Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Overcoming chemical equilibrium limitations using a thermodynamically reversible chemical reactor


All real processes, be they chemical, mechanical or electrical, are thermodynamically irreversible and therefore suffer from thermodynamic losses. Here, we report the design and operation of a chemical reactor capable of approaching thermodynamically reversible operation. The reactor was employed for hydrogen production via the water–gas shift reaction, an important route to ‘green’ hydrogen. The reactor avoids mixing reactant gases by transferring oxygen from the (oxidizing) water stream to the (reducing) carbon monoxide stream via a solid-state oxygen reservoir consisting of a perovskite phase (La0.6Sr0.4FeO3-δ). This reservoir is able to remain close to equilibrium with the reacting gas streams because of its variable degree of non-stoichiometry and thus develops a ‘chemical memory’ that we employ to approach reversibility. We demonstrate this memory using operando, spatially resolved, real-time, high-resolution X-ray powder diffraction on a working reactor. The design leads to a reactor unconstrained by overall chemical equilibrium limitations, which can produce essentially pure hydrogen and carbon dioxide as separate product streams.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it


Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Thermodynamic reversibility in a WGS reactor.
Fig. 2: Conversion, reactor performance measure (K*) and outlet mole fractions (real and modelled) versus cycle number show that equilibrium limitations have been overcome.
Fig. 3: Representative shifts in 2θ peak positions and local oxygen content of the LSF versus reactor position showing changes in lattice parameter and oxygen content are a function of axial position.

Data availability

Data supporting this publication are openly available under an ‘Open Data Commons Open Database License’. The data, with additional metadata, are available at


  1. Dincer, I. & Cengel, Y. A. Energy, entropy and exergy concepts and their roles in thermal engineering. Entropy 3, 116–149 (2001).

    Article  Google Scholar 

  2. Dunbar, W. R. & Lior, N. Sources of combustion irreversibility. Combust. Sci. Technol. 103, 41–61 (1994).

    Article  CAS  Google Scholar 

  3. Dudukovic, M. P. Frontiers in reaction engineering. Science 325, 698–701 (2009).

    Article  CAS  Google Scholar 

  4. Thursfield, A., Murugan, A., Franca, R. & Metcalfe, I. S. Chemical looping and oxygen permeable ceramic membranes for hydrogen production—a review. Energy Environ. Sci. 5, 7421–7459 (2012).

    Article  CAS  Google Scholar 

  5. Adanez, J., Abad, A., Garcia-Labiano, F., Gayan, P. & de Diego, L. F. Progress in chemical-looping combustion and reforming technologies. Prog. Energy Combust. Sci. 38, 215–282 (2012).

    Article  CAS  Google Scholar 

  6. Fan, L. S. in Chemical Looping Systems for Fossil Energy Conversions 241–249 (Wiley-AIChE, 2010).

  7. Lyngfelt, A., Leckner, B. & Mattisson, T. A fluidised-bed combustion process with inherent CO2 separation; application of chemical-looping combustion. Chem. Eng. Sci. 56, 3101–3113 (2001).

    Article  CAS  Google Scholar 

  8. Richter, H. J. & Knoche, K. F. Reversibility of combustion processes. ACS Symp. Ser. 235, 71–85 (1983).

    Article  CAS  Google Scholar 

  9. Anhedena, M. & Svedberga, G. Exergy analysis of chemical-looping combustion systems. Energy Convers. Manag. 39, 1967–1980 (1998).

    Article  Google Scholar 

  10. US Department of Energy Hydrogen and Fuel Cell Technical Advisory Committee Report of the Hydrogen Production Expert Panel (US Department of Energy, 2013);

  11. Lu, G. Q. et al. Inorganic membranes for hydrogen production and purification: a critical review and perspective. J. Colloid Interface Sci. 314, 589–603 (2007).

    Article  CAS  Google Scholar 

  12. Giessler, S., Jordan, L., da Costa, J. C. D. & Lu, G. Q. Performance of hydrophobic and hydrophilic silica membrane reactors for the water gas shift reaction. Sep. Purif. Technol. 32, 255–264 (2003).

    Article  CAS  Google Scholar 

  13. Basile, A., Criscuoli, A., Santella, F. & Drioli, E. Membrane reactor for water gas shift reaction. Gas Sep. Purif. 10, 243–254 (1996).

    Article  CAS  Google Scholar 

  14. Noor, T., Gil, M. V. & Chen, D. Production of fuel-cell grade hydrogen by sorption enhanced water gas shift reaction using Pd/Ni-Co catalysts. Appl. Catal. B 150, 585–595 (2014).

