Dual-task composite of halloysite and ionic liquid for the synthesis and hydrogenation of polyalphaolefins

Polyalphaolefins (PAOs) are synthetic oils with wide industrial applications. Synthesis of PAOs is fulfilled through oligomerization of alpha-olefin monomers and hydrogenation of the resultant oil. Oligomerization catalyst is AlCl3 that is toxic and corrosive. To reduce the content of AlCl3 ionic liquid/AlCl3 systems are recently suggested. Hydrogenation is also a catalytic process catalyzed by precious metals. To reduce the required amount of this costly catalyst, precious metals need to be immobilized on a suitable support that can provide uniform dispersion. In this study, a dual-task composite of halloysite clay and ionic liquid is reported that can be used for both oligomerization and hydrogenation processes. In fact, this composite played the role of supported ionic liquid to be applied along with AlCl3 in the 1-octene oligomerization. On the other hand, it was utilized as a support for the immobilization of Pd nanoparticles to give hydrogenation catalyst. The results indicated that the PAO obtained from this catalytic system exhibited extremely uniform microstructure with high long chain branching (74.5%) and VI (147) values. Moreover, examining the catalytic activity of palladated halloysite-ionic liquid composite confirmed that it could assure formation of fine Pd particles with homogeneous metal dispersion. Notably, the catalyst showed high activity under optimized conditions (temperature = 130 degrees C, hydrogen pressure = 7 bar and catalyst loading = 5 wt%) and rendered the hydrogenated PAO in 98% yield with bromine index of 49 Br/100. Furthermore, the catalyst exhibited high recyclability and slight Pd leaching. [GRAPHICS] .

Automated summary

A composite material composed of halloysite clay and ionic liquid is reported in this study, which can be used for both oligomerization and hydrogenation processes. The PAO obtained from this catalytic system exhibits a uniform microstructure and high performance. The palladated composite shows good catalytic activity and recyclability.