High purity, self-sustained, pressurized hydrogen production from ammonia in a catalytic membrane reactor

The combination of catalytic decomposition of ammonia and in situ separation of hydrogen holds great promise for the use of ammonia as a clean energy carrier. However, finding the optimal catalyst - membrane pair and operation conditions have proved challenging. Here, we demonstrate that cobalt-based catalysts for ammonia decomposition can be efficiently used together with a Pd-Au based membrane to produce high purity hydrogen at elevated pressure. Compared to a conventional packed bed reactor, the membrane reactor offers several oper-ational advantages that result in energetic and economic benefits. The robustness and durability of the combined system has been demonstrated for > 1000 h on stream, yielding a very pure hydrogen stream (> 99.97 % H2) and recovery (> 90 %). When considering the required hydrogen compression for storage/utilization and environ-mental issues, the combined system offers the additional advantage of production of hydrogen at moderate pressures along with full ammonia conversion. Altogether, our results demonstrate the possibility of deploying high pressure (350 bar) hydrogen generators from ammonia with H-2 efficiencies of circa 75% without any external energy input and/or derived CO2 emissions.

Automated summary

The combination of catalytic decomposition of ammonia and in situ separation of hydrogen shows promise for producing clean energy. A combination of cobalt-based catalysts and a Pd-Au membrane has been found to efficiently produce high purity hydrogen. The membrane reactor offers operational advantages and energy-economic benefits compared to conventional reactors.