Low-temperature synthesis of Mg{sub x}Co{sub 1{minus}x}Co{sub 2}O{sub 4} spinel catalysts for N{sub 2}O decomposition
Low-temperature synthesis of spinels Mg{sub x}Co{sub 1{minus}x}Co{sub 2}O{sub 4} (x = 0.0--0.9) has been investigated with two important synthetic parameters and XRD/FTIR/DSC/BET/ICP/CHN methods. It is found that with an increase in hydrothermal treatment temperature, precursor compounds change from the hydrotalcite-like to brucite-like and then to cubic spinel phase when the initial metal concentration ratio [Mg{sup 2+}]:[Co{sup 2+}] {ge} 1, while from the turbostratic to hydrotalcite-like and then to cubic spinel phase when the [Mg{sup 2+}]:[Co{sup 2+}] < 1. The Mg{sub x}Co{sub 1{minus}x}Co{sub 2}O{sub 4} (x {le} 1/3) spinels were formed at temperatures as low as 50--100 C. In the postsynthesis thermal treatment, various thermal events have been observed, and in all cases the spinel phase can be prepared at temperatures below 300 C. On the basis of FTIR results, a topotactic mechanism for the formation of the spinel phase has been confirmed. Specific surface area as high as 210 m{sup 2}/g has been attained in 400 C calcined Mg{sub x}Co{sub 1{minus}x}Co{sub 2}O{sub 4} with x = 0.9. Causes for the formation of the spinel phase at low temperatures have been addressed. Excellent catalytic activity for N{sub 2}O decomposition (30.6 - 38.9 mmol (N{sub 2}O)/g{center_dot}h at GHSV = 21200 h {sup {minus}1} and 380--400 C; N{sub 2}O = 10 mol % balanced with He) has been observed and discussed for these Mg-Co spinels.
- Research Organization:
- National Univ. of Singapore (SG)
- OSTI ID:
- 20050858
- Journal Information:
- Chemistry of Materials, Journal Name: Chemistry of Materials Journal Issue: 3 Vol. 12; ISSN CMATEX; ISSN 0897-4756
- Country of Publication:
- United States
- Language:
- English
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