Pd immobilization on the multi-amine functionalized halloysite as an efficient catalyst for hydrogenation reaction: An experimental and computational study

In this study, the best thrichloro-and amine-compounds (i.e. 2,4,6-trichloro-1,3,5-triazine and metformin, respectively) were selected among seven possible candidates by molecular modelling tool for the synthesis of a multi-dentate nitrogen-containing ligand. Besides ligand composition, the type of solvent for Pd immobilization was studied as well. Taking advantage of simulation results, the catalyst was fabricated via amine functionalization of halloysite followed by sequential reactions with 2,4,6-trichloro-1,3,5-triazine and metformin and Pd immobilization. Then, the prepared catalyst was characterized. The results showed that small Pd nanoparticles with a mean diameter of 1.9 +/- 0.4 nm were homogeneously dispersed on the functionalized halloysite. The performance of the catalyst was evaluated for the hydrogenation of nitroarenes in aqueous media. The results demonstrated high catalytic activity of the catalyst. Furthermore, the catalyst was reusable for several times with the low loss of performance and Pd leaching. It was also found out that the catalyst was selective towards nitro group reduction and could promote the reaction of steric substrates, too.