铁基高温变换催化剂制备的穆斯堡尔谱研究──Ⅱ．沉淀pH值对铁氧化物晶型的影响

STUDY ON THE PREPARATION OF Fe-BASED HICH TEMPERATURE SHIFT CATALYST BY MOSSBAUER SPECTROSCOPY Ⅱ.Influence of pH Value on the CrystallineType of Iron Oxide

铁基高温变换催化剂制备的穆斯堡尔谱研究──Ⅱ．沉淀ｐＨ值对铁氧化物晶型的影响马红钦，张继炎，张鎏，张宝峰（天津大学化工系，天津３０００７２）（天津大学应用物理系，天津３０００７２）关键词铁氧化物，制备，晶型，穆斯堡尔谱，混合沉淀剂，ｐＨ值我们研制的Ｂ...

he formation mechanism of iron oxides with different crystalline types from the precursors precipitated at different pH values was studied by Mossbauer spectroscopy and XRD. FeO (OH) and/or FeCO3 were precipitated at PH 6. 5 and 7. 5 when NH4OH-NH4HCO3 was used as the mixed precipitant, and the only product α-Fe2O3 was obtained after drying and calcination.While at pH 8. 5, Fe (OH)x(CO3)1-x/s was formed, and it was converted partially into Fe3O4·2H2O and FeO(OH) after aging in air. The former turned into γ-Fe2O3 and the latter into α-Fe2O3 after drying and calcination. The γ-Fe2O3/α-Fe2O3 ratio increased with the increase of pH value, and the only product γ-Fe2O3 was obtained at pH 9. 5.