膨润土碱熔活化合成4A分子筛的研究

以天然膨润土为原料，采用高温碱熔水热法合成4A分子筛。探讨了活化温度、SiO2/Al2O3、Na2O/SiO2、H2O/Na2O等工艺条件对4A分子筛结构与性能的影响。结果表明，最佳的活化温度为600℃；物料经此温度活化后，调节组成为SiO2/Al2O3=1.5、Na2O/SiO2=3与H2O/Na2O=50，于90℃反应6小时可以得到质量较好的4A分子筛，其产品的晶形规整，晶粒均小于2μm，钙离子交换容量可达到314mg CaCO3/g。

Study on the Synthesis of 4A zeolite from alkali-activated Bentonite

Bentonite reacted with NaOH at a high temperature leading to a very reactive starting material for zeolite synthesis. Zeolite 4A was synthesized by hydrothermal method with natural bentonite as raw material. The effects of activation temperature, molar ratio of SiO_2/Al_2O_3, molar ratio of Na_2O/SiO_2, molar ratio of H_2O/Na_2O on the properties of the products were investigated by means of XRD, SEM and calcium ion exchange capacity. The results show that the best activation temperature was 600 ℃. After activation of the materials, the composition of the mixed compound was regulated as(molar ratio):SiO_2/Al_2O_3 =1.5, Na_2O/SiO_2=3 and H_2O/Na_2O=50, then crystallization was carried out at 90 ℃ for 6 h. Under the optimal conditions, zeolite 4A with a high degree of crystallinity, a small granularity of particles(most of the particle size of zeolite 4A was less than 2 μm) and high calcium ion exchange capacity(314 mg CaCO_3/g) was obtained.