New sulfur adsorbents derived from layered double hydroxides I: Synthesis and COS adsorption

Mixed oxides, prepared via the thermal decomposition of layered double hydroxides (LDHs), were screened gravimetrically for their ability to adsorb carbonyl sulfide (COS). Based on promising results obtained for Ni/Mg/Al, Ni/Mg/Fe and Co/Mg/Al mixed oxides, a study was undertaken to optimize the com...

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Bibliographic Details
Published in:Applied catalysis. B, Environmental Environmental, 2008-08, Vol.82 (3-4), p.190-198
Main Authors: SPARKS, Dennis E, MORGAN, Tonya, PATTERSON, Patricia M, ADAM TACKETT, S, MORRIS, Erin, CROCKER, Mark
Format: Article
Language:English
Subjects:
Adsorption
Atmosphere
carbonyl compounds
Catalysis
Chemistry
Exact sciences and technology
Feeds
General and physical chemistry
hydroxides
Magnesium
Metals
Q1
regeneration
Sulfides
Sulfur
Surface physical chemistry
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
thermal decomposition
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Summary:Mixed oxides, prepared via the thermal decomposition of layered double hydroxides (LDHs), were screened gravimetrically for their ability to adsorb carbonyl sulfide (COS). Based on promising results obtained for Ni/Mg/Al, Ni/Mg/Fe and Co/Mg/Al mixed oxides, a study was undertaken to optimize the composition of these materials for COS adsorption. To investigate the effect of the M(II):M(III) ratio, LDHs of the type [M sub(z)Mg sub(y)Al sub(x)(OH) sub(2)](CO sub(3)) sub(x/2).0.5H sub(2)O (where M = Ni or Co, and x + y + z = 1) were prepared at values of x corresponding to 0.33 and 0.20. Simultaneously, the elemental ratio of transition metal to magnesium (z/y) was varied. Mixed oxides obtained from the resulting LDHs were tested in fixed bed mode with a feed of 100 ppm COS in N sub(2) to determine breakthrough capacity. In general Ni/Mg/Al mixed oxides showed the best performance, a composition with Ni/Mg/Al = 0.32/0.48/0.20 showing the best adsorption capacity. Treatment of the spent adsorbent under an atmosphere of 5% H sub(2) in N sub(2) at 450 degree C was found to provide an effective means of restoring the adsorption capacity over two cycles of adsorption and regeneration, although after three such cycles, adsorption capacity decreased.
ISSN:0926-3373
1873-3883
DOI:10.1016/j.apcatb.2008.01.012