(347f) Moderate Temperature H2s Removal over High Specific Surface Area Sio2 Supported Zno Sorbent: Preparation and Characterization
Zinc oxide sorbents supported on high surface area amorphous SiO2 of 100-250 micron diameter have been prepared by incipient wetness impregnation from different precursors. The calcination temperature is determined by DSC analysis. The surface area of SiO2 (190 m2/g) and ZnO/SiO2 (250 m2/g) are measured by N2-BET. The result suggests that the ZnO is well dispersed on silica surface. The XRD results indicate that the impregnated ZnO is an amorphous phase. After H2S adsorption at 400°C and regeneration in air at 550°C, the grain size increases from 4 nm for the fresh sample to 12 nm and 15 nm for 5 and 50 regeneration cycles respectively. XRD patterns of ZnO/SiO2 sorbent, commercial H2S sorbent and their spent samples are compared. The ZnS peaks in spent ZnO/SiO2 sorbent completely disappear after regeneration at 550 °C for 3 hours, while the peaks in commercial sorbent still exist after the same treatment. This result indicates that the nano-sized dispersion of ZnO significantly reduces internal mass transfer resistance for H2S adsorption and regeneration.
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