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本文用程序升温高温X射线衍射仪研究了若干盐类在不同载体表面上自发分散的动力学规律。结果表明:对一定的盐类和载体混合物存在一个特定的温度,在等于或高于此温度下烘烤样品明显地观察到盐类在载体表面分散,此温度称为临界分散温度。它可以作为衡量分散过程难易的量度。盐类分散过程可分为两步:第一步是盐类离开其晶相转移到载体外表面;第二步是盐类沿载体表面扩散而分散到载体整个内表面。对于较高熔点(一般大子400℃)盐类来说,临界分散温度和分散活化能的大小顺序常常与其熔点的大小顺序一致,对不同载体其临界分散温度和分散活化能差别很小,并且临界分散温度与盐类开始明显热无序的温度一致,说明分散速度控制步骤是第一步;对于较低熔点盐类来说,临界分散温度和分散活化能的大小顺序没有明显的对应关系,受载体种类影响很大,说明第二步是分散速度控制步骤。
In this paper, temperature-programmed high temperature X-ray diffractometer was used to study the kinetics of spontaneous dispersion of several salts on different support surfaces. The results show that for certain salts and carrier mixtures there is a specific temperature at which the salt is clearly observed to be dispersed on the carrier surface at or above which the temperature is referred to as the critical dispersion temperature. It can be used as a measure of the difficulty of decentralization. Salt dispersion process can be divided into two steps: the first step is to leave the salt phase transfer to the outer surface of the carrier; the second step is to spread along the surface of the salt dispersion and dispersed throughout the inner surface of the carrier. For the higher melting point (usually 400 ℃) salt, the order of the critical dispersion temperature and dispersion activation energy is often in accordance with the order of their melting point, the difference between the critical dispersion temperature and the dispersion activation energy is very small for different carriers, and The critical dispersion temperature is consistent with the temperature at which the salts begin to show significant thermal disordering, indicating that the dispersion rate control step is the first step; there is no clear correspondence between the critical dispersion temperature and the dispersion activation energy order for the lower melting salts, Affected by the type of carrier is very large, indicating that the second step is the dispersion speed control steps.