The Kinetics and Mechanism of Spontaneous Dispersion of Ionic Compounds Onto Surfaces of Supports

【摘要】 <正> The dispersion kinetics of ionic compounds on the surfaces of supports is studied by using atemperature-programmed X-ray diffractometer.It is observed that for a given ionic compound/support mix-ture,there exists a critical dispersion temperature T_c,at which the ionic compound starts to disperse ontothe surface of the support at an appreciable rate.The dispersion process has 2 steps:the ions first leave thesurface of the ionic compound for the external surface of the support,and then the ions diffuse to the wholesurface of the support.For the dispersion of ionic compounds with high melting points,the first step is rate-determining.Their critical dispersion temperatures and dispersion activation energies depend on the ioniccompounds themselves and increase with their melting points,but are independent of supports.For the dis-persion of ionic compounds with low melting points,the second step is rate-determining.Their critical dis-persion temperatures and dispersion activation energies depend on both the ionic compounds and the sup-ports.更多还原

【Abstract】 The dispersion kinetics of ionic compounds on the surfaces of supports is studied by using a temperature-programmed X-ray diffractometer.It is observed that for a given ionic compound/support mix- ture,there exists a critical dispersion temperature T_c,at which the ionic compound starts to disperse onto the surface of the support at an appreciable rate.The dispersion process has 2 steps:the ions first leave the surface of the ionic compound for the external surface of the support,and then the ions diffuse to the whole surface of the support.For the dispersion of ionic compounds with high melting points,the first step is rate- determining.Their critical dispersion temperatures and dispersion activation energies depend on the ionic compounds themselves and increase with their melting points,but are independent of supports.For the dis- persion of ionic compounds with low melting points,the second step is rate-determining.Their critical dis- persion temperatures and dispersion activation energies depend on both the ionic compounds and the sup- ports.更多还原