(483b) Mass Transfer Study on Glass Fiber Entrapped H2s Sorbents for Regenerable Continuous Batch Fuel Processing in Pemfc Applications

Silicon dioxide particulates of 150-250 um (dia.) were entrapped in different glass fibers of various diameters. ZnO was then loaded at 20 wt% on the silica substrate by impregnation from different precursors. A mass transfer study of the glass fiber entrapped (GFE) ZnO/SiO2 sorbent has been conducted. The internal mass transfer study on commercial sorbents, ZnO/SiO2 and GFE ZnO/SiO2 reveals that the capacity increases significantly with decreasing particulate size. The nano-dispersed nature of the ZnO ameliorates the internal mass transfer resistance which is a critical issue for commercial sorbents. ZnO/SiO2 and GFE ZnO/SiO2 offer a high capacity at 92% of the theoretical capacity, and the capacity of GFE sorbent at 1% breakthrough is twice that of commercial H2S sorbents with the equivalent ZnO mass loading. The external mass transfer study on ZnO/SiO2 and GFE ZnO/SiO2 shows that the breakthrough capacity increases drastically at low face velocities up to 5 cm/s. A further increase in face velocity does not show significant improvement in breakthrough capacity. At the same face velocity, the micro-sized glass fiber media enhances the external mass transfer, and breakthrough time of GFE ZnO/SiO2 sorbent is twice that of ZnO/SiO2. From the mass transfer study of GFE ZnO/SiO2, it is clear that the combination of the microfiber media and nano-dispered ZnO on SiO2 improves both the internal and external mass transfer. This combination offers an ideal solution for trace H2S removal in onsite fuel processor for H2 production from gasoline or diesel fuels containing sulfur.