Adsorption/desorption of low concentration of carbonyl sulfide by impregnated activated carbon under micro-oxygen conditions

Activated carbon modified with different impregnants has been studied for COS removal efficiency under micro-oxygen conditions. Activated carbon modified with Cu(NO3)(2)-CoPcS-KOH (denoted as Cu-Co-KW) is found to have markedly enhanced adsorption purification ability. In the adsorption purification process, the reaction temperature, oxygen concentration, and relative humidity of the gas are determined to be three crucial factors. A breakthrough of 43.34 mg COS/g adsorbent at 60 degrees C and 30% relative humidity with 1.0% oxygen is shown in Cu-Co-KW for removing COS. The structures of the activated carbon samples are characterized using nitrogen adsorption, and their surface chemical structures are analyzed with X-ray photoelectron spectroscopy (XPS). Modification of Cu(NO3)(2)-CoPcS-KOH appears to improve the COS removal capacity significantly, during which, SO42- is presumably formed, strongly adsorbed, and present in the micropores ranging from 0.7 to 1.5 nm. TPD is used to identify the products containing sulfur species on the carbon surface, where SO2 and COS are detected in the effluent gas generated from exhausted Cu-Co-KW (denoted Cu-Co-KWE). According to the current study results, the activated carbon impregnated with Cu(NO3)(2)-CoPcS-KOH promises a good candidate for COS adsorbent, with the purified gas meeting requirements for desirable chemical feed stocks. (C) 2012 Elsevier B.V. All rights reserved.