Pd@-Functionalized Haloysite: A new Catalyst for Hydrogenation of Poly α-olefins

Poly α-olefins (PAOs) are saturated oligomers obtained from polymerizing of linear alpha-olefins. They are widely used as oils in the industry and considered as alternative source for the production of various types of engine oils, hydraulic, compressors, airplane fuel, etc. In fact, poly α- olefins are mostly synthesized by cationic method. In this method, the presence of unsaturated hydrocarbons with different types of double bond in oligomer decreases the stability of the produced oils. To solve this problem, hydrogenation is performed on the unsaturated oils to obtain a stable white oil with higher performance. Catalytic systems play a very important role in hydrogenating of polyα-olefins and production of white oils. Most hydrogenation catalysts partially hydrogenate PAO chains [1, 2]. Hence, development of efficient heterogeneous catalysts that could fully hydrogenate polyα-olefins is of the great importance. Halloysite nanoclays (HNTs, Al2(OH)4Si2O5.2H2O), possess high surface area, tubular morphology and high mechanical strength. They belong to the class of kaolinite group hydrated layered aluminosilicates. Recently, functionalization of the HNTs surface has been considered as a potent method for modification of the features of HNTs and expanding their applications [3]. In this regard, a novel heterogeneous catalyst was designed and synthesized through a multi-step process, including, functionalization of HNT with organosilane followed by the reaction with isotonic anhydride and immobilization of Pd(0) nanoparticles (Scheme 1). Then, the activity of the catalyst was examined for hydrogenation of polyα-olefins.