Fe(Ⅲ)Y型沸石的制备及表征

Preparation and Characteristic of Fe(Ⅲ)Y Zeolites

采用化学分析 ,低温氮吸附 ,穆斯堡尔谱和程序升温还原 (TPR) ,X光粉末衍射 (XRD)等方法研究了不同方法制备的Fe(Ⅲ )Y沸石的结构特征 ,铁的状态和还原性 .发现在弱酸和弱碱性溶液中制备的Fe(Ⅲ )Y沸石具有更稳定的骨架结构 ,脱铝较少 ,Fe(Ⅲ )以四面体状态存在 .焙烧后 ,Fe(Ⅲ )的状态由四面体形式转变为八面体 ,并且形成 10nm的超细粒子 ,在穆斯堡尔谱上观察到四极分裂的双线谱 .但在强酸溶液中制备的Fe(Ⅲ )Y ,除了超细的α Fe2 O3 外 ,还观察到较大颗粒的α Fe2 O3 和α Fe2 O3 ·Y .它们对应不同的局域环境 ,在穆斯堡尔谱上分别对应于二组磁分裂的六线谱和一组四极分裂的双线谱 .

The characteristic of structure, the state of Fe(Ⅲ) and the reductivity of Fe(Ⅲ)Y zeolites prepared with various methods were investigated by chemical analysis, adsorption of N 2 at the temperature of liquid Nitrogen, Mǒssbauer spectra TPR and XRD. It is found that the Fe(Ⅲ)Y prepared in weak acidic or weak basic solution has more stable framework structure and less dealumination and the state of Fe(Ⅲ) exists in the form of tetrahedron. After calcination, the state of Fe(Ⅲ) is transferred from tetrahedron to octahedra and the ultrafine particles of Fe(Ⅲ) of 10 nm are formed, it's Mǒssbauer spectrum only consists of a quadrupole doublet. But for Fe(Ⅲ) Y prepared from the strong acid solution, apart from the ultrafine particle of α Fe 2O 3, the larger particles of α Fe 2O 3 and α Fe 2O 3 Y were also observed. They are corresponded to two groups of six lines hyperfine structure and one quadrupole doublet, respectively.