ZSM-5/MCM-41微-介孔复合分子筛的微波合成及表征

Microwave Synthesis and Characterization of Composite Micro-Mesoporous ZSM-5/MCM-41 Molecular Sieves

以碱液处理的ZSM-5分子筛反应液为硅铝源、十六烷基三甲基溴化铵为介孔模板剂,通过微波法快速合成了具有微-介孔结构的ZSM-5/MCM-41复合分子筛。考察了反应时间、反应温度和体系p H对合成产物的影响,优化了合成条件,并利用XRD、SEM、TEM、N2吸附-脱附等手段对合成产物进行了表征。实验结果表明,反应温度为120℃时,在0.5 mol/L的Na OH溶液中,利用微波消解ZSM-5分子筛原粉30 min后,调节体系p H为10.5,继续晶化30 min,可得到ZSM-5/MCM-41复合分子筛。相比于传统水热法,微波法的合成效率提高了20倍以上。所得ZSM-5/MCM-41复合分子筛中既保留了ZSM-5分子筛的微孔结构,也形成了典型的MCM-41分子筛的介孔结构,且所得ZSM-5/MCM-41复合分子筛的孔体积、比表面积较ZSM-5分子筛提高了近3倍。

Composite ZSM-5/MCM-41 molecular sieves with micro-mesoporous structure were synthesized with cetyl trimethyl ammonium bromide as template and alkali-treated ZSM-5 serifl ux as the sources of silica and aluminum by means of microwave technique. The products were characterized by means of XRD,SEM,TEM and N2 adsorption-desorption. The effects of reaction temperature,reaction time and the system p H on the pore structure of the products were investigated. The results showed that,under the optimized synthesis conditions of Na OH solution concentration 0.5 mol/L,dissolving ZSM-5 zeolite by means of microwave irradiation at 120 ℃ for 30 min,and then the system p H 10.5 and crystallizing time 30 min,the composite ZSM-5/MCM-41 molecular sieves could be synthesized. Compared to the traditional hydrothermal method,the microwave method improved the synthesizing efficiency more than 20 times. There are both the microporous structure of ZSM-5 molecular sieves and the mesoporous structure of MCM-41 molecular sieves in the products. Compared to those of the ZSM-5 zeolite,both the pore volume and the specific surface area of the composite ZSM-5/MCM-41 molecular sieves increased by 3 times.