加入有机溶剂合成超微A型沸石

Synthesis of ultramicro A zeolites using organic solvents

超微A型沸石分子筛是目前重要的环保吸附、离子交换及催化材料。采用水热合成法,利用廉价的工业原料水玻璃作硅源,合成了超微A型沸石分子筛。在分子筛晶化步骤前,加入一定量有机溶剂四氢呋喃、乙醇和丙酮等,促进分子筛的成核及晶体的生长,使得分子筛的晶化时间缩短,晶粒度减小。对合成产物用XRD、SEM、IR和激光粒度仪等进行了物相、形貌、结构及粒度分析,吸附量采用水中铵氮法测定。结果表明,当合成原料配比取n(Na2O)∶n(Al2O3)∶n(SiO2)∶n(H2O)=3∶1∶2∶185、晶化温度85℃,晶化时间8 h、加入四氢呋喃与Al2O3物质的量比为0.75∶1时,沸石结晶粒度由普通沸石的2μm以上减小为350 nm以下;吸附效率较普通沸石大大提高。

Ultramicro A zeolite is an important environmental protection （adsorption）, ion exchange and catalytic material. Ultramicro A zeolites were synthesized by hydrothermal method using inexpensive commercial sodium silicate as the silicon source. Organic solvent such as tetrahydrofuran（ THF）, ethanol and acetone was added into the precursor solution before the crystallization step to promote formation of nucleus and growth of crystals, so as to shorten crystallization time and reduce the crystal size. The phase, morphology, structure and granule size were characterized by XRD, SEM, IR and laser granularity measurement. Crystal particle size of the zeolite was reduced from over 2 μm for conventional zeolite to less than 350 nm with greatly enhanced adsorption efficiency under the following condition： n（ Na2O） ： n（ Al2O3 ） ： n（ SiO2 ） ： n（ H2O） = 3： 1： 2： 185, crystallization temperature 85 ℃, crystallization time 8 h, n（THF）：n（Al2O3） =0.75：1.