Existent state of ZrO 2 in fused iron catalyst and its influence on the reactivity of the catalyst

Abstract

XRD, LRS, thermogravimetric technique, BET surface area determination and catalytic activity measurements have been used to investigate the existent state of ZrO 2 in the fused iron catalyst with and without Y 2O 3 and the influence of them on the reactivity of fused iron catalyst for ammonia synthesis. The results of XRD and LRS show that zirconia exists in the form of yttria-stabilized cubic ZrO 2 in the fused iron catalysts with Y 2O 3 We also found that for the Y 2O 3-free fused iron catalysts, cubic phase zirconia can also be stabilized by incorporating Fe 2+ or Fe 3+ cations into its lattice, and Fe 2+-stabilized zirconia is more stable than Fe 3+-stabilized zirconia. The results of a reduction experiment indicate that Y 2O 3 has a promoting effect on the reduction of ZrO 2-promoted fused iron catalyst. The catalyst containing Y 2O 3 and ZrO 2 exhibits a higher activity than a current industrial catalyst. The role of zirconia and yttria was also discussed in this work.