}},
  author       = {{Aljammal, Nour and Lauwaert, Jeroen and Biesemans, Bert and Vandevyvere, Tom and Sabbe, Maarten and Heynderickx, Philippe and Thybaut, Joris}},
  issn         = {{0021-9517}},
  journal      = {{JOURNAL OF CATALYSIS}},
  keywords     = {{Defects,Acid catalyst,Aldol,Ac acetone,TEMPERATURE-PROGRAMMED DESORPTION,DESIGN PARAMETERS,REACTION PATHWAYS,BRONSTED ACIDITY,PROTON TOPOLOGY,SITES,MODULATION,CONDUCTIVITY,CHEMISTRY,ALDEHYDES}},
  language     = {{eng}},
  pages        = {{17}},
  title        = {{UiO-66 metal-organic frameworks as aldol condensation catalyst : impact of defects, solvent, functionality on the catalytic activity and selectivity}},
  url          = {{http://doi.org/10.1016/j.jcat.2024.115471}},
  volume       = {{433}},
  year         = {{2024}},
}

Altmetric

View in Altmetric

Web of Science

Times cited: