Ammonia, produced via the Haber-Bosch (HB) process, is globally the leading chemical in energy consumption and carbon dioxide emissions. In ammonia plants, hydrogen is generated by steam-methane reforming (SMR) and water-gas shift (WGS) and, subsequently, is purified for the high-pressure ammonia synthesis.
Now, a team of researchers in Greece has demonstrated how these steps can be integrated into a single BaZrO3-based protonic ceramic membrane reactor (PCMR), operating at atmospheric pressure. Hydrogen generation occurs on a Ni-composite electrode, while VN-Fe is the ammonia synthesis electrocatalyst.
Hydrogen extraction from the reforming compartment enhances the thermodynamically limited methane conversions, whereas 5%–14% of the pumped protons are converted to ammonia.
They designed an electrochemical HB process by combining this PCMR with a protonic ceramic fuel cell to recover electricity and separate nitrogen from ambient air by exploiting by-product hydrogen. This process could potentially require less energy and release less carbon dioxide emissions than its conventional counterpart—50% the CO2 and 25% the energy—holding promise for sustainable decentralized applications. A paper on their work appears in the journal Joule.
Kyriakou et al. (2019) “An Electrochemical Haber-Bosch Process,” Joule doi: 10.1016/j.joule.2019.10.006