Effect of Pd–Ru alloy membrane thickness on H2 flux from steam reforming products

Abstract

The influence of the thickness of a Pd–Ru alloy membrane on the H₂ flux from binary mixtures containing about 5 and 20% CO, CO₂, CH₄, and steam has been studied. It has been shown that with a decrease in the membrane thickness from 30 to 10 μm, the negative influence of these impurities on the H₂ flux increases. In experiments with pure H₂, it has been established that a decrease in the membrane thickness does not affect the nature of the rate-limiting step in the H₂ flow mechanism. The values for the effective activation energy of the H₂ permeability of the 30- and 10-μm membranes are 13.6 and 23.4 kJ/mol, respectively. A mathematical model describing the flow of hydrogen from binary mixtures through membranes of various thicknesses with varying temperature and pressure is proposed.