Effect of Operating Conditions on PAHs Emission from a Single H2-O2 PEM Fuel Cell

ABSTRACT

This study investigates the emissions of polycyclic aromatic hydrocarbons (PAHs) from a single hydrogen-oxygen proton exchange membrane (PEM) fuel cell (FC) under different flowrates, temperatures, sampling periods, and membrane-electrode assemblies (MEAs). The results show that Nap, PA, BeP, FL, Pyr, BbC, Ant, and Flu were dominant in anode and cathode emissions of the single PEMFC under different operating conditions. The emission concentrations of Total-PAHs and Total-BaP equivalent carcinogenic potency (BaP_eq) were lower from the anode than from the cathode emission. Moreover, the concentrations of molecular-weight (MW) classified PAHs were in the order low (L) MM- > high (H) MW- > middle (M) MW-PAHs. When the anode/cathode gas flowrates were greater or smaller than 52/35 sccm but at the same sampling volume, the emission concentrations of Total-PAHs and Total-BaPeq increased. The concentration of Total-PAHs decreased but the mass of Total-PAHs increased with the increase of sampling time. However, 64% and 82% of PAH mass were emitted within 12 and 24 h, respectively, based on 36 h sampling at anode/cathode gas flowrates = 52/35 sccm. The concentrations of Total-PAHs or Total-BaP_eq of anode or cathode emission were slightly higher at 90°C than at 65°C.

The performances of commercial MEAs were in the order SGL < E-TEK < GORE. Nevertheless, the concentrations of anode or cathode emission Total-PAHs or Total-BaP_eq for the PEMFC using different MEAs followed the order GORE > E-TEK2 > E-TEK > SGL, while the sums of anode and cathode Total-PAHs emission factors varied with the order SGL > E-TEK > E-TEK2 > GORE (13.3 ± 0.55, 11.5 ± 0.21, 7.91 ± 0.47, and 3.17 ± 0.22 µg g^–1-MEA, respectively). When using the (lab-made) E-TEK2 as the MEA of PEMFC, the PAH profiles of anode and cathode emission gases were similar to those of some carbon materials.