Tandem Nonoxidative Coupling of Methane and Carbon Dioxide Reduction via Pulsed Joule Thermochemistry

The conversion of CH4 into higher hydrocarbons and CO2 reduction are promising yet hindered by poor selectivity and the cost of green H2. Methane can act as an intrinsic H2 donor for CO2 reduction, but its activation typically leads to dry reforming to syngas at high temperatures. Here, we demonstrate that rapid pulsed Joule heating (RPH) of CH4/CO2 mixtures enables the direct nonoxidative coupling of methane to C2 hydrocarbons (acetylene and ethylene) while simultaneously reducing CO2 via the reverse water-gas shift reaction. Compared to continuous Joule heating, RPH achieves higher CH4 conversion at lower average temperatures, requires 60% less power, and enhances carbon element stability by suppressing the reverse Boudouard reaction. Kinetic modeling reveals that RPH’s microsecond pulses favor C–C coupling over reforming and aromatization due to time scale separation. This strategy can also convert biogas directly into intermediates for C3+ oxygenates, bypassing the energy-intensive dry reforming process.