摘要
采用静态水热晶化法 ,在Na2 O Al2 O3 SiO2 HMI H2 O(HMI :六亚甲基亚胺 )体系中 ,在HMI/SiO2 摩尔比为 0 0 9,H2 O/SiO2 摩尔比为 12 ,晶化时间为 6 0～ 80h的条件下 ,合成了MCM 2 2分子筛 .利用固体硅胶表面的吸附性能提高模板剂的局部浓度 ,从而实现了分子筛的高效合成 .对合成条件的研究结果表明 ,以比表面积 (4 86m2 /g)大、反应性能好的硅胶为硅源是静态水热晶化法高效合成MCM 2 2分子筛的关键 ,而成胶老化方式对MCM 2 2分子筛的晶化影响不大 .产物的晶相和转晶的类型取决于合成凝胶的初始硅铝比 .当SiO2 /Al2 O3 摩尔比 =18～ 80时可以合成出MCM 2 2 ,当SiO2 /Al2 O3 =13～ 17时可以合成出MCM 49.硅铝比较低 (如SiO2 /Al2 O3 =2 0 )时 ,MCM 2 2分子筛易转晶为MOR分子筛 ,而在硅铝比较高 (如SiO2 /Al2 O3 =5 0 )时 ,可转晶为ZSM
Zeolite MCM-22 has been synthesized under static hydrothermal crystallization conditions using silica gel, sodium aluminate and hexamethyleneimine (HMI), The typical crystallization conditions are HMI/SiO2 molar ratio of 0.09 similar to 0.2, H2O/SiO2 molar ratio of 12 similar to 20 and crystallization time of 60 similar to 80 h. The template to silica ratio and water to silica ratio arc much lower than those in the literature. The utilization of silica gel with high surface area (486 m(2)/g) and high activity as the silica source is the key to the highly efficient Synthesis of MCM-22, while the aging step during the preparation of gel is not closely related to the synthesis. The investigation of the crystallization conditions indicates that the product obtained and its trans-crystallization depend on the SiO2/Al2O3 ratio of the get system. When the SiO2/Al2O3 ratio equals to 18 similar to 80, the product is MCM-22, which may be trans-crystalized into ZSM-5 at a higher SiO2/Al2O3 ratio such as 50 and into MOR at a lower SiO2/Al2O3 ratio such as 20; when the SiO2/Al2O3 ratio equals to 13 similar to 17, MCM-49 is produced.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2002年第5期439-442,共4页
基金
国家重大基础研究规划项目 (G2 0 0 0 480 0 0 1)
