(579f) Upscaling of Facilitated Transport Membranes for Hydrogen Purification from Coal-Derived Syngas | AIChE

(579f) Upscaling of Facilitated Transport Membranes for Hydrogen Purification from Coal-Derived Syngas

Authors 

Han, Y. - Presenter, The Ohio State University
Pang, R., The Ohio State University
Ho, W., The Ohio State University
CO2-selective, amine-containing facilitated transport membranes (FTMs) are of great interest for syngas purification since high-pressure H2 can be retained upon CO2 removal. Various FTMs have shown decent chemical and thermal stability at aggressive conditions, but their CO2/H2 separation properties are largely limited by the severe carrier saturation at high syngas pressure. Herein, we report a new approach 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. Thus, 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 FTM). 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 FTM). These performances are shown in the following two figures for the Types I and II membranes, respectively. These two types of FTMs were successfully scaled up by a roll-to-roll continuous coating machine. The 14-inch wide scale-up membranes were then rolled into two prototype spiral-wound (SW) modules containing 800 and 1600 cm2 of the Type I and Type II membranes, respectively. The two SW modules were connected in series, resulting in a hybrid membrane configuration 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). Initial techno-economic analysis indicates that the hybrid membrane configuration can render a H2 recovery of 99.4% at 90% CO2 removal.