A novel cerium-based metal-organic framework supported Pd catalyst for semi-hydrogenation of phenylacetylene

Phenylacetylene is a detrimental impurity in the polymerisation of styrene, capable of poisoning catalysts even at ppm levels and significantly degrading the quality of polystyrene. The semi-hydrogenation of phenylacetylene to styrene instead of ethylbenzene is, therefore, an important industrial process. We report a novel cerium(IV)-based metal-organic framework (denoted as Ce-bptc), which is comprised of {Ce6} clusters bridged by biphenyl-3,3’,5,5’-tetracarboxylate linkers. Ce-bptc serves as an ideal support for palladium nanoparticles and the Pd@Ce-bptc catalyst demonstrates an excellent catalytic performance for semi-hydrogenation of phenylacetylene, achieving a selectivity of 93% to styrene on full conversion under ambient conditions with excellent reusability. In situ synchrotron X-ray powder diffraction and electron paramagnetic resonance spectroscopy revealed the binding domain of phenylacetylene within Ce-bptc and details of the reaction mechanism.