Catalytically Active Membranelike Devices: Ionic Liquid Hybrid Organosilicas Decorated with Palladium Nanoparticles

Ionic liquid (IL) hybrid organosilicas based on 1-n-butyl-3-(3-trimethoxysilylpropyl)imidazolium cations associated with hydrophilic and hydrophobic anions decorated with well-dispersed and similar-sized (1.8–2.1 nm) Pd nanoparticles (Pd-NPs) are among the most active and selective catalysts for the partial hydrogenation of conjugated dienes to monoenes. The location of the sputter-imprinted Pd-NPs on different supports, as determined by RBS and HS-LEIS analysis, is modulated by the strength of the contact ion pair formed between the imidazolium cation and the anion, rather than the IL hybrid organosilica pore size and surface area. In contrast, the pore diameter and surface area of the hybrid supports display a direct correlation with the anion hydrophobicity. XPS analysis showed that the Pd(0) surface component decreases with increasing ionic bond strength between the imidazolium cation and the anions (contact ion pair). The finding is corroborated by changes in the coordination number associated with t...