(146f) Removal of Tetrahydrothiophene by an Adsorption Method

Tetrahydrothiophene (THT) is one of widely-used odorants in city gas mainly composed of natural gas. Recently, fuel cells have attracted much interest especially as an environmental-friendly power source in which dihydrogen and dioxygen converted into water while producing heat and electricity. There are several types of fuel cell having different operating temperatures and fuel sources. One of strategies for fuel cell applications is to utilize natural gas in city gas as a hydrogen source. To do this, a couple of processes are in need. Generally, following units are connected in series prior to the polymer electrolyte membrane fuel cell (PEMFC); (1) a unit for steam-reforming reaction, (2) a unit for water-gas shift reaction, (3) a unit for removal of residual CO. Sulfur compounds present in city gas can cause severe deactivation in catalysts for above reactions even with very low concentrations. Therefore, complete removal of sulfur compounds is in order. Two different methods have been generally studied. One is the high-temperature catalytic desulfurization with dihydrogen over supported metal sulfide catalysts. The other is the low-temperature adsorption. Commercial bulk petroleum industry generally utilizes the former process where organic sulfur compounds are transformed into elemental sulfur. Although this unit is proven technology, it needs high temperature to sustain hydrogenation reaction. Usually, adsorption is regarded as a more effective method for deep desulfurization than is HDS. Until now, most adsorptive deep desulfurization studies have been conducted to remove organic sulfur compounds containing benzene derivatives in the liquid phase. To utilize city gas as a hydrogen source, studies on adsorptive removal of simple organic sulfur compounds in the gas phase should be carried out. In this report, THT was selected as a model compound and its adsorptive removal was performed over various materials. Characteristics of adsorption and desorption is correlated with physical and chemical properties of adsorbents via some characterization techniques.