Glass fiber entrapped sorbent for reformates desulfurization for logistic PEM fuel cell power systems

Glass fiber entrapped ZnO/SiO2 sorbent (GFES) was developed to remove sulfur species (mainly hydrogen sulfide, H2S) from reformates for logistic PEM fuel cell power systems. Due to the use of microfibrous media and nanosized ZnO grains on highly porous SiO2 support, GFES demonstrated excellent desulfurization performance and potential to miniaturize the desulfurization reactors. In the thin bed test, GFES (2.5 mm bed thickness) attained a breakthrough time of 540 min with up to 75% ZnO utilization at 1 ppm breakthrough. At equivalent ZnO loading, GFES yielded a breakthrough time twice as long as the ZnO/SiO2 sorbent; at equivalent bed volume, GFES provided a three times longer breakthrough time (with 67% reduction in ZnO loading) than packed beds of 1–2 mm commercial extrudates. GFES is highly regenerable compared with the commercial extrudates, and can easily be regenerated in situ in air at 500 °C. During 50 regeneration/desulfurization cycles, GFES maintained its desulfurization performance and structural integrity. A composite bed consisting of a packed bed of large extrudates followed by a polishing layer of GFES demonstrated a great extension in gas life and overall bed utilization. This approach synergistically combines the high volume loading of packed beds with the overall contacting efficiency of small particulates.