Liquid-Phase Oligomerization of 1-Hexene Using Al-MTS Catalysts

The liquid-phase oligomerization of 1-hexene (at 200 °C and 50 bar) was studied using, as catalysts, templated sol-gel aluminosilicates Al-MTS prepared in an acid medium with different Si/Al atomic ratios (7.5-110). The acid sites of the Al-MTS catalysts were analyzed using ammonia temperature programmed desorption (TPD), 27Al magic angle spinning nuclear magnetic resonance (MAS NMR), and 31P MAS NMR of the adsorbed triethylphosphine oxide (TEPO). High oligomerization conversions were always achieved (70%-80%) with an enhancement of the selectivity toward heavier hydrocarbons with decreasing Si/Al, along with a low cracking selectivity (C3-C5 < 6%). The study of the influence of the main operation variables on the performance over a standard Al-MTS sample (Si/Al = 30) indicates that an increase of the temperature (120-200 °C) led to higher selectivities toward heavier hydrocarbons, whereas the opposite trend was appreciated with the weight hourly space velocity (WHSV) (0.40-1.26 h^-1).