Tailoring Pd-membranes prepared by continuous-flow Electroless Pore-Plating: Role of hydrazine concentration and solution flow rate

This work investigates the influence of two key synthesis parameters (hydrazine concentration and solution flow rate) on the structure and hydrogen permeation performance of planar Pd-membranes prepared by continuous-flow Electroless Pore-Plating (cf-ELP-PP). A systematic experimental study was performed to identify operating conditions enabling the fabrication of thin, defect-free, and mechanically stable Pd-films. The results demonstrate that a hydrazine concentration of 0.20 M combined with a solution flow rate of 12 mL min −1 leads to homogeneous Pd-films with an average thickness of ∼9 μm, exhibiting complete ideal H 2 -selectivity and permeance values of 3.5-4.3·10 −4 mol m −2 s −1 ·Pa −0.5 at 400 °C. Reproducibility tests confirmed deviations within ±20% among independently fabricated samples. Beyond single-gas evaluation, the optimized membrane maintained complete H 2 -selectivity under mixed-gas conditions (H 2 /N 2 , H 2 /CO 2 and H 2 /CO) and demonstrated stable performance over 300 h of operation, including reversible inhibition in the presence of CO through mil air regeneration cycles. Compared with alternative fabrication routes reported in the literature, the optimized cf-ELP-PP process provides a simple, reproducible and scalable strategy for the development of high-performance Pd-membranes suitable for hydrogen purification and membrane-reactor applications. • cf-ELP-PP optimization yields thin, defect-free Pd-films with complete H 2 selectivity. • Hydrazine concentration and flow rate govern Pd-film structure and performance. • Optimal synthesis conditions (0.20 M, 12 mL min −1 ) generate ∼9 μm Pd-films. • Membranes show H 2 -permeance of 3.5-4.3·10 −4 mol m −2 s −1 Pa −0.5 at 400 °C. • Reproducibility confirmed within ±20% in thickness and hydrogen permeance.