Synthesis of porous ZnO based materials using an agarose gel template for H2S desulfurization

Abstract

This work describes the synthesis and characterization of pure ZnO and Ni-doped ZnO materials using agarose gel as a template for H₂S desulfurization. H₂S gas is not only harmful to the environment, but also corrosive to metals and poisonous to fuel reformer and fuel cell catalysts. Removal of H₂S is an important step in fuel processing technology. This synthetic approach resulted in highly porous network ZnO based sorbent materials. The phase structure and morphology of these two materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer, Emmett and Teller (BET) surface area measurements, and mercury porosimetry. The H₂S desulfurization performance of the as-synthesized ZnO and Ni-doped ZnO materials versus commercial ZnO was studied in a simulated fuel processing operation at 400 °C with an initial H₂S concentration of 400 ppmv. It is shown that the sulfur adsorption capacity is greatly affected by the size and morphology of the particles. Desulfurization analysis revealed that commercial ZnO exhibits a low saturation capacity of 245 mg S per g while as-synthesized ZnO has a capacity of 457 mg S per g. Notably, when ZnO was doped with 4 wt% Ni, the sorbent capacity increased still further to 730 mg S per g.