Low Temperature H₂S Removal with Metal-Doped Nanostructure ZnO Sorbents: Study of the Origin of Enhanced Reactivity in Cu-Containing Materials

Abstract

Sulfidation of pure and metal-doped ZnO nanostructure sorbents (M 0.03 Zn 0.97 O, M = Fe, Co, Ni, Cu) was studied in order to clarify the effect of metal on the transformation kinetics at 200À350 °C. The solids were prepared by coprecipitation from metal nitrate solution followed by calcination at 400 °C. Reaction with H 2 S was studied by thermal gravimetric analysis (TGA) using a gas mixture containing 0.2 vol % H 2 S in equimolar H 2 ÀN 2 . It was found that at 350 °C the TGA sulfidation profiles of all studied samples are similar, with the interface reaction being the main rate-determining step. After lowering the temperature to 250 °C the transformation of Cu 0.03 Zn 0.97 O continues to be controlled by the interface reaction with only a slightly decreased rate. In contrast, for all other samples the diffusion resistance appears, provoking a significant drop of their transformation rates. This finding shows that during sulfidation of Cu-doped ZnO the diffusion is faster than for all other sorbents. The same effect was observed for the sample prepared by impregnation of ZnO powder and containing supported Cu species. In order to understand the origin of this effect, the sulfided sorbents were characterized by XRD and N 2 physisorption, and no correlation was found between the sulfidation rate and textural properties of formed sulfides. This result indicates that sulfur transport during sulfidation occurs by solid state rather than gas phase diffusion. Also XPS has shown that Cu 2 SÀZnS solid solution is formed during sulfidation of the Cu-doped solids. We thus suggest that diffusion enhancement in the presence of copper is brought about by sulfur vacancies created through charge compensation of Cu þ replacing Zn 2þ .

Catalytic Activation of a Solid Oxide in Electronic Contact With Gold Nanoparticles

“…We investigated the reactivity of ZnO towards a model organosulfur compound, thioacetamide. This choice was motivated by the use of oxides as solid-state adsorbents in desulfurization [37][38][39][40] and similar pollutant removal technologies. The reactivity of the oxide can be exploited for removing organosulfur compounds from hydrocarbon fuel streams by reactively adsorbing the organosulfur compound in the form of zinc sulfide (ZnS).…”

Feasibility Application of Cu-Contaminated Soil on the Removal of H₂S from Hot Coal Gas

“…This observation was consistent with the result obtained by Skrzypski et al in which their research shown that the fresh Cu/ZnO based-sorbent has a broad Cu XPS spectra and a narrow Cu peak was measured for the sulfide sample. 9) In addition to narrow and sharp feature, the binding energy of Cu shifts to lower energy (931.5 eV), indicating the appearance of Cu + in a sulfide environment. The Cu 2 S would be the main sulfide metal.…”

CO2 capture in humid gas using ZnO/activated carbon and ZnO reactivity with CO2

“…Based on the assumption described above, doping of other oxides into ZnO particles may work [43]. Copper and Zn form many types of composite oxides and composite carbonates [67][68][69].…”

“…This low reactivity of ZnO limits an application of ZnO to more acidic gases, e.g. SO x [41,42] and H 2 S [43,44]. Increasing the surface area enhances the reactivity of the oxide particles because of high surface to bulk ratio and increased steps and kinks on the surface [45,46].…”