Hydrogen Permeation through Pd82Ag18/Al2O3 Membrane in Steady State and Dynamic Condition: The Effect of N2 and CO in the Feed Gas

• Main Author: Zulfikar Irriyanto (13014043), Mardika Firlina (13014116), Miqdar
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/28932
• Institution: Institut Teknologi Bandung

<p align="justify">Hydrogen separation from gas mixture using palladium (82%w) silver (18%w) alloy membrane with Al2O3 support can increase hydrogen permeation flux. The problem that occurs in the separation process using the membrane was the decrease in H2 recovery over time due to the presence of other compounds which blocks the active surface of the membrane. Increasing H2 recovery can be done by operating the separation under forced unsteady state condition. The purpose of this study was to examine the inhibitory effects of N2 and CO on H2 recovery using Pd82Ag18/Al2O3 membrane under steady state and forced unsteady state conditions. The parameter observed was H2 recovery. <br /> This study used Pd82Ag18 membrane with 20.2 &#956;m thickness, 2 mm Al2O3 support thickness, 7.5 mm diameter, and 75 mm length. The feed used was a mixed gas combination of H2, N2, and CO. Ar gas was added to the feed gas to keep gas residence time in the membrane constant and N2 sweep gas was used to increase the driving force of H2 permeation. The operating conditions of this study were 350ºC and atmospheric pressure. The variation used in the steady state condition was feed gas composition while the variation in the forced unsteady state condition is H2 feed flow rate with 30, 60, and 300 seconds switching time (ST). <br /> Permeability coefficient of membrane Pd82Ag18/Al2O3 in this study was 2.57x10-4 mol H2 m-1 h-1 kPa-0,5 which was bigger compared to membrane permeability coefficient Pd100 1.59x10-4 mol H2 m-1 h-1 kPa-0,5 (Chen and Ciu, 2009). The H2 recovery with various feed gas composition were 33.4% (H2:N2 120:60), 29,8% (H2:N2 120:75), and 23,1% (H2:N2 120:90). Whereas in the same feed composition for H2:CO, H2 recovery was only 21.8% (H2:CO 120:60), 19.9% (H2:CO 120:75), and 18.7% (H2:CO 120:90). The decreasing H2 recovery were caused by several conditions such as concentration polarization and competitive adsorption. During forced unsteady state conditions, H2 recovery was examined in three regimes with different switching time. The highest H2 recovery was 24.5% and achieved during quasy steady state regime at ST 300 seconds. The H2 recovery during forced unsteady state condition was found higher than H2 recovery during steady state condition that was only 12.1%. These results prove the hypothesis that increasing H2 recovery can be done by operating the separation under forced unsteady state condition.<p align="justify"> <br />