Low-temperature synthesis of MgxCo1-xCo2O4 spinel catalysts for N2O decomposition

Low-temperature synthesis of spinels MgxCo1-xCo2O4 (x = 0.0-0.9) has been i nvestigated with two important synthetic parameters and XRD/FTIR/DSC/BET/IC P/CHN methods. It; is found that with an increase in hydrothermal treatment temperature, precursor compounds change from the hydrotalcite-like to bruc ite-like and then to cubic spinel phase when the initial metal concentratio n ratio [Mg2+]:[Co2+] greater than or equal to 1, while from the turbostrat ic to hydrotalcite-like and then to cubic spinel phase when the [Mg2+]:[Co2 +] < 1. The MgxCo1-xCo2O4 (x less than or equal to 1/3) spinels were formed at temperatures as low as 50-100 degrees C. In the postsynthesis thermal t reatment, various thermal events have been observed, and in all cases the s pinel phase can be prepared at temperatures below 300 degrees C. On the bas is of FTIR results, a topotactic mechanism for the formation of the spinel phase has been confirmed. Specific surface area as high as 210 m(2)/g has b een attained in 400 degrees C calcined MgxCo1-xCo2O4 with x = 0.9. Causes f or the formation of the spinel phase at low temperatures have been addresse d. Excellent catalytic activity for N2O decomposition (30.6-38.9 mmol (N2O) /g.h at GHSV = 21200 h(-1) and 380-400 degrees C; N2O = 10 mol % balanced w ith He) has been observed and discussed for these Mg-Co spinels.