摘要
研究了氟介质条件下,合成参数对前驱体黏度和无铝Beta分子筛晶化过程的影响. X射线衍射结果表明,高水硅比可降低前驱体的黏度,但抑制分子筛的晶化.当合成体系中加入成核促进剂（二氧化锗）和晶化促进剂（高氯酸根或磷酸根）后,即使水硅摩尔比高达20~30,在150℃水热合成4 d,仍可获得高结晶性、微米级球形或多面体形无铝Beta分子筛.热重和能谱分析结果表明,极少量高氯酸根和磷酸根可进入分子筛孔道,并影响模板剂四乙基铵根离子的热分解过程.氮气吸附-脱附、扫描电子显微镜、透射电子显微镜和选区电子衍射分析结果表明,所得无铝Beta分子筛具有多级孔结构,介孔尺寸在3.4~3.8 nm之间,由纳米晶体或纳米棒堆积而成.
The influence of various parameters upon the physical state of precursor and crystallization of alu-minum-free Beta zeolite were investigated in fluoride media. X-Ray diffraction（XRD） analysis showed that H2 O/SiO2 molar ratio in the precursor played an important role in the viscosity of precursor and the crystallization of aluminum-free Beta zeolite. High H2O/SiO2 molar ratio（〉10） was benefited to the precur-sor＇s viscosity but inhibited the crystallization process of aluminum-free Beta zeolite. While, high crystalline aluminum-free Beta zeolite with polyhedron or sphere morphology in micrometer scale could be obtained in the presence of nucleation promoter（ GeO2 ） and crystallization promoter such as ClO-4 and PO3-4 at 150 ℃ for 4 d, even though H2 O/SiO2 molar ratio was high to 20-30. The analysis of thermogravimