For example, for the preparation of the 10 wt%
Fe/ZrO2 catalyst, ZrO2 (4.5 g) was first added into an aqueous solution
of Fe(NO3)3 (0.2 mol dm−3, 45 mL). The suspension was then
stirred for 8 h, followed by evaporation at 353K to dryness. The
obtained powdery catalyst was further dried at 393K for 12 h and
calcined in air at 773K for 5 h. The alkali metal ion-modified supported
Fe catalysts were prepared by a co-impregnation method
using a mixed aqueous solution containing certain amount of an
alkali metal salt (LiNO3, NaNO3, KNO3, RbCl or CsCl) and Fe(NO3)3
with a similar procedure.