(683c) Nonoxidation Coupling of Methane over Nano-Layer Platinum Catalysts on Two-Dimensional Metal Carbides (MXenes)
AIChE Annual Meeting
2022
2022 Annual Meeting
Catalysis and Reaction Engineering Division
Hydrocarbon Conversion I: Nonoxidative processes for hydrocarbon conversion
Friday, November 18, 2022 - 8:36am to 8:54am
Efficient and direct conversion of methane to value-added products has been a long-term challenge in shale gas applications. Activation of the first C-H bond is essential to methane conversion but is often followed by over-dehydrogenation, leading to coke formation. Here, we show that atomically thin nanolayers of Pt with a single or double atomic layer thickness, supported on a two-dimensional molybdenum-titanium carbide (MXene), catalyze nonoxidative coupling of methane to ethane/ethylene (C2). The first-layer Pt atoms favorably occupy the hollow sites (HCP sites) above the topmost C atoms of the MXene support, which are stabilized by Pt-Mo bonds at the metal-support interfaces. Kinetic and theoretical studies reveal that the Pt nanolayers activate the first C-H bond of methane to form methyl radicals that favor desorption over further dehydrogenation and thus suppress coke deposition. At 750 °C and 7% methane conversion, the catalyst runs 72 hours of continuous operation without deactivation and exhibits >98% selectivity towards C2 products, with a turnover frequency (TOF) of 0.2-0.6 s-1. Our findings provide a fundamental understanding of the metal-support interactions between Pt and the surfaces of transition metal carbides and create a new path for developing atomically thin supported metal catalysts.