(147f) Cathode Air Filtration for PEM Fuel Cell Using Microfibrous Entrapped Sorbents

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 SO₂and NO_x in trace levels. Removal of air contaminants by adsorptive filtration is economical and easier way to mitigate cathode air contamination .This work thus aims at designing of adsorptive air filters having high adsoprtion capacity and high contacting efficiency for removal of SO₂ along with lower pressure drop across a filter. Two types of alumina-supported sorbents were prepared and tested for SO₂ removal; one impregnated with oxides of transition metals (Mn, Fe, Ni, Cu and Zn) and other one impregnated with inorganic chemicals (KOH and KMnO₄. MnO_x/Al₂O₃ prepared using MnSO₄ as a precursor showed the highest saturation and breakthrough capacity over wide range of RH. Particularly, it showed 60% higher saturation capacity than commercial KMnO₄/Al₂O₃ sorbent.

For packed beds,use of smaller size particles give high single pass removal effciency but generally at the expense of higher pressure drop, which increases parasitic power loss. Microfibrous media (MFM) prepared by entrapping micron size particles in sinter-locked network of polymer fibers have shown to give high contacting efficiency with lower pressure drop. Different filter configurations such as composite bed , pleated filters can be prepared with the use of MFM and their comparison with the conventional packed bed gives better insight into optimal design of filter .Composite bed consisting of packed bed with large size particles (~1mm) of selected sorbent followed by polishing layer of MFM was prepared and its performance was compared with packed bed. Due to use of smaller particles in polisher layer, composite bed demonstrated superior SO₂ removal performance as compared with a packed bed.