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.
|Number of pages||9|
|Journal||Applied Catalysis B: Environmental|
|State||Published - Aug 8 2008|
Bibliographical noteFunding 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.
- Carbonyl sulfide
- Layered double hydroxide
- Methyl mercaptan
ASJC Scopus subject areas
- Environmental Science (all)
- Process Chemistry and Technology