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

Area of Science:

• Heterogeneous Catalysis
• Materials Science
• Chemical Engineering

Background:

• Nonoxidative coupling of methane (NOCM) is challenging due to the need for C-H bond activation, C-C bond formation, and hydrogen management without oxidants.
• Conventional catalysts often rely on expensive noble metals and operate at high temperatures.

Purpose of the Study:

• To develop a low-temperature catalyst for efficient nonoxidative methane coupling.
• To elucidate the catalytic mechanism of methane conversion over atomically dispersed metal nanopowders.

Main Methods:

• Utilized a catalytic microreactor coupled with synchrotron-based photoionization mass spectrometry for in situ product and intermediate detection.
• Performed electronic structure calculations on model Ti-Al-B clusters to understand the catalytic mechanism.

Main Results:

• Achieved low-temperature C-H activation and nonoxidative C-C coupling of methane at 800 K, significantly below the gas-phase decomposition threshold.
• Observed predominant ethylene formation with selectivity up to 78% among C-C coupled products.
• Identified methyl radicals, C2 hydrocarbons, and molecular hydrogen as reaction products.

Conclusions:

• Atomically dispersed Ti-Al-B nanopowder exhibits cooperative catalytic activity for methane conversion.
• Titanium facilitates C-H activation, boron acts as a hydrogen reservoir, and aluminum stabilizes intermediates.
• This earth-abundant catalyst offers a sustainable alternative for light alkane conversion, providing design principles for future catalysts.