Highly dispersed Pd clusters/nanoparticles encapsulated in MOFs via in situ auto-reduction method for aqueous phenol hydrogenation

Huang, X. and Li, X. and Xia, W. and Hu, B. and Muhler, M. and Peng, B.

Volume: 109 Pages: 167-175
DOI: 10.1016/j.jmst.2021.08.079
Published: 2022

In this work, a novel in situ auto-reduction strategy was developed to encapsulate uniformly dispersed Pd clusters/nanoparticles in MIL-125-NH2. It is demonstrated that the amino groups in MIL-125-NH2 can react with formaldehyde to form novel reducing groups (-NH[sbnd]CH2OH), which can in situ auto-reduce the encapsulated Pd2+ ions to metallic Pd clusters/nanoparticles. As no additional reductants are required, the strategy limits the aggregation and migration of Pd clusters and the formation of large Pd nanoparticles via controlling the amount of Pd2+ precursor. When applied as catalysts in the hydrogenation of phenol in the aqueous phase, the obtained Pd(1.5)/MIL-125-NH-CH2OH catalyst with highly dispersed Pd clusters/nanoparticles with the size of around 2 nm exhibited 100% of phenol conversion and 100% of cyclohexanone selectivity at 70 °C after 5 h, as well as remarkable reusability for at least five cycles due to the large MOF surface area, the highly dispersed Pd clusters/nanoparticles and their excellent stability within the MIL-125-NH-CH2OH framework. © 2021

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