Raney-Cu催化剂的烧结行为

A STUDY ON THE SINTERING BEHAVIOUR OF RANEY-COPPER CATALYST

用SSA、PSD、XRD及SEM等实验手段研究了自制Raney-Cu催化剂在不同温度及不同气氛中的烧结行为。发现催化剂表面的烧结分为前后两个不同阶段,各对应于表面上不同孔径的收缩及封堵,催化剂表面的烧结程度与各种气体分子的吸附强度相联系。建立了表面积收缩的动力学方程,对烧结机理进行了探讨。文章指出,烧结行为包括表面及体相两方面的变化。积炭的产生掩盖了铜催化剂表面积的收缩,但加速了体相结晶度的提高。应用量子力学方法计算的烧结起始温度与实验结果吻合较好。

Methods of SSA (specific surface area), PSD (pore size distribution) XRD and SEM were employed to investigate the sintering of Raney-copper catalyst under various atmospheres at 300鈩?600鈩? It is found that sintering takes place at temperatures much lower than the melting point of solid copper;and that the decrease of surface area can be divided into two stages, each of which is correlated to the shrinking and closing of different groups of pores in the original sample. The extent of sintering under various atmospheres varies inversely as the adsroption strength of the gaseous atoms on the catalyst. A kinetic model of surface shrinkage has been established. The mechanism of sintering is discussed and it is thought that sintering happens both in the bulk and on the surface, with the latter more pronounced because of the action of two driving forces.Deposited carbon can accelerate the crystallization of the bulk phase.Quantum mechanical calculations were performed and the predicted starting temperature of sintering of Raney-Cu conforms well to the experimental result.