Adsorption/oxidation of ethyl mercaptan on Fe-N-modified active carbon catalyst

Abstract

Ethyl mercaptans which commonly exist in natural gas have to be removed to a low level due to their toxic, odorous and corrosive properties. Herein, a novel Fe-N-modified active carbon catalyst was prepared for the ethyl mercaptans removal. The Fe3O4 phase provides main active sites for catalytic oxidation of the ethyl mercaptans. Introduction of nitrogen groups increases content and dispersion of the active Fe3O4 sites, which exposes more active sites accessible to the ethyl mercaptans. Besides, the formed nitrogen groups, including pyridinic-N, pyrrolic-N also contribute to adsorption and activation of the sulfur compounds. Therefore, sulfur capacity of the novel catalyst (238.3 mg/g) is more than three times that of the iron modified active carbon (70.1 mg/g) and nearly four times that of the pure active carbon (62.2 mg/g). The ethyl mercaptans are oxidized into diethyl disulfides and metal sulfonates over the novel catalyst. All the oxidation products as well as the ethyl mercaptans are adsorbed by the catalyst. The sulfur capacity of the exhausted catalyst can be restored to nearly eighty percent of the fresh one after a simple thermal treatment.