Adsorptive Removal of t-Butanethiol Using Metal Ion-exchange Y Type Zeolite under Ambient Conditions

Adsorptive removal of t-butanethiol (TBT), an odorant additive, from city gas was carried out using metal ion-exchange Y type zeolites at ambient temperature and pressure. The adsorption capacity of TBT on Na-Y under the wet gas condition was extremely low, although that under the dry gas condition was certainly higher. The adsorption capacity of TBT on silver ion-exchange Y type zeolites (Ag(Na)–Y) increased with higher silver ion-exchange ratio in Ag(Na)–Y under wet gas condition. In contrast, the adsorption capacity of TBT on Ag(Na)–Y under the dry gas condition decreased with higher silver ion-exchange ratio in Ag(Na)–Y. Formation of silver sulfide clusters in Ag(Na)–Y causes the decrease in sulfur adsorption capacity of it under the dry gas condition. The adsorption capacity of TBT on copper ion-exchange Y type zeolites (Cu(Na)–Y) increased with higher copper ion-exchange ratio in Cu(Na)–Y under the wet gas condition. In the case of Cu(Na)–Y, the decrease of TBT adsorption capacity under the dry gas condition did not occur with higher copper ion-exchange ratio in Cu(Na)–Y. The both spent samples of Ag(Na)–Y and Cu(Na)–Y were regenerated by heat treatment in air. The decrease in adsorption capacity of TBT on Cu(Na)–Y was slightly lower than that on Ag(Na)–Y.