Catalytic hydrogenation of 2,3,5-trimethylbenzoquinone over Pd nanoparticles confined in the cages of MIL-101(Cr)

A series of Pd@MIL-101(Cr) catalysts with different Pd loadings were prepared by incorporating Pd nanoparticles into the highly porous and hydrothermally stable metal-organic framework MIL-101(Cr) via an incipient-wetness impregnation method and then characterized by XRD, N-2 adsorption, CO chemisorption, XPS, and TEM techniques as well as by the elemental analysis. These prepared catalysts were applied in the catalytic hydrogenation of 2,3,5-trimethylbenzoquinone (TMBQ) to 2,3,5-trimethylhydroquinone (TMHQ) in a high-pressure batch reactor. The results reveal that the intrinsic activity of the MIL-101(Cr)-based catalysts is closely related to the Pd loading in MIL-101(Cr) and 2.0 wt.% Pd/MIL-101(Cr), in which Pd nanoparticles mainly within a range of 2-3 nm in diameter are confined in the mesoporous cages of MIL-101(Cr), shows the highest catalytic activity and selectivity with excellent reusability among the catalysts investigated, much superior to activated carbon supported Pd catalysts. (C) 2013 Elsevier B.V. All rights reserved.