Continuous-Flow Irradiation Facilitates Catalyst-Free Methane-to-Methanol Conversion.

Abstract

Converting methane to methanol (MTM) holds far-reaching practical implications, yet achieving both high productivity and high selectivity remains a longstanding challenge owing to the inertness of methane and the susceptibility of methanol to overoxidation. Here, we propose a continuous-flow irradiation system (CIS) by coupling radiation technology and flow chemistry for efficient MTM under ambient conditions. High-energy radiation promises direct methane activation in an oxidant-independent and catalyst-free manner with high efficiency, which enables its integration with continuous-flow synthesis that decouples CH4 activation from methanol formation in time and space, thereby preventing overoxidation and undesirable cascade side reactions. The CIS-MTM achieves a superior methanol production rate (68.3 μmol·h-1, at a dose rate of 7.2 kGy·min-1, 83.2 RH%, CH4 flow rate 60 mL·min-1) than most existing indirect activation routes, with economic scalability comparable to industrial methods. This work introduces radiation technology as a potential direct activation method for methane conversion.

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