Direct, Nonoxidative Conversion of Methane to Ethylene, Aromatics, and Hydrogen

TLDR

The efficient use of natural gas requires catalysts that activate methane’s first C‑H bond while suppressing complete dehydrogenation and overoxidation. The reaction starts with catalytic generation of methyl radicals, proceeds through gas‑phase steps, and isolated iron sites prevent C‑C coupling, oligomerization, and coke deposition. Single iron sites in silica enable atom‑economical, nonoxidative methane conversion to ethylene and aromatics, achieving 48.1 % conversion and 48.4 % ethylene selectivity at 1363 K with >99 % hydrocarbon selectivity, and remain stable over 60 h without deactivation.

Abstract

The efficient use of natural gas will require catalysts that can activate the first C-H bond of methane while suppressing complete dehydrogenation and avoiding overoxidation. We report that single iron sites embedded in a silica matrix enable direct, nonoxidative conversion of methane, exclusively to ethylene and aromatics. The reaction is initiated by catalytic generation of methyl radicals, followed by a series of gas-phase reactions. The absence of adjacent iron sites prevents catalytic C-C coupling, further oligomerization, and hence, coke deposition. At 1363 kelvin, methane conversion reached a maximum at 48.1% and ethylene selectivity peaked at 48.4%, whereas the total hydrocarbon selectivity exceeded 99%, representing an atom-economical transformation process of methane. The lattice-confined single iron sites delivered stable performance, with no deactivation observed during a 60-hour test.