Pd–Pt/YSZ composite membranes for hydrogen separation from synthetic water–gas shift streams

The influence of heat treatment on the thermal stability of Pd composite membranes

“…The average hydrogen flux and percent recovery dropped by 8% suggesting slight inhibition by the presence of carbon. Flux inhibition due to the presence of carbon species was also observed by Lewis et al [27] to a larger extent at lower temperatures (o450°C). Despite this slight flux inhibition, the hydrogen permeate purity was very stable at $ 99.7% over the course of testing for Pd-3, which was heat treated at 650°C for 144 h prior to mixed-gas testing.…”

“…5, an equimolar mixture of hydrogen and nitrogen (50:50) was first introduced to establish a baseline for subsequent experiments to assess common operating issues such as concentration polarization and flux inhibition (upon exposure to carbon species) [7,27]. The average hydrogen flux under this 50:50 mixture was 0.43 mol/m 2 /s with an average hydrogen recovery of 81% at 550°C, 1.03 MPa feed pressure (permeate at local ambient conditions) and a space velocity of 387 h À 1 , as shown in Table 2.…”

Recent developments in membranes for efficient hydrogen purification

“…Though dense metallic membranes possess an extremely high selectivity towards H 2 , the corresponding low gas permeance hampers their practical application. Development of composite membranes in 13 which a thin metallic layer is deposited on a porous polymeric or inorganic support, has been considered as an effective method to improve gas permeance of dense metallic membranes [22]. Currently, there are diverse dense metallic layer deposition technologies available, such as chemical vapor deposition, physical vapor deposition, electroplating and electroless plating.…”

Preparation and characterization of inorganic membranes for hydrogen separation

“…Palladium (Pd) [4,9], platinum (Pt) [9] and their alloys are the ideal membranes applied for high purity hydrogen production from mixed gas streams even though these metals are expensive [4,9,10]. Pd-based membranes are attractive for membrane reactor applications because dense Pd is highly permeable to hydrogen and if properly configured can offer better thermal stability and selectivity than polymer and microporous membranes [9].…”

“…Palladium (Pd) [4,9], platinum (Pt) [9] and their alloys are the ideal membranes applied for high purity hydrogen production from mixed gas streams even though these metals are expensive [4,9,10]. Pd-based membranes are attractive for membrane reactor applications because dense Pd is highly permeable to hydrogen and if properly configured can offer better thermal stability and selectivity than polymer and microporous membranes [9]. Transport of hydrogen through dense Pd membranes follows the solution diffusion mechanism where only hydrogen is transported resulting in high purity (99.9999%), but have been limited in commercialization due to issues which include support quality, surface poisoning due to carbon species, hydride formation, and irreversible damage caused by bulk sulfide formation [9,11,12].…”