Mechanism of activity enhancement of the Ni based hydrotalcite-derived materials in carbonyl sulfide removal

In this paper, a series of Ni based hydrotalcite-like compounds (HTLCs) were prepared by co-precipitation method. Carbonyl sulfide (COS) removal was investigated over the hydrotalcite-derived oxides (HTO). The properties of desulfurizer and its changes in the desulfurization process were systematically characterized by XRD, SEM, FTIR, CO2-TPD, XPS, XAFS and In-situ DRIFTS. The results showed that the activity series for removal of COS decrease in the following sequence: Ni3A1-HTO > Ni3Fe-HTO > Ni3Cr-HTO. In situ DRIFTS and quantum chemistry study implied that carbonate and sulfate was formed on the desulfurizer surface. Lewis basic sites and hydroxyl was determined to play a pivotal role for the COS removal. The enhanced activity after trivalent cations substitution is attributed to their high ability to provide electrons as evidenced by results of CO2-TPD, XPS and XAFS. This work is useful to explore feasible routes to improve the performance of desulfurization material for the feed gas purification. (C) 2017 Elsevier B.V. All rights reserved