Intensifying blue hydrogen production by in situ CO₂utilisation

The current production of hydrogen, predominantly through steam methane reforming, causes up to 3% of global CO2 emissions. Since hydrogen is expected to play an increasingly important role as clean energy vector of the future, a carbon-efficient two step chemical looping process is developed to address the limitations of current H2 production technology. This process operates between 923 and 998 K and involves oxides of iron, nickel, and calcium as solid intermediates. In the first step, an H2-rich stream is produced by co-feeding steam and methane to these materials in a fixed bed, while in the second step, a CO-rich stream is produced by regenerating the materials with an air-like mixture. Proof-of-concept experiments achieved an H2 concentration of more than 65 mol% and a CO2 conversion of more than 80%. Cyclic tests indicate that carbon deposition is mitigated and the molar ratio of H2 to CO produced is approximately 2. Experimental results prove that the process concept allows circumventing the thermodynamic equilibrium constraints on conventional methane reforming for syngas production.