A Comparison of the Inhibiting Effect of CO and CO2 to Hydrogen Permeation and n-Value in Pd and Pd/Ag Membranes Prepared on Alumina Support

Abstract

The mitigation of the CO inhibition effect in palladium membranes is necessary due to its significance in the efficiency of membrane reactors and hydrogen production systems. In this work, the hydrogen separation performance of a Pd and Pd/Ag membrane both of thickness 2 μm is investigated using a mixed gas with composition (H 2 = 50%, CO = 28%, CO 2 = 10%, CH 4 = 8%, N 2 = 4%) at temperature 623 -873 K and pressure (0.05 -0.4 bar) was investigated. The component gases CO and CO 2 were observed to inhibit hydrogen permeation through the membrane and lead to deviations from Sievert's law for n values 0.55 and 0.62 for the Pd membrane and unity for the Pd/Ag membrane.For the Pd/Ag membrane, the concentration of CO in the permeate stream was reduced as a result of the addition of Ag. The effect of the component gases to hydrogen permeation was observed to be lower for the Pd/Ag membrane. Annealing the membrane in hydrogen at high temperature decreased the inhibition effect and enhanced hydrogen permeation through the membrane.