Supported Single-Atom Manganese Catalysts for the Trimerization of Ethylene
Selective ethylene oligomerization via oxidative cyclization, forming metalacyclic intermediates, is typically catalyzed by molecular titanium and chromium complexes to produce butenes, hexenes, or octenes, depending on the supporting ligand framework. However, this mechanism requires significant electron density at the metal active site and is not known to be generalizable to other first-row transition metals. Here, we computationally investigate the electronic modulation of five transition metals (Mn, Fe, Co, Ni, and Cu) supported on titania (TiO₂) through reductive lithium intercalation to promote selective oligomerization via oxidative cyclization, using density functional theory (DFT). Our findings predict that Mn/LiTiO₂ exhibits high catalytic activity due to the exergonic nature of oxidative cyclization with two ethylene molecules. Additionally, lithium titanate (LiTiO₂) supports enhance catalytic performance compared to TiO₂. Experimental validation confirms that Mn/LiTiO₂ achieves higher conversion rates and improved selectivity towards hexene (C₄:C₆ = 1:2.6). The enhanced activity is attributed to lithiation, which alters the electronic environment around Mn active sites. Mechanistic studies reveal that the formation of a seven-membered ring, a key intermediate for hexene formation, is more favorable on LiTiO₂ than TiO₂. This work provides the first evidence of Mn catalyzing selective ethylene oligomerization via oxidative cyclization in either homogeneous or heterogeneous catalysis.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- US Department of Energy; USDOE Office of Science - Office of Basic Energy Sciences
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 3374277
- Journal Information:
- Chemcatchem, Journal Name: Chemcatchem; ISSN 1867-3880
- Country of Publication:
- United States
- Language:
- English
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