Pd catalysts supported on γ-Al2O3 immobilized with ionic liquids: an efficient and recyclable system for C‒C bond formation

Abstract

A novel γ-Al₂O₃/IL-Pd catalyst was designed and synthesized; this catalyst features highly dispersed deposition of active palladium nanoparticles on the surface of porous γ-Al₂O₃, and its catalytic performance and recyclability are improved. The incorporation of ionic liquids is critical to catalyst design since it facilitates the complete dispersion of active metals through chelation; this effectively prevents the formation of palladium black and addresses catalyst deactivation. The interaction between the ionic liquid and the support likely occurs through specific coordination reactions; this interaction significantly enhances the recovery and reusability of the catalyst by preventing the leaching and sintering of the palladium nanoparticles. This approach not only resolves the agglomeration issue inherent to γ-Al₂O₃, but also further optimizes the catalyst performance. In the Suzuki‒Miyaura coupling reaction, the new catalyst demonstrates remarkable catalytic activity and achieves a tetramethoxybiphenyl yield of up to 99% within a remarkably short reaction time of just 30 min, without the need for inert gas protection. Notably, after ten consecutive cycles, the catalyst’s performance remains at 94%, outperforming many existing catalysts and confirming its exceptional stability and recyclability. Given its high efficiency, stability, and reusability, this catalyst can likely serve as a high-performance multifunctional catalytic platform for a range of significant organic synthesis reactions.

Graphical abstract