Scaling up a Protonic Membrane Reformer for Lower-Carbon Hydrogen Production

Abstract A protonic membrane reformer (PMR) was used to produce pure, pressurized hydrogen via steam reforming of methane combined with electrochemical hydrogen separation and compression, with co-production of a concentrated stream. The pilot unit comprises five 36-cell protonic membrane stacks connected in parallel. The tubular protonic cells are composed of porous Ni-BZCY electrodes and a thin, dense BZCY electrolyte membrane layer that carries out the hydrogen separation and compression. First, to investigate the performance stability and durability of the pilot unit, a long-term test was run for 800 hours. Stable methane conversion of higher than 99% was attained during the long-term test while an average hydrogen purity of 99.76% was obtained. Furthermore, the hydrogen recovery was found to vary between 95% and 99% under different current inputs. Then, a parametric study was then done to investigate the effects of varying the pressure differential, feed pressure, and methane feed flow rates. The pilot unit provided high methane conversions and pure, compressed hydrogen (10 barg) while maintaining stable performance during long-term testing and evaluation for more than 4000 hours. Furthermore, commercial simulation software (Aspen Plus V12.1) was used to develop a model of the PMR. The results of the model were validated with in-house pilot-scale PMR experimental data and good agreement was observed between the model output and experiments, which suggests the model will be useful for optimizing the PMR design as well as its operating conditions. Based on these results, a 50 kg-H2/day demonstration unit was designed, fabricated, and tested to produce lower-carbon hydrogen from methane.