Compact ammonia reforming at low temperature using catalytic membrane reactors

Abstract

Ammonia is a leading carrier for the storage and transport of renewable hydrogen, but its deployment requires scalable technologies for efficient decomposition and purification. In this work, we report on the efficient delivery of high purity hydrogen from ammonia decomposition using a catalytic membrane reactor (CMR). Improvements to the electroless plating process reduced the Pd membrane thickness by >35%, resulting in commensurate increases in hydrogen permeance without sacrificing selectivity. To increase throughput a commercial Ru/Al 2 O 3 catalyst was added to the lumen, and the CMR could process ammonia flowrates 10–50 times higher than an equivalent packed bed reactor while maintaining the same level of conversion. It is shown that the earth-abundant zeolite clinoptilolite could reduce ammonia impurities in the permeated H 2 to the levels required by PEM fuel cells (<25 ppb). Performance increased significantly across a >500-h durability test due to improvements in membrane permeability. The results show that CMRs are a viable technology for distributed production of hydrogen from ammonia. • Ultrasound-assisted plating enabled reduced thickness and defect density • CMR volumetric productivity >50 mol H 2 /m 3 *s and >500 h stability • CMR displays 10–20X higher throughput than equivalent PBR for NH 3 decomposition • Demonstrate ability to recycle, reuse CMR supports • Clinoptilolite adsorbent shown to reduce residual [NH 3 ] to <25 ppb