正电子素探测多孔材料内表面特性

本文讨论了以正电子素为探针探测不同相结构的氧化铝和HY分子筛等多孔材料内表面的一些物理和化学性质.发现在α、θ混合桐的氧化铝中存在着孔径为不到1纳米的小孔和几个纳米的大孔,随着温度升高,小孔向着大孔方向扩胀.也发现在非活性的氧化铝中表面正电子素强度与孔的比表面积存在着线性关系,在活性氧化铝中却有明显的偏离.还发现正电子素在HY分子筛内表面和笼内与质子酸发生了氧化还原反应,并求出了反应速率常数。

Study of the Inner Surface Properties of Porous Material Using Positronium as a Probe

This paper discusses the results of positron lifetime measurement in alumina powder with different phase structures and in HY type zeolite. The inner surface properties of these materials are also investigated. We discovered that the small and large pores exist in α and θ mixed phase alumina. For surface with inert states, we found the intensity of positronium on the surface of alumina is linear with the specific surface area. However, for surface with active states, the intensity of positronium is obviously reduced. The results of positron annihilation parameters for HY type zeolite show the occurrence of the redox reaction of positronium with H~+ acid in the inner surface of HY type zeolite and in the cage. The reaction rate constant in inner surface is K = 9.67× 10~7(mol/kg)~(-1)s~(-1) the reaction rate constant in cage is K = 2.36×10~7(mol/kg)~(-1)s~(-1).