Prior to the H2 permeation tests, the integrity of the Pd/Al2O3
composite hollow fibre membranes was evaluated by testing
the gas-tightness of the membrane under N2 atmosphere, at
275 kPa and room temperature and using a gas-tightness
apparatus developed in house.
As the integrity of the membrane was proved, hydrogen permeation measurements
were performed using the experimental apparatus shown in
Fig. 2.
The Pd/Al2O3 composite hollow fibre membrane with
one-end sealed was glued to a stainless steel holder using
epoxy-resin (Araldite®), and then introduced in a dense
stainless steel tube with an inner diameter of 1 cm.
The whole device was then placed in a tubular furnace (CARBOLITE, MTF
10/25/130), centred and connected to inlet and outlet streams.
The permeate flow rate was monitored by bubble flow meter
and the feed pressure was adjusted using a pressure regulator
(OMEGA, PRG101-120) and monitored by a pressure gauge with
a resolution of 0.1 psi (OMEGA, DPG1000B-10G).
After purging the system meticulously, the membrane was annealed at
450 C for 2 h under hydrogen atmosphere.