(278a) Integrated Facilitated Transport Membrane Modules for Highly Selective Syngas Purification and Carbon Capture
AIChE Annual Meeting
2022
2022 Annual Meeting
Separations Division
Membranes for CO2 Capture I
Tuesday, November 15, 2022 - 8:00am to 8:21am
Amine-containing facilitated transport membranes (FTMs) are of great interest for syngas purification. Herein, we report a new method to enhance the CO2 permeance by manipulating the steric hindrance of the amine carrier. A series of α-aminoacids with different alkyl or hydroxyethyl substituents were deprotonated by 2-(1-piperazinyl)ethylamine, resulting in nonvolatile aminoacid salt carriers with different degrees of steric hindrance. In the presence of moisture, a bulkier alkyl substituent increased the steric hindrance and hence destabilized the carbamate adduct to afford bicarbonate through hydrolysis. This drastically increased the chemisorption of CO2. The enhanced CO2 solubility significantly mitigated the carrier saturation, and an unprecedented CO2/H2 selectivity greater than 125 was demonstrated at 107°C and 13.8 bar of CO2 partial pressure (Type I). As the CO2 partial pressure reduced to 1.1 bar, a less hindered amine yielded a higher reactive diffusivity of CO2, resulting in a CO2 permeance of 217 GPU with a selectivity greater than 268 (Type II). These two types of FTMs were successfully scaled up by a roll-to-roll continuous coating machine. The 14Ⳡwide scale-up membranes were then rolled into two prototype spiral-wound modules containing 800 and 1600 cm2 of the Type I and Type II membranes, respectively. At 90% CO2 capture, the Type I and Type II modules achieved a CO2 purity of ca. 95%, but the H2 recoveries were only 98.2% and 97.1%, respectively. However, when the two modules were connected in series with the Type I membrane treating the syngas near the feed inlet (i.e., high CO2 partial pressure) and the Type II membrane separating the gas in the proximity of the retentate outlet (i.e., low CO2 partial pressure), the H2 recovery was improved to 99.3%. The integrated membrane array also demonstrated 200-h stability under simulated syngas.