Efficient hydro-finishing of polyalfaolefin based lubricants under mild reaction condition using Pd on ligands decorated halloysite.

To achieve efficient hydrofinishing of polyalfaolefin based lubricants under mild reaction condition, a novel catalyst is designed and fabricated through supporting Pd nanoparticles on ligand functionalized halloysite clay. In this line, first, using DFT calculations a scan of a library of 36 diamines was performed to find the most proper ligand that can provide the best interactions with Pd nanoparticles, improve Pd anchoring and supress Pd leaching. Characterization of the rather strong covalent and ionic interactions by a Mayer Bond Order analysis, and the non-covalent interactions by NCI plots as well, unveiled the preference for a particular system. The perfect in silico candidate was then studied on an experimental level, and also by studying its reaction profile for the hydrogenation of ethylene by calculations. In the experimental section, halloysite was functionalized with the selected ligand in simulation part and employed for the hydrofinishing of polyalfaolefin type lubricants. Characterization results revealed successful synthesis of the nano catalyst containing tiny Pd nanoparticles with a mean diameter in the range of 2.37 ± 0.5 nm, which homogeneously dispersed on the functionalized halloysite. The synthesized catalyst exhibited excellent activity (98% hydrogenation yield after 6 h) under mild reaction condition (T = 130 °C and P = 6 bar). Furthermore, the catalyst can be recycled for several times with insignificant Pd leaching and loss of its activity.