(85d) Compact Delivery of UHP Hydrogen from Ammonia Decomposition Using Catalytic Membrane Reactors

The deployment of fuel cell electric vehicles is constrained by the paucity of hydrogen fueling stations and price, which is dominated by the costs of hydrogen storage and transportation. With more hydrogen per volume than liquid H₂ and an extensive distribution infrastructure in place, ammonia is a promising vector for efficient hydrogen distribution. In this talk, we describe the development of catalytic membrane reactor (CMR) technology for process-intensified delivery of high purity H₂ from ammonia cracking. The CMR integrates state-of-the-art catalysts with thin Pd –based metal membranes. We have developed a detailed axisymmetric model that captures the reactor performance with high fidelity, and this is used for the analysis and design of these systems. High volumetric productivity is obtained by combining highly active catalysts with an elevated transmembrane driving force to maximize conversion and hydrogen recovery, respectively. Ammonia decomposition rate is inhibited by both H₂ adsorption and reverse reaction, but the efficient removal of H₂ in a CMR enables temperature reductions by up to 200 ºC and decreases catalyst loading requirements by a factor of 2. Commercial zeolite adsorbents are identified that reduce the ammonia in the hydrogen permeate stream from ~1000 ppm to below detectable limits (sub ppm) as required by commercial fuel cells.