Sulfur impregnation on activated carbon fibers through H2S oxidation for vapor phase mercury removal

Sulfur was impregnated onto activated carbon fibers (ACFs) through H2S oxidation catalyzed by the sorbent surface in a fixed-bed reactor. By changing the temperature and duration of the sulfur impregnation process, ACFs with different sulfur contents were developed. Characterization of ACFs before and after sulfur impregnation was conducted by surface area analysis, energy dispersive X-ray analysis, thermogravimetric analysis, X-ray photoelectron spectroscopy, and temperature programmed desorption. Vapor phase mercury adsorption experiments were carried out in a fixed-bed reactor. Sulfur was impregnated mainly as elemental sulfur and the amount of sulfur deposited on the ACF increased with an increase in impregnation temperature. Higher temperature leads to more uniform sulfur distribution inside the sorbent pores. The impregnation process can be explained by a combination of pore filling and monolayer adsorption, with the former mechanism predominating at low temperatures. In the absence of sulfur, the mercury adsorption capacity can be correlated with surface area and pore volume.