2022 Annual Meeting

(683c) Nonoxidation Coupling of Methane over Nano-Layer Platinum Catalysts on Two-Dimensional Metal Carbides (MXenes)

Authors

Zhe Li, Iowa State University
Prabudhya Chowdhury, Purdue University
Zhenwei Wu, Purdue University
Tao Ma, Ames Laboratory
Johnny Zhuchen, Purdue University
Gang Wan, SLAC National Accelerator Laboratory
Tae-Hoon Kim, Department of Industrial Engineering, Lamar University
Dapeng Jing, Department of Energy Ames Laboratory
Peilei He, Iowa State University
Pratik Potdar, Purdue University
Lin Zhou, Ames Laboratory
Zhenhua Zeng, Purdue University
Xiulin Ruan, Purdue University
Jeffrey T. Miller, Purdue University
Jeffrey Greeley, Purdue University
Yue Wu, Iowa State University
Arvind Varma, Purdue University
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.