水热法制备A型沸石粉体中的聚合生长

通过水热法制备A型沸石粉体实验和粉体表征,对水热条件下粉体晶粒的生长过程进行较深入的研究,提出了水热体系中A型沸石晶粒同时存在聚集生长和聚合生长。聚集生长是物粒从小尺寸粒子向大尺寸粒子输运的重结晶过程,而聚合生长则是小晶粒之间通过聚合作用形成粒度更大的晶粒的作用过程。两者的热力学驱动力都是由于晶粒平均粒度的增大降低了体系总的表面自由能。水热体系A型沸石晶粒的形成经历了前驱物溶解成核并形成纳米小粒子晶粒的聚合生长晶粒的聚集生长4个阶段,最后得到的晶粒以聚合生长为主,同时伴随着聚集生长的综合结果。

Aggregation Growth of Zeolite A Powders Synthesized by Hydrothermal Method

On basis of the hydrothermal preparation experiments of zeolite A powders and its testing and analysing token,the crystal growth process of zeolite A in hydrothermal conditon is investigated.It is put forward that there is not only coalescence growth but also aggriegation growth in crystal growth.The coalescence growth is the recrystallizing process of particles because the small particles transport to big particles.The aggregation growth is the process that the aggregation of small particles form big particles because the mutual action of the small particles.The thermaldynamics drive force of the two growth is that the total surface free energy is reduced because the accretion of the average granularity of the particles.In hydrothermal condition,the formation of the zeolite crystal come through such four phases as from the dissolutiom of the feedstocks to the growth of nucleus and the formation of nano particles to the aggregation growth of crystals to the coalescence growth crystals.The crystal that is prepared finally is the integrated results of aggregation and coalescence growth that aggregation growth give priority to coalescence.