Homogeneous and Heterogeneous Nickel-Catalyzed Olefin Oligomerization: Experimental Investigation for a Common Mechanistic Proposition and Catalyst Optimization
Abstract
Only a few catalytic transformations can be efficiently catalyzed
by both homogeneous or heterogeneous technologies,
with short olefin oligomerization promoted by a nickel-based
catalysts among them. Homogeneous and heterogeneous catalysis
are often opposed in terms of activity, active-site description
or recyclability, traditionally mentioned as “homogeneous
versus. heterogeneous”. Unlike previous studies, we propose
to emphasize the similarities between both catalysis by comparing
industrially representative results obtained in continuous
flow-mode under similar mild conditions. A detailed analysis
of both primary products of olefins oligomerization, and
a set of secondary products obtained in experimental assays
completed with recently published results of DFT calculations
prompted us to postulate a common mechanistic pathway for
nickel-catalyzed ethylene oligomerization. Heterogeneous metallic
ethylene oligomerization, for which nickel active sites
identification has indeed long been under debate, seems to
follow the Cossee–Arlman mechanism, well accepted as major
mechanism in the homogeneous counterpart. This analysis allowed
us to design an unprecedented heterogeneous catalyst
active for ethylene and butene oligomerization.