Lee EH  Kim TW  Byun SG  Seo DW  Hwang HJ  Kim HS  Ryi SK

Vol. 28,  No. 1, pp. 54-62, Mar.  2022
10.7464/ksct.2022.28.1.54

Methanol reforming Hydrogen purification Pd membrane Submarines LT-PEMFC

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This study examined the use of palladium (Pd)-composite membranes for hydrogen purification from methanol reforming gas for the operation of air independent propulsion (AIP) submarines. Since submarines utilize low-temperature polymer electrolyte fuel cells (LT-PEMFC) and one of the requirements of these fuel cells is high-purity (99.999%) hydrogen, a dense membrane without pinholes is an essential requirement for a Pd-composite membrane. A Pd-composite membrane for methanol reformed gas purification was made by electroless plating an Inconel 600 support coated with yttrium stabilized zirconia (YSZ) as a diffusion barrier layer using the blowing coating method (BCM). The membrane was tubular with a length of 450 mm and a diameter of 12.7 mm (surface area of 175 cm2). Hydrogen purification tests were carried out with simulated methanol reformed gas containing approximately 67% hydrogen at 400 ℃, a hydrogen permeation pressure of 2.5 bar, which is that of LT-PEMFCs used for AIP submarines, and a feed pressure of 25 bar. The purification tests showed that the approximately 67% hydrogen of the methanol reformed gas could be purified up to 99.999% with 80.1% hydrogen recovery when the reformed gas feeding rate was 0.53 Nm3 h-1. These results indicated that the hydrogen purification capacity of the membrane was 0.29 Nm3 h-1. After the high-pressure purification tests, the Pd-composite membrane was disassembled from the module and the surface condition and thickness were analyzed. Membrane analysis showed no membrane damage and the palladium thickness was 11 to 12 μm meaning that the plating efficiency was approximately 92%. From the purification tests and the membrane analysis, we could conclude that the developed Pd-composite membrane can be used as a hydrogen purifier for the fuel supply system of AIP submarines.