Compact ammonia reforming at low temperature using catalytic membrane reactors

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/Al2O3 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 H2 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.

Automated summary

This study presents an efficient method for extracting high purity hydrogen from ammonia decomposition using a catalytic membrane reactor (CMR). By reducing the thickness of the Pd membrane and adding a commercial catalyst, the CMR can handle higher ammonia flowrates without sacrificing conversion. Zeolite clinoptilolite is used to reduce ammonia impurities to the required levels. Furthermore, the durability test shows significant improvement in membrane permeability.