    Article  Google Scholar 

  15. Jang, H. M., Kang, W. R. & Lee, K. B. Sorption-enhanced water gas shift reaction using multi-section column for high-purity hydrogen production. Int. J. Hydrogen Energy 38, 6065–6071 (2013).

    Article  CAS  Google Scholar 

  16. Jang, H. M., Lee, K. B., Caram, H. S. & Sircar, S. High-purity hydrogen production through sorption enhanced water gas shift reaction using K2CO3-promoted hydrotalcite. Chem. Eng. Sci. 73, 431–438 (2012).

    Article  CAS  Google Scholar 

  17. Harrison, D. P. Sorption-enhanced hydrogen production: a review. Ind. Eng. Chem. Res. 47, 6486–6501 (2008).

    Article  CAS  Google Scholar 

  18. Ortiz, A. L. & Harrison, D. P. Hydrogen production using sorption-enhanced reaction. Ind. Eng. Chem. Res. 40, 5102–5109 (2001).

    Article  CAS  Google Scholar 

  19. Balasubramanian, B., Ortiz, A. L., Kaytakoglu, S. & Harrison, D. P. Hydrogen from methane in a single-step process. Chem. Eng. Sci. 54, 3543–3552 (1999).

    Article  CAS  Google Scholar 

  20. Kathe, M. V., Empfield, A., Na, J., Blair, E. & Fan, L.-S. Hydrogen production from natural gas using an iron-based chemical looping technology: thermodynamic simulations and process system analysis. Appl. Energy 165, 183–201 (2016).

    Article  CAS  Google Scholar 

  21. Mizusaki, J., Yoshihiro, M., Yamauchi, S. & Fueki, K. Nonstoichiometry and defect structure of the perovskite-type oxides La1-xSrxFeO3-δ. J. Solid State Chem. 58, 257–266 (1985).

    Article  CAS  Google Scholar 

  22. Sogaard, M., Hendriksen, P. V. & Mogensen, M. Oxygen nonstoichiometry and transport properties of strontium substituted lanthanum ferrite. J. Solid State Chem. 180, 1489–1503 (2007).

    Article  CAS  Google Scholar 

  23. Rydén, M. et al. Novel oxygen-carrier materials for chemical-looping combustion and chemical-looping reforming; LaxSr1-xFeyCo1-yO3-δ perovskites and mixed-metal oxides of NiO, Fe2O3 and Mn3O4. Int. J. Hydrog. Energy 2, 21–36 (2008).

    Google Scholar 

  24. Murugan, A., Thursfield, A. & Metcalfe, I. S. A chemical looping process for hydrogen production using iron-containing perovskites. Energy Environ. Sci. 4, 4639–4649 (2011).

    Article  CAS  Google Scholar 

  25. Hodeau, J.-L. et al. Nine-crystal multi-analyser stage for high resolution powder diffraction between 6 and 40 keV. Proc. SPIE 3348, 353–361 (1998).

    Article  Google Scholar 

Download references


C.R.T. and C.d.L. thank EPSRC for funding via a doctoral training award. The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC grant agreement no. 320725 and from the EPSRC via grants EP/G012865/1, EP/J016454/1, EP/K029649/1, EP/P007767/1 and EP/P024807/1. The authors thank A. Fitch, C. Giacobbe, M. Coduri and O. Grimaldi at ESRF for help with XRD and T. Ingham, IGI Systems, for constructing the custom flow system and furnace. The authors also thank A. Coelho for developments in Topas to enable analysis of the multiple X-ray data sets produced, and B. Ladewig for help in producing the video.

Author information

Authors and Affiliations



I.S.M. conceived the overall idea, secured funding and managed the work. I.S.M. and J.S.O.E. wrote the main text. I.S.M., B.R., W.H., C.d.L. and J.S.O.E. were responsible for the data analysis, modelling and interpretation. B.R., C.De., C.d.L., C.Du., F.R.G.-G., C.-M.M., E.I.P. and C.R.T. performed the experiments.

Corresponding author

Correspondence to Ian S. Metcalfe.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary information

Supplementary Methods, Supplementary Analysis, Supplementary Results, Supplementary Modelling, Supplementary Figs. 1–10, Supplementary Tables 1–6

Supplementary Video 1

A video that shows the principle of operation of the chemical memory reactor

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Metcalfe, I.S., Ray, B., Dejoie, C. et al. Overcoming chemical equilibrium limitations using a thermodynamically reversible chemical reactor. Nat. Chem. 11, 638–643 (2019).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing