Highly productive framework bounded Ni²⁺ on hierarchical zeolite for ethylene oligomerization

The production of higher linear olefins via ethylene oligomerization is an applied industrial process using homogeneous catalysts in the liquid phase. Heterogeneous catalysts based on Ni supported on zeolites are attractive materials for gas phase oligomerization but typically offer a low selectivity or low conversion. Here, we investigate a tailored method to introduce the Ni²⁺ species within the hierarchical zeolite crystallization step (in situ) and compare it with the standard impregnation procedure (ex situ). The in situ engineered catalyst has a very high concentration of Ni²⁺ species, seamlessly inserted and well dispersed into the zeolite framework, with increased accessibility through meso- and micropores. This catalyst has a unique 1-butene cumulative productivity (32.7 g of 1-butene per g of catalyst) and stability for at least 48 h. This framework bounded Ni²⁺ promotes oligomerization over isomerization, cracking, and hydride transfer, while the hierarchical zeolite structure enables the discharge of coke precursors. These results pave the way for a more efficient and effective ethylene oligomerization process.