摘要
用草酸高铁铵浸渍NaY沸石,并在高温下焙烧,得到α-Fe_2O_3/NaY沸石体系。经XRD相定量外推法测定,α-Fe_2O_3在NaY沸石上的最大分散量为0.060gα-Fe_2O_3/gNaY,仅占α-Fe_2O_3在沸石表面密置单层量的5.5%。首次尝试用正电子寿命谱方法测定α-Fe_2O_3在沸石表面的最大分散量,所得结果与XRD方法完全吻合。由程序升温还原方法发现沸石上α-Fe_2O_3的还原分两步进行,α-Fe_2O_3先还原成Fe_3O_4,然后再还原成金属。α-Fe_2O_3分散相与沸石之间的强相互作用,使这两个还原反应受到阻抑。
The α-Fe_2O_3/NaY zeolite samples were prepared by impregnating NaY zeolite with ammonium ferrioxalate solution and calcining at high temperature. The maximum dispersion amount of α-Fe_2O_3 on NaY zeolite measured with XRD quantitative phase analysis is 0.060 gα-Fe_2O_3/gNaY, which is only 5.5% of the monolayer capacity of α-Fe_2O_3 on NaY according to a close-packed monolayer model. For the first time positron lifetime spectroscopy has been used to detect the dispersion amount of oxide on zeolite.The maximum dispersion amount of α-Fe_2O_3 obtained is fully consistent with that obtained from XRD phase analysis. TPR spectra of the samples show that the reduction of α-Fe_2O_3 on the zeolite consists of two steps, α-Fe_2O_3 is first reduced to Fe_3O_4 at low temperature and then to the metal at higher temperature. Both reduction reactions are inhibited by the strong interaction of the dispersed α-Fe_2O_3 phase with the zeolite.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
1991年第1期16-21,共6页
Acta Physico-Chimica Sinica
基金
国家自然科学基金
关键词
氧化铁体系
NAY
沸石
催化剂
分散
伪-Fe_2O_3, NaY zeolite, XRD, Positron lifetime spectroscopy
