Nickel Complexes Immobilized in Modified Ionic Liquids Anchored in Structured Materials for Ethylene Oligomerization

This work describes the study of ethylene oligomerization reactions catalyzed by nickel-beta-diimine complexes immobilized on beta-zeolite, [Si]-MCM-41 (Mobil Composition of Matter 41) and [Si,Al]-MCM-41 modified with an ionic liquid. XRD and N-2 adsorption and desorption analyses were used to characterize the modified supports-namely, IL-Zeo beta, IL-MCM-41 and IL-Al-MCM-41-and the data showed that material organization remained intact even after incorporation of ionic liquid. N-2 adsorption and desorption analyses suggested that ionic liquid can be confined in pores of support materials. Catalytic properties of synthesized materials were tested under different conditions. The following parameters were varied: Al/Ni molar ratio, temperature, pressure and catalyst loading. The homogeneous catalysts were more active but less selective in ethylene oligomerization, relative to heterogeneous ones, which can be attributed to the effect of confinement suffered by catalyst within channels of the support materials. NiIL-Zeo beta complexes were active, with activities greater than 23 s(-1) and selectivities higher than 80% for butenes, including more than 85% of 1-butene. On the other hand, the NiIL-MCM-41 system was less active than NiIL-Zeo beta complexes, with activities above 1 s(-1) with 100% selectivity for butenes (96% in 1-butene). NiIL-Al-MCM-41 system was more active than NiIL-MCM-41 system and showed an activity of 2.3 s(-1) with 90% selectivity in 1-butenes.