期刊
JOURNAL OF HAZARDOUS MATERIALS
卷 342, 期 -, 页码 749-757出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jhazmat.2017.09.014
关键词
Layered double hydroxides; Rare earth catalysts; H2S selective oxidation; Water effect; Catalytic mechanism
资金
- National Natural Science Foundation [21507148, 21577158, 21337003]
A series of well-mixed Ce-containing MgAlCe rare earth catalysts derived from layered double hydroxides were synthesized and tested for H2S selective catalytic oxidation. Particularly, no chemisorption O-vacancies but intrinsic defect sites were present on catalyst surface. Significantly, the catalysts exhibited excellent catalytic activity, reasonable durability, and outstanding sulfur selectivity (100%) at relatively low temperatures. Furthermore, the catalyst followed a step-wise mechanism, and the catalyst deactivation was due mainly to the slower oxidation rate of Ce3+ to Ce4+ by O-2 as compared to the reduction rate of Ce4+ to Ce3+ by H2S. Particularly, the added water, a Lewis base, can compete with inefficient S-8 catalyst for the occupation of Lewis acid sites and active sites. Meanwhile, it can change the characteristics of catalyst surface, resulting in sulfur existing form transforming from inefficient S-8 catalyst to inactive S3. Thus, lead to a decrease of deposited inefficient S-8 catalyst content. Consequently, decrease the catalytic activity. (C) 2017 Elsevier B.V. All rights reserved.
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