反应物的变化对吸附相反应技术制备NiO/SiO2的影响

以SiO2为载体,研究反应物种类和浓度对吸附相反应技术制备NiO粒子的影响。首先采用滴定法测定了各个反应物在载体表面的吸附过程,利用TEM、XRD分析,对比了不同反应物制备得到的NiO粒子的形貌。在确定了反应物的基础上,进一步设计了2种水量下制备实验,研究反应物浓度对粒子形貌的影响。XRD结果表明,1.0mL水量下NiO粒子的晶粒粒径随着反应物浓度增加先缓慢减少后增大。而随反应物浓度增加,5.0mL水量得到的粒子晶粒粒径则一直变大。2种吸附层中不同的反应速率使得相同条件下,高水量(5.0mL)得到的NiO粒子粒径要小于1.0mL水量下得到的粒子。物理吸附层中形成的粒子与载体结合力较弱,使得焙烧后5.0mL水量下得到的粒子在SiO2上分布不均匀。

Influence of Reactant on Preparation of NiO/SiO2 via Adsorption Phase Reaction Technique

Influence of reactant and its concentration was studied on preparation of NiO nanoparticles over SiO2 surface via adsorption phase reaction technique. Titration methods were used to measure the change in adsorption of the reagents on the support surface. NiO particles prepared by different reagents were characterized by TEM and XRD analysis. The XRD results indicate that the grain size of NiO prepared under 1.0 mL water changes little first,then increases with the increase in reactant concentration. Whereas the grain size of samples prepared under 5.0 mL water continues to increase with reactant concentration increasing. Reaction rate in two adsorption layer is so different that the grain size of NiO prepared under high water concentration(5.0 mL) is larger than those gained under 1.0 mL water. The binding of supports and particles formed in physical-adsorption layer is very weak,leading to non-uniform distribution of particles on SiO2 surface after calcination.