(768b) Kinetics of the Ethylene Oligomerization Under Supercritical Fluid Conditions

In this work, we report the effect of supercritical conditions on the kinetics of ethylene oligomerization over metal exchanged aluminum silicate catalysts. Previous works from our research group [1], [2] focused on the use of supercritical conditions on the ethylene oligomerization over heterogeneous catalysts. Our previous results indicate higher catalyst stability under supercritical ethylene as compared with subcritical conditions. More recently, we provided visual evidence of the coke solubilization by supercritical ethylene.[2] Still, to this date, the kinetics and mechanisms of the ethylene oligomerization under supercritical conditions has not been studied, and it is required to advance the development of this novel process. In a recent work, we were able to develop the reaction mechanism and kinetics of the ethylene oligomerization under subcritical fluid conditions. We calculated the activation energies for the consumption of ethylene and the production of C₄, C₆, and C₈ products. We also performed an adsorption study to elucidate the mechanism involved in the ethylene adsorption over the Ni-H-Beta catalyst prior to the chain growth step. We developed the kinetics of the reaction under subcritical fluid conditions using the Langmuir-Hinshelwood kinetics. In this talk, we proposed to develop the kinetics under supercritical ethylene conditions over the Ni-H-Beta catalyst.

In this talk, we will report the activation energies involved in the production of lighter products, such as C₄, C₆, and C₈, and also heavier hydrocarbons, such as C₁₀, C₁₂, and C₁₄. Furthermore, we will discuss a reaction network based on the product distribution and reaction order involved in the production of each one of the products under supercritical ethylene conditions. The effects of weight hourly space velocity (WHSV) on the product selectivity and conversion will help to validate the pathway proposed and identify new pathways not identified before. A parallel solubility study will be reported to elucidate the products formed by the desorption of coke from the catalyst from the products formed due to the solubility of coke in the supercritical ethylene. The results obtained will be compared with the kinetic under subcritical conditions and the differences will help to highlight the advantages of using supercritical fluid conditions on the ethylene oligomerization over the Ni-H-Beta catalyst.

[1] O. Jan, K. Song, A. Dichiara, and F. L. P. Resende, “Oligomerization of Supercritical Ethylene over Silica-Alumina Catalysts,” Chem. Eng. Sci., vol. 197, pp. 212–222, 2018.

[2] G. V. S. Seufitelli and F. L.P.Resende, “Study of the catalytic reactions of ethylene oligomerization in subcritical and supercritical media over a NiBEA catalyst,” Appl. Catal. A Gen., vol. 576, pp. 96–107, 2019.