Nonoxidative coupling of methane to olefins and aromatics over molten W-In bimetal catalyst

Direct nonoxidative conversion of methane to ethylene, aromatics and hydrogen has been recognized as an attractive utilization of natural gas, but qualified catalyst faces huge challenges. Most catalysts reported for this reaction are deactivated fast by carbon deposition. Herein, we demonstrated an active, selective and stable molten tungsten-indium bimetal catalyst entrapped in a silica gel, offering 11% methane conversion in single pass, with C₂/C₃-C₅/aromatics hydrocarbon distributions of 36%/4%/54% at 950 °C. A little carbon was formed during reaction, but spontaneously floated onto tungsten-indium liquid surface and moved onto silica surface thereby leaving the tungsten-indium liquid surface clean. No deactivation was thus observed even after 120-hour testing. Theoretical calculations and experimental results reveal that methane is converted into ethane on indium clusters, followed by gas-phase thermal cracking to ethylene and tandem aromatization on tungsten clusters to aromatics. The high stability and controllable hydrocarbon distribution promise our catalyst great potential of practical applications.