Facile Regeneration Vitreous Microfibrous Entrapped Supported ZnO Sorbent with High Contacting Efficiency for Bulk H2S Removal from Reformate Streams in Fuel Cell Applications

In this study, a microfibrous carrier consisting of 3 vol.% of 8 µm (diameter) glass fibers is used to entrap 45 vol.% of 150 to 250 µm (diameter) SiO2 support particulates. ZnO is then nanodispersed onto the support by impregnation at the loading of 17 wt.%. At equivalent bed volumes, ZnO/SiO2-entrapped materials provide twofold longer breakthrough times for H2S (with a 67% reduction in sorbent loading) compared with packed beds of 1 to 2 mm commercial extrudates. Five-log reductions in H2S concentration with up to 75% ZnO utilization at breakthrough are achieved. H2S concentrations from 60 to 2000 parts per million in volume (ppmv) can be reduced to as little as 0.6 ppmv at 400°C in 30% H2O at a face velocity of 1.7 cm/s for layers as thin as 1.0 mm. At 500 to 600°C, ZnO/SiO2-entrapped materials provide much higher regenerability in air than do 1 to 2 mm commercial extrudates. The use of glass fibers permits greater than 50 regeneration cycles.[PUBLICATION ABSTRACT]