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538e

Development of Cathode Air Filters for PEM Fuel Cell Using Microfibrous Entrapped Sorbents

Abhijeet G. Phalle1, Vivekanand Gaur1, and Bruce Tatarchuk2. (1) Department of Chemical Engineering, Auburn University, 230 Ross Hall, Auburn, AL 36849, (2) Chemical Engineering, Auburn University, 230 Ross Hall, Auburn, AL 36849

The performance of Proton Exchange Membrane Fuel Cell (PEMFC) is degraded significantly as a result of poisoning of cathode catalyst by airborne contaminants, in particular SO2 and NOx in trace levels. In the literature, it has been suggested that the best method for addressing fuel cell contamination is by the inclusion of adsorptive filtration with a cathode air filter. This work thus aims at the development of adsorptive cathode air filters, mainly to remove SO2 because of its irreversible effects on PEMFC. Two types of sorbents were prepared; an alumina support impregnated with different transition metal (Mn, Fe, Ni, Cu and Zn) oxides and inorganic chemicals (KOH and KMnO4). The adsorption capacity of these sorbents was investigated in a tubular packed column with inlet SO2 concentration of 70 ppm in air under dry as well as moist (50% relative humidity) conditions at room temperature. At identical loadings,among all metal oxide based sorbents, MnO2/Al2O3 showed the highest saturation capacity.In contrary, the results demonstrated that the 10% (w/w) KOH/ Al2O3 had almost double breakthrough capacity for SO2 as compared with that of 10% (w/w) MnO2/Al2O3.

A bi-component polymer fibers-entrapped KOH/Al2O3 sorbent (PFES) is designed for SO2 removal from air. Due to the microfibrous media and supported sorbent design, PFES demonstrated superior SO2 removal performance as compared with a packed bed. At equivalent (10 wt%) KOH loading, the PFES yielded 50% higher breakthrough capacity than that for KOH/Al2O3 sorbent in the packed bed. This is attributed to the high contact efficiency of small particulates, high KOH utilization, and high accessibility of KOH. The other sorbents including KMnO4/Al2O3 and MnO2/Al2O3 are also being entrapped in microfibrous sheets and investigated for their SO2 removal efficiency. The use of these novel microfibrous entrapped sorbents provides reduced external mass transfer resistance enhancing adsorption rate. Similar entrapped sorbents will be developed for the air contaminants other than SO2 including NOx and VOCs.