Surface molecular imprinting over supported metal catalysts for size-dependent selective hydrogenation reactions

Abstract

Molecular imprinting of polymer matrices enables the creation of template-shaped cavities with high affinity for molecules of given shape and size. Here we introduce a surface molecular imprinting strategy to control the hydrogenation selectivity of various aromatic molecules over a supported palladium catalyst. This strategy involves the sequential adsorption over the metal surface of an aromatic template molecule followed by poisoners, resulting in the formation of non-poisoned active islands of predetermined shape and size. Because of steric constraints, these active islands exhibit high selectivity in the chemical conversion of aromatic molecules that correspond in size and shape to the templates. The elaborated strategy enables a practical application relevant to selective hydrogenation and removal of carcinogenic benzene from mixtures of aromatics. Molecular imprinting can facilitate size- and shape-selective reactions beyond traditional approaches based on porous materials, but is still not fully established for heterogeneous catalysts. Here a molecular imprinting approach is introduced to generate a supported palladium catalyst for the selective hydrogenation of benzene from mixtures of aromatic molecules.