Mercury chemisorption by sulfur adsorbed in porous materials

Abstract

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 ~vith a micropore volume approximately half filled with sulfur.

Catalytic Oxidation of Hydrogen Sulfide. Influence of Pore Structure and Chemical Composition of Various Porous Substances

“…(1) The appearance of a maximum activity is a function of the amount of sorbed sulfur by a material. As we demonstrated in a previous paper (Steijns et al, 1976a), this maximum corresponds to a maximum in the specific sulfur surface area. The activity maximum is often not observed because of a high intrinsic catalytic activity of the carrier.…”

Flue Gas Hg0 Removal by FeCl3-Impregnated LTA and MFI Zeolites: Influences of Topology and Cation Sites

“…Hence, Fe/ZSM-5 owns a certain pore volume, which provides the adsorption sites required for physical adsorption. Also, the pore diameter is about 4.3 Å, which is slightly larger than the diameter of Hg 0 ; consequently, Hg 0 can be adsorbed in the microporous channel of ZSM-5. , In addition, two obvious desorption peaks were observed in Fe/5A samples at 302 and 449 °C but not in ZSM-5 and silicalite-I zeolite samples, and these peaks might correspond to HgO. On the basis of the analysis of XPS and XRD, we may draw a conclusion that the combination of lattice oxygen and chemisorbed oxygen in Fe/5A contributes to the oxidation of Hg 0 to HgO. , Comparing the peak area of the three desorption peaks on the Fe/5A sample, the desorption peak of HgCl 2 only accounted for a small proportion, indicating that the adsorption of HgCl 2 on the Fe/5A sample surface is less, and the main mercury adsorption form was HgO.…”

“…Also, the pore diameter is about 4.3 Å, which is slightly larger than the diameter of Hg 0 ; consequently, Hg 0 can be adsorbed in the microporous channel of ZSM-5. 24,55 In addition, two obvious desorption peaks were observed in Fe/5A samples at 302 and 449 °C but not in ZSM-5 and silicalite-I zeolite samples, and these peaks might correspond to HgO. On the basis of the analysis of XPS and XRD, we may draw a conclusion that the combination of lattice oxygen and chemisorbed oxygen in Fe/5A contributes to the oxidation of Hg 0 to HgO.…”

Mercury Adsorption by Sulfurized Fibrous Silicates

“…The capacity for adsorbing mercury was studied in the static system described by Steijns et al (1976), as modified by Daza (1986). The system consisted of a mercury-containing device mounted on top of an ordinary dessicator attached to a vacuum pump, which ensured a total mercury pressure inside the dessicator of < 1 mm Hg.…”