Transient dynamic of hydrogen permeation through a palladium membrane was studied in the present study. Three different pressure differences between the two sides of the membrane were considered; they were 3, 5 and 8atm. The experimental results indicated that the variation in the hydrogen permeation process was notable at the selected pressure differences. When the pressure difference was relatively low (i.e. 3atm), the hydrogen permeation process proceeds from a time-lag period, then to a concave up period and eventually to a concave down period. Therefore, the transient hydrogen permeation was characterized by a three-stage mass transfer process. When the pressure difference was increased to 5atm, the time-lag period disappears, thereby evolving the three-stage mass transfer process into a two-stage one. However, the concave up period withers significantly. Once the pressure difference was as high as 8atm, the transient hydrogen permeation was completely characterized by a concave down curve, yielding a single-stage mass transfer process. A quasi-steady state of hydrogen permeation was defined to evaluate the period of the transient mass transfer process. It suggested that, within the investigated conditions of operation, the time required for hydrogen permeation to reach the steady value was around or over 1h. For the low pressure difference cases, the transient period was especially long, resulting from the time-lag characteristic. Once the hydrogen permeation was in the steady state, over 80% of hydrogen could be recovered from the membrane.

Transient Dynamic of Hydrogen Permeation through a Palladium Membrane. W.H.Chen, I.H.Chiu: International Journal of Hydrogen Energy, 2009, 34[5], 2440-8