Effect of the presence of light hydrocarbon mixtures on hydrogen permeance through Pd–Ag alloyed membranes

• Pd membrane permeation in presence of propene.
• Coke formation on the membrane.
• Effect of gas composition and temperature.
• Change of membrane efficiency along time.

The production of light olefins by alkane dehydrogenation is limited by the thermodynamic equilibrium. The use of membrane reactors for this process enhances alkane conversion by a selective removal of hydrogen from the reaction media. This hydrogen removal results in an equilibrium shift towards the production of olefins. However, hydrogen permeance through Pd-based membranes may be affected by the presence of light olefins. This work evaluates the effect of the composition of propane/propylene mixtures on the hydrogen permeation through Pd–Ag alloyed membranes for propane dehydrogenation. It has been observed that the transient hydrogen permeation decreases in the presence of C3 species due to coke deposition over the Pd–Ag layer. The permeation decrease has been characterized and quantified as a function of propane/propylene contents in the feed gas and of operation temperature.