Removal of Gaseous H2S by the Titanium Silicalite-1/H2O2 Wet Oxidation System

Abstract

A wet oxidation system of titanium silicalite-1 (TS-1)/hydrogen peroxide (H2O2) was proposed for gaseous hydrogen sulfide (H2S) removal in this study, and the effects of the TS-1 dosage, H2O2 concentration, H2S concentration, reaction temperature, gas flow, and reaction time on the removal rate of H2S (η) were investigated. Samples were characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance, and N2 adsorption–desorption. An experiment using isopropanol, benzoquinone, and butylated hydroxytoluene was carried out as well to verify the active substance in the TS-1/H2O2 system. The results show that η reached 86.3% when bubbling 160 ppm of H2S through a 500 mL solution (pH 4.21) containing TS-1 (0.5 g/L) and H2O2 (0.33 mol/L, 1.12 wt %) at 293 K and atmospheric pressure with a flow rate of 265 mL/min. Subsequently, the mechanism of the reaction was proposed. After the H2S diffuses onto the surface of TS-1, it is first oxidized by adsorbed H2O2 and eventually oxidized to H2SO4; this process is controlled by H2S diffusion. The final product of the process is sulfuric acid, which is pollution-free and can be recycled to achieve resource utilization. The removal of H2S by the TS-1/H2O2 system is a green, simple, low-cost, resource-saving, safe, and efficient method.