Insight of intensified absorption and hydrolysis of COS in ternary system of TBEE and PEG200 and H2O

Abstract

To further improve carbonyl sulfide (COS) removal efficiency and develop green desulfurization process, a novel ternary desulfurization system with tert-butylaminoethoxyethanol (TBEE) as catalyst, polyethylene glycol (PEG, MW200) as promoter and H2O as reactant is constructed. Under atmospheric pressure and ambient temperature, the absorption performance of carbonyl sulfide can reach 95% with an optimal volume proportion of TBEE: PEG200: H2O at 3:3:4 (V/V/V). In this paper, the first-order hydrolysis reaction kinetic of the desulfurization system and COS was established in the range of 298–338 K. The FT-IR spectra and NMR results demonstrate that TBEE and PEG200 increase the physical solubility as gas phase transfer agents to enhance gas-liquid mass transfer substantially. The results of DFT calculation confirms that the presences of TBEE as a catalyst and H2O is introduced as an essential reactant. TBEE can activate H2O molecules and promote hydrolysis of COS. The hydrolysis of COS in this system is carried out by forming HCO2S- intermediate.