Enhanced ammonia decomposition using a Pd-Ag membrane reactor for high-purity hydrogen production

Abstract

In this study, a Pd-Ag membrane reactor (MR) integrated with a lab-synthesized ruthenium catalyst supported on La₂Ce₂O₇ was used for the efficient production and recovery of highly-pure hydrogen from ammonia decomposition. The catalyst was synthesized using solution combustion techniques, and its structure–activity relationship was thoroughly investigated through a range of advanced characterization methods, including N₂ physisorption, X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H₂-TPR), and transmission electron microscopy (TEM).

The performance of the membrane reactor was evaluated by varying the feed pressure and flow rate, using either single ammonia or a simulated outlet stream from a conventional reactor with ammonia conversions ranging from 20 % to 50 %. This configuration was designed to assess the MR ability to mitigate or prevent hydrogen back-permeation, as well as optimize membrane performance. The MR achieved ammonia conversions of up to 85 %, surpassing the thermodynamic limits typical of traditional reactors (TR). Hydrogen recovery rates reached 97 %, with purity consistently exceeding 90 %. Notably, the MR demonstrated up to 3.6 times higher ammonia conversion compared to conventional TR, highlighting its significant advantages for ammonia decomposition applications.