Study of the plasma and heating effect on hydrogen permeation through Pd0.60-Cu0.40 membrane in a micro-channel plate reactor

Abstract

The diffusion of hydrogen through palladium and palladium-copper alloys membrane have been provided the highest hydrogen selectivity and permeance. In this study the composite Pd0.60-Cu0.40 wt% membrane foil with thickness 20 μm was measured in the micro-channel plate reactor (MPR) with gap length 4.5 mm. The hydrogen permeation flux was measured at atmospheric feeding pressure for 100% H2 concentration in the temperatures range of 423–573 K under heating only and plasma-heating experiments. The plasma firing high voltage source ranges of 10–18 kV are tested. The hydrogen permeation flux and hydrogen permeability have been calculated according to Fick's and Sieverts combining laws with power exponent n-value 0.5. It was found that the maximum hydrogen flux, hydrogen permeability and Permeation rate percent of the heating only experiment at MPR heating temperature of 573 K and flow rate 0.1 l/min. In the plasma heating experiment, it was observed that the maximum hydrogen flux, hydrogen permeability, and permeation rate percent at MPR heating temperature of 573 K and plasma firing voltage of 14 kV. Also, the hydrogen permeation rate percent decreased due to the hydrogen reverse reaction even though the plasma firing voltage increased to 16 kV and 18 kV. The results also reveal that the activation energy and Pre-exponential constant factor decreased with increasing the feeding H2 flow rate while the linear regression R2 decreased with increasing H2 feeding flow rate that in the heating only experiment, in contrast, the plasma-heating experiment showed non-linearity values. A comparison between both experiments showed the hydrogen permeation flux of the plasma-heating experiment is higher than that obtained from the heating only experiment, additionally; the plasma effect increased at low hydrogen flow rates. In contrast, the energy efficiency of heating only experiment was higher than that obtained from the plasma-heating experiment due to the total energy consumption of plasma experiment is high.