Additive-Free Ethylene Dimerization Over Well-Defined Nickel-Zeolite Catalysts

Area of Science:

• Heterogeneous catalysis
• Zeolite chemistry
• Organometallic chemistry

Background:

• Ethylene dimerization is vital but relies on inefficient organometallic catalysts with excess additives.
• Existing heterogeneous nickel catalysts for ethylene dimerization exhibit limited activity and selectivity for 1-butene.

Purpose of the Study:

• To develop a highly active and selective heterogeneous catalyst for ethylene dimerization.
• To investigate a novel Ni-Mg-Y zeolite catalyst prepared via ion-exchange.

Main Methods:

• Two-step ion-exchange synthesis of Ni-Mg-Y zeolite.
• Ethylene dimerization reaction testing.
• Advanced characterization techniques (e.g., spectroscopy, microscopy).
• Theoretical simulations (e.g., DFT calculations).

Main Results:

• Ni-Mg-Y zeolite demonstrated unprecedented performance: 3.8 × 10^5 h^-1 1-butene formation rate and 91.2% 1-butene selectivity.
• The catalyst operated effectively without any cocatalysts.
• In-situ generated Ni-alkyl motif identified as the intrinsic active site.

Conclusions:

• The developed Ni-Mg-Y zeolite is a highly promising catalyst for ethylene dimerization.
• Ethylene dimerization proceeds via the Cossee-Arlman pathway, driven by dynamic hydrogen transfer.
• This work advances heterogeneous catalysis for olefin transformations.