Pd Immobilized on Functionalized Halloysite: an Efficient Catalyst for Hydrogenation Reaction

Halloysite (HNT) is dioctahedral 1:1 layered aluminosilicate with the chemical and physical features similar to that of kaolinite. The tubular morphology of HNT as well as its biocompatibility and availability render it a potential candidate for various applications such as drug delivery, composites, catalysis etc. [1]. It is easy to imagine that in the near future HNTs can replace some synthetic tubular nanomaterials such as carbon nanotubes. In the case of catalytic purposes, HNT is mostly surface functionalized prior to use. This can improve the interactions of HNT with the immobilized catalytic species [2].Hydrogenation is a well-established process both in the chemical and petroleum refining industries. Hydrogenation is conventionally carried out in the presence precious metals such as Pd. To reduce the required amount of the catalyst and improve recyclability, precious metals have been mostly immobilized on a porous support, such as a natural clay or a synthetic oxide.In this study, a novel catalyst based on HNT has been synthesized. To prepare the catalyst a four-step procedure has been applied. More precisely, HNT was first functionalized with APTS and then reacted with epichlorohydrine. The resulting compound was further functionalized with diamines and palladated. Then, the catalytic activity of the prepared catalyst for the hydrogenation of polyalphaolefin oils has been studied. Initially, the reaction variables (hydrogen pressure, catalyst loading, reaction temperature) have been optimized. In the following, the generality of the developed protocol as well as the recyclability of the catalyst were studied.

Keywords:

hydrogenation , halloysite , catalyst , Pd