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 NO_x 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) at varied loadings. 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. The SO₂ adsorption capacity of the screened sorbents at saturation level decreased in a sequence as: KMnO₄ (5%)/Al₂O₃ > MnO₂ (10%)/Al₂O₃ > KOH (10%)/Al₂O₃. 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 NO_x and VOCs.