Lubricant hydrogenation over a functionalized clay‐based Pd catalyst: A combined computational and experimental study

Abstract

In the world of chemical catalysis and with the importance of being especially in the petrochemical industry, hydrogenation reactions play a central role. Within this framework, the hydrogenation of polyalphaolefins (PAOs) is receiving increasing attention. In this work, for the sake of efficiency and to furnish an efficient support for the immobilization of Pd nanoparticles, a new catalyst containing the 1,3‐diaminopropane (DAP) diamine for the decoration of the halloysite (HNT) outer surface is used. The resulting catalytic system exhibited high activity in the hydrogenation of PAOs and high catalyst recyclability since it could be used for several reaction runs, with no appreciable loss of the catalytic activity and Pd leaching. In addition, the nature of the heterogeneous catalysis was demonstrated by a hot filtration test. Density functional theory (DFT) calculations not only unveil the reaction mechanism, in which the rate determining step was determined mechanistically, but also confirm the best location of the palladium nanoparticles, placed between the diamino ligands in the halloysite surface. Furthermore, the computational simulations rationalize why experimentally the catalytic process requires hydrogen pressure of 7 bar and temperature of 130°C to reach high yield.

The mono and bimetallic catalysts for hydrogenation of PAO lubricants

“…In this study, three HNT-supported catalysts, including two monometallic catalysts, Pd/HNT and Rh/HNT as well as one bimetallic catalyst, PdÀ Rh/HNT were synthesized via wet-impregnation method. [14] Typically, HNT (2 g) was suspended in toluene (30 mL) and ultrasounded for 20 min under power of 120 W. Then, a solution of the metal precursor(s), Pd(OAc) 2 (0.03 g in 10 mL toluene) or/and RhCl 3 (0.03 g in 10 mL MeOH) was prepared and added drop by drop to HNT suspension. The mixture was stirred for 2 h at ambient temperature under Ar atmosphere.…”

Halloysite functionalized with dendritic moiety containing vitamin B1 hydrochloride as a bio-based catalyst for the synthesis of 5-hydroxymthylfurfural

“…More recently, use of bio-based compounds 22 has been introduced to develop natural-based catalysts for HMF production. In this line, use of halloysite clay (Hal) 23,24 that is an aluminosilicate clay with unique tubular morphology and opposite electric charge on both surfaces as a supporting material is of great interest [25][26][27] . Interestingly, Hal has instinct acidic feature that renders it a potent candidate for developing acidic catalysts 28 .…”