The deposition of elemental sulfur on porous adsorbents (commercial pre-sulfurised activated carbons and alumina, an HY zeolite and a selenised adsorbent) has been observed when the adsorbents are exposed to a gaseous stream containing hydrogen sulfide and oxygen. The sulfur deposition from H2S is more marked for the activated carbons and the alumina, it is substantially decreased when zeolite is used, and is practically insignificant for the selenium-based adsorbent. For the pre-sulfurised activated carbons, further sulfur deposition is initially beneficial in terms of increasing their mercury chemisorbing capacity but, subsequently, the structural properties are affected and this results in a drastic reduction in adsorption capacity. Further sulfur deposition on the pre-sulfurised alumina seems immediately to compromise its capacity to chemisorb mercury. The selenium-based adsorbent shows problems with detachment of the fine mercuric selenide powder from the matrix. Sulfur deposition on the initially unsulfurised zeolite improves its mercury adsorption capability. The initially sulfur-free zeolite could be a promising adsorbent for the treatment of this specific type of gas stream. In fact, after a moderate level of sulfur deposition from oxidation of hydrogen sulfide, it can simultaneously chemisorb the mercury vapours by reaction with the sulfur itself while, unlike the activated carbons and alumina, maintaining its required structural properties for a relatively long period.
Deposition of sulfur from H2S on porous adsorbents and effect on their mercury adsorption capacity
VITOLO, SANDRA;
1999-01-01
Abstract
The deposition of elemental sulfur on porous adsorbents (commercial pre-sulfurised activated carbons and alumina, an HY zeolite and a selenised adsorbent) has been observed when the adsorbents are exposed to a gaseous stream containing hydrogen sulfide and oxygen. The sulfur deposition from H2S is more marked for the activated carbons and the alumina, it is substantially decreased when zeolite is used, and is practically insignificant for the selenium-based adsorbent. For the pre-sulfurised activated carbons, further sulfur deposition is initially beneficial in terms of increasing their mercury chemisorbing capacity but, subsequently, the structural properties are affected and this results in a drastic reduction in adsorption capacity. Further sulfur deposition on the pre-sulfurised alumina seems immediately to compromise its capacity to chemisorb mercury. The selenium-based adsorbent shows problems with detachment of the fine mercuric selenide powder from the matrix. Sulfur deposition on the initially unsulfurised zeolite improves its mercury adsorption capability. The initially sulfur-free zeolite could be a promising adsorbent for the treatment of this specific type of gas stream. In fact, after a moderate level of sulfur deposition from oxidation of hydrogen sulfide, it can simultaneously chemisorb the mercury vapours by reaction with the sulfur itself while, unlike the activated carbons and alumina, maintaining its required structural properties for a relatively long period.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
