Metal Organic Frameworks for Selective Adsorption of t-Butyl Mercaptan from Natural Gas

Abstract

Pipeline natural gas is typically “odorized” with ∼10 ppm of sulfur-containing components, such as mercaptans, for ease of detection. Such odorants can be removed before being burned in electricity generation gas turbines to prevent or limit turbine corrosion and increase turbine lifetime. Selective adsorption of these odorants onto solid materials is an attractive approach to address this problem because of the ability to remove these trace levels of sulfur and to be operated at low temperatures, meaning that it is less energy-intensive than other traditional sulfur removal methods. Adsorbent material selection is important for this approach, and a material with high sulfur capacity, selectivity, and regenerability is desired for a practical implementation of such an adsorption system. In this study, several adsorbent materials are gravimetrically screened for t-butyl mercaptan (TBM) adsorption capacity and the best candidates, Cu-BTC, MIL-53(Al), and UiO-66(Zr), are compared to a benchmark material, zeolite NaY. These selected materials are evaluated with regard to their cyclic regenerability/stability and selectivity toward TBM over methane and other impurities. From the results of this study, UiO-66(Zr) emerges as a promising candidate material for this application.