Low-Temperature Non-Oxidative Coupling of Methane on Atomically Dispersed Titanium–Aluminum–Boron Nanopowder

Nonoxidative coupling of methane represents a long-standing challenge in heterogeneous catalysis, as it requires activation of the carbon-hydrogen (C-H) bond, controlled carbon-carbon (C-C) bond formation, and effective hydrogen management without relying on oxidants. Here, we report a low-temperature C-H activation and nonoxidative C-C coupling of methane over atomically dispersed titanium-aluminum-boron nanopowder (Ti-Al-B NP) utilizing a catalytic microreactor coupled to synchrotron single-photon photoionization reflectron time-of-flight mass spectrometry. The soft-ionization, in situ probing method detects the <i>nascent</i> reaction products and radical intermediates under operando conditions, including methyl radical, C2 hydrocarbons, and molecular hydrogen. Methane activation is initiated at 800 K, approximately 700 K below the gas-phase decomposition threshold, leading predominantly to ethylene formation with selectivity reaching up to 78% among the C-C coupled products. Electronic structure calculations on model Ti-Al-B clusters elucidate a cooperative catalytic mechanism in which titanium enables methane adsorption and C-H activation, boron acts as a reversible hydrogen reservoir, and aluminum stabilizes methylene intermediates, thereby facilitating selective C-C coupling and dehydrogenation. These findings establish a distinct catalyst architecture for nonoxidative methane coupling based on earth abundant elements alternative to expensive platinum and other noble metal-containing conventional catalysts and provide molecular-level design principles for controlling dehydrogenation and subsequent C-C bond formation in challenging light alkane conversions.