Abstract
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 [MzMgyAlx(OH)2](CO3)x/2·0.5H2O (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 N2 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% H2 in N2 at 450 °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.
Original language | English |
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Pages (from-to) | 190-198 |
Number of pages | 9 |
Journal | Applied Catalysis B: Environmental |
Volume | 82 |
Issue number | 3-4 |
DOIs | |
State | Published - Aug 8 2008 |
Bibliographical note
Funding Information:The authors wish to thank Gerald Thomas for performing the X-ray diffraction measurements and Dr. Timothy C. Golden of Air Products and Chemicals, Inc. for providing commercial adsorbent samples. This research work was supported in part by a grant from the Kentucky Science and Engineering Foundation as per Grant Agreement #KSEF-148-502-05-134 with the Kentucky Science and Technology Corporation.
Keywords
- Adsorption
- Carbonyl sulfide
- Hydrotalcite
- Layered double hydroxide
- Methyl mercaptan
ASJC Scopus subject areas
- Catalysis
- General Environmental Science
- Process Chemistry and Technology