Mercury chemisorption by sulfur adsorbed in porous materials

The sorption of mercury vapor by adsorbed sulfur in the zeolites CaA (= 5A) and NaX (=13X) and two types of active carbon has been measured at a temperature of 50°C. With increasing degree of micropore filling by sulfur the fraction of sulfur accessible to mercury atoms decreased for CaA and NaX. The sulfur chemisorbed on carbon (only less than 0.05 g sulfur per g) is not very active for mercury chemisorption. The mercury uptake shows a sharp maximum as a function of the amount of sorbed sulfur in the case of CaA, NaX and activated sugar charcoal. The oxidation rate of H2S with oxygen on NaX and activated sugar charcoal correlates with the capacity for mercury chemisorption, both as a function of the amount of sorbed sulfur. From the amount of sorbed mercury an estimate of the specific sulfur surface area may be given. When sulfur impregnated CaA, NaX or activated sugar charcoal are used as adsorbents for mercury traces out of gas streams, the mercury sorption capacity may be maximized by using materials with a micropore volume approximately half filled with sulfur.