Brønsted acid-promoted ethylene dimerization to 1-butene over Ni-containing zeolite catalysts

Abstract

Ethylene dimerization is a critical industrial process traditionally catalyzed by homogeneous systems employing cocatalysts or solvents. Although heterogeneous catalysts show potential to circumvent these limitations, they often exhibit low activity and limited selectivity toward 1-butene. In this work, a transition-metal-confined FAU zeolite catalyst featuring precisely defined, coordinatively unsaturated Ni sites and abundant acidic functionalities, is explored for the reaction. This unique catalyst, denoted as H–Ni@Y, demonstrates remarkable ethylene dimerization performance without the need for cocatalysts or additive activators. In a fixed-bed reactor, an exceptional 1-butene formation rate of 4.28 × 10⁵ h⁻¹ and high 1-butene selectivity of 83.6% can be achieved with H–Ni@Y catalyst. Comprehensive characterization results and DFT calculations elucidate the significant influence of Brønsted acidity on the catalytic performance, revealing the in situ-generated Ni–alkyl species as the active sites. The reaction proceeds via the Cossee–Arlman mechanism, facilitated by dynamic proton transfer processes. These findings provide valuable insights into the rational design of heterogeneous catalysts for industrially relevant ethylene dimerization.