Conventional thermochemical syntheses by continuous heating under near-equilibrium conditions face critical challenges in improving the synthesis rate, selectivity, catalyst stability and energy efficiency, owing to the lack of temporal control over the reaction temperature and time, and thus the reaction pathways1,2,3. As an alternative, we present a non-equilibrium, continuous synthesis technique that uses pulsed heating and quenching (for example, 0.02 s on, 1.08 s off) using a programmable electric current to rapidly switch the reaction between high (for example, up to 2,400 K) and low temperatures. The rapid quenching ensures high selectivity and good catalyst stability, as well as lowers the average temperature to reduce the energy cost. Using CH4 pyrolysis as a model reaction, our programmable heating and quenching technique leads to high selectivity to value-added C2 products (>75% versus <35% by the conventional non-catalytic method and versus <60% by most conventional methods using optimized catalysts). Our technique can be extended to a range of thermochemical reactions, such as NH3 synthesis, for which we achieve a stable and high synthesis rate of about 6,000 μmol gFe−1 h−1 at ambient pressure for >100 h using a non-optimized catalyst. This study establishes a new model towards highly efficient non-equilibrium thermochemical synthesis.
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We acknowledge the support from the University of Maryland A. James Clark School of Engineering. We acknowledge the Maryland NanoCenter, the Surface Analysis Center and the AIM Lab. We thank M. R. Zachariah and D. J. Kline from the University of California, Riverside for their help on the temperature measurements. We thank E. Schulman from the University of Maryland, College Park for her help on the energy cost calculations. D.L. acknowledges the support from the Department of Energy, Office of Fossil Energy (DE-FE0031877). D.G.V. acknowledges the support from the Department of Energy, Office of Energy Efficiency and Renewable Energy and Advanced Manufacturing Office (DE-EE0007888-9.5). The Delaware Energy Institute acknowledges the support and partnership of the State of Delaware in furthering the essential scientific research being conducted through the RAPID projects. Y.J. acknowledges the support from the National Science Foundation (NSF EFRI DCheM-2029425).
L.H., Y.Y., Q.D. and D.L. report a patent application of ‘High-temperature shock heating for thermochemical reactions’ filed on 12 March 2021, US application no. PCT/US2021/022204.
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Dong, Q., Yao, Y., Cheng, S. et al. Programmable heating and quenching for efficient thermochemical synthesis. Nature 605, 470–476 (2022). https://doi.org/10.1038/s41586-022-04568-6
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