Mercury Adsorption by Sulfurized Fibrous Silicates

L. Daza1, S. Mendioroz1 and J. A. Pajares2
1 Instituto de Catálisis y Petroleoquímica C.S.I.C. Serrano 119, 28006 Madrid, Spain
2 Instituto del Carbón, C.S.I.C. La Corredoria, s/n. Oviedo, Spain

Abstract: To eliminate mercury vapor from gas streams, three major methods are used: condensation, absorption, and adsorption. This work deals with adsorption, using elemental sulfur as an active phase supported on sepiolite and palygorskite fibrous clays. Sulfur loads of 5–30% were deposited by catalytic oxidation of hydrogen sulfide at temperatures of <200°C, the clays acting first as a catalyst of the reaction and then as a carder of the obtained sulfur. The ability of the sulfurized clay adsorbents to retain mercury was studied at 45°C and 1 mm Hg pressure. The high values found, about 4 g Hg/g S supported on clays, compared with 1.69 g Hg/g S on activated carbon under the same conditions are related to a more appropriate pore size distribution, with more of the pore widths >6 nm for the sulfurized silicates. Also, the allotropic state of the deposited sulfur, where Sπ (octo-catena) is better than Sλ (octo-cycle), may also be a contributing factor.

Key Words: Activated carbon • Adsorption • Mercury • Palygorskite • Pore size distribution • Sepiolite • Sulfurized silicates

Clays and Clay Minerals; February 1991 v. 39; no. 1; p. 14-21; DOI: 10.1346/CCMN.1991.0390102
© 1991, The Clay Minerals Society
Clay Minerals Society (www.clays.org)