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Programmable heating and quenching for efficient thermochemical synthesis


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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Fig. 1: Comparison between our PHQ method and conventional continuous heating using a CH4 pyrolysis model reaction.
Fig. 2: Operation of the PHQ technique.
Fig. 3: The utility and advantages of our PHQ technique.
Fig. 4: NH3 synthesis by PHQ under ambient pressure.

Data availability

The data that support the findings of this study are available within this article and its Supplementary Information. Further data are available from the corresponding authors on reasonable request. Source data are provided with this paper.

Code availability

The code used for active learning has been deposited in the Code Ocean repository (ref. 41).


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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).

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Authors and Affiliations



L.H., Q.D. and Y.Y. came up with the design concept. Q.D. and S.C. designed the reactor and collected the data for CH4 pyrolysis. Q.D., Y.Y. and J.G. collected the data for NH3 synthesis. K.A., H.E.T. and D.G.V. carried out the simulation for CH4 pyrolysis and the energy cost calculation. S.S. and Y.W. conducted the active learning. Q.D. and X.W. performed the temperature measurements. Y.P., C.Z. and B.Y. carried out the modelling for the temperature profile of the gas molecules. J.G. collected the digital images. Q.D. and Y.Y. conducted the spectroscopic and microscopic analysis. K.A., D.G.V., H.Z. and Y.J. carried out the simulation for NH3 synthesis. I.G.K. helped analyse the overall results. L.H., Q.D., Y.Y. and A.H.B. collectively wrote the paper, together with input from all authors. L.H., D.L. and D.G.V. supervised the project. All authors discussed the results and contributed to the final manuscript.

Corresponding authors

Correspondence to Dionisios G. Vlachos, Dongxia Liu or Liangbing Hu.

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Competing interests

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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Nature thanks the anonymous reviewers for their contribution to the peer review of this work.

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This file contains Supplementary Methods; Supplementary Tables 1–3; Supplementary Discussions 1–15 and Supplementary References.

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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).

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