Selectivity and Microkinetic Insights on Ethylene Oligomerization over Ni Encapsulated in a Brønsted-less Hollow ZSM-5 Zeolite

by Abed, Mohamed, khairova, Hita, Velisoju, Morlanes, Meijerink, Emwas, Vernuccio, Castaño
ChemCatChem Year: 2025 DOI: https://doi.org/10.1002/cctc.202500957

Abstract

We encapsulated Ni nanoparticles in a hollow ZSM-5 zeolite catalyst using the dissolution-recrystallization method to catalyze ethylene oligomerization. Our aim is to engineer an idealized catalyst free of Brønsted acid contributions to kinetics or deactivation, having isolated and encapsulated Ni2⁺–zeolite species, to study the intrinsic oligomerization kinetics on Ni2⁺–zeolite through an experimental and microkinetic standpoint. We proved how the hollow architecture encapsulates both Ni2⁺ and NiO species, being the former significantly more active and selective toward dimerization. A comprehensive microkinetic model, grounded in the Cossee-Arlman mechanism and parameterized using experimental data, provides a detailed understanding of the reaction network on isolated Ni2⁺ sites. The model reveals that while linear butene formation dominates, its selectivity decreases with increasing ethylene conversion, temperature, and pressure, highlighting the contribution of isomerization pathways at elevated temperatures. This study focuses on the method to develop isolated oligomerization sites and then studies the intrinsic microkinetic pathways and rates.

Keywords

OLG MKM HCE