Investigation of molten carbonate electrolysis cells performance for H2 production and CO2 capture

Abstract

Molten carbonate electrolysis cells have recently gained interest for the sustainable production of H2 or syngas to substitute fossil fuels. However, they can be also used for CO2 sequestration, as they pump it from one electrode inlet to the opposite electrode outlet. Thus, they can easily be applied to segregation of CO2 from H2 based fuels while also increasing the fuel heat of combustion for example after a steam reforming reactor.To explore the use of molten carbonate electrolysis cell for this application, in this work the authors investigate the performance of the cell under different operating conditions in term of both operating temperature and fuel electrode gas composition. Polarization curves, gas crossover and electrochemical impedance spectroscopy are used to evaluate specific issues (high electrolyte losses due to water and temperature) or benefits (excess of H2O in regard to CO2 that allows for higher CO2 capture rate). After, a series of long-term tests at −150 mA cm−2 and 650 °C are performed to demonstrate long term stability. In particular, before electrolyte loss made the performance unstable, different cells are operated for about 1000 h with an average voltage of about 1.14 V demonstrating also the repeatability of such tests.