Experimental and simulation studies on concentration polarization in H2 enrichment by highly permeable and selective Pd membranes

Hydrogen permeability of 2.5μm palladium–silver membranes deposited on ceramic supports

“…Similar concentration polarization phenomena are well known in membrane separation process when liquid feeds are considered; indeed, also in gas separation processes, the existence of a nonnegligible concentration polarization can exist, when use is made of membranes, either polymeric or even metallic, endowed with high permeability or high selectivity [30][31][32]. In the presence of CO and of streams typical of the methane reforming process, a reduction of the effectiveness of some palladium-based membrane reactors was documented [33,34], and it was attributed to concentration polarization in the gas phase.…”

A numerical approach of conjugate hydrogen permeation and polarization in a Pd membrane tube

“…This can be explained by the lessened concentration polarization on the membrane surface as the flow rate of feed gas grows. For example, in the study of Zhang et al [23], it was reported that increasing the flow rate of feed gas can effectively weaken the negative effect of concentration polarization. The same observation has also been highlighted by Chen et al [24].…”

Effect of Feed Flow Rate of Hydrogen Mixture on Hydrogen Permeation for Flat Sheet Pd/Ag Membrane with Stagnating Flow

“…This reveals that the use of feed flow rate in the Sieverts' equation without considering the effect of H 2 flux could cause deviation from the actual H 2 permeation flux. Several researchers (12), (14)- (16) have studied the effect of feed flow rate on permeation characteristics in such condition for tubular type membrane, experimentally (14), (17) and numerically (12), (15)- (17) . They have (12), (14)- (16), (18) demonstrated the phenomena of concentration polarization, which could be clearly observed when a long tubular membrane was used.…”

“…Based on previous studies (12), (14)- (16), (18)- (20) , in the case of a high permeation ratio, the effect of feed flow rate on permeation characteristics for flat sheet Pd/Ag membrane was less explored, unlike that for the long tubular type membrane (12), (14)- (17) . Therefore, in our study, the effect of the feed flow rate on permeation characteristics for such type of membrane was investigated experimentally.…”