Critical Role of Water on the Surface of ZnO in H2S Removal at Room Temperature

H2S removal was carried out in the absence and presence of water over a ZnO sorbent at room temperature. It was clear that water remarkably promotes the removal of H2S and significantly enhances the activity of ZnO compared with the dry feed. We performed an experimental and computational study to illustrate the specific role of water in this process. In situ diffuse reflectance infrared Fourier transform (DRIFT) and X-ray photoelectron spectroscopy experiments showed that water adsorbs on the surface of ZnO in the forms of hydroxyl group and chemisorbed water molecule. Density functional theory (DFT) calculations indicated that the hydroxyl group on the surface of ZnO changes the reaction pathway of ZnO and H2S and ultimately reduces the reaction activation energy significantly, whereas the chemisorbed water molecule has no substantial influence on this reaction pathway. Thermogravimetry and in situ DRIFT experiments further confirmed the positive role of the hydroxyl group by comparing the initial conve...