Removal of hydrogen sulfide by metal-free amine-functionalized mesoporous carbon at room temperature: Effect of amines

The introduction of nitrogen can effectively improve the alkalinity of carbon materials, introduce catalytic sites and active oxygen radicals, thus enhancing the desulfurization ability. However, the study on the effect of amine species and loading amount on the desulfurization properties is very limited. In this study, mesoporous carbon materials with large specific surface area and pore volume were prepared. Different amines were selected as impregnating agents to investigate the performance of amine-functionalized carbon catalysts for hydrogen sul-fide (H2S) removal under various operating conditions. The synthesized carbon material has a large specific surface area of 989 m2/g, with an average pore diameter of 12.94 nm. The well-developed pores could not only provide the space for the dispersion of amine, but also facilitate the diffusion of H2S and the storage of sulfur products. Amine increase the alkalinity of carbon material and the reactivity of reaction sites located on the carbon skeleton. The desirable catalytic performance of catalysts impregnated by amines should be the compromise among spatial structure of the amine, the surface chemistry and porosity of catalysts. Among them, the polyethylene polyamine impregnated carbon catalyst with a high ratio of secondary and tertiary amine (80.54 %) showed the best catalytic performance of 1.58 g H2S/g-catalyst at 30 degrees C due to due to suitable steric hindrance and higher stability in the H2S adsorption-desorption cycle. This work further refines the previously proposed reaction mechanism and provides a possibility for the application of carbon-based catalysts with directional introduction of nitrogen elements by impregnation method in the removal of H2S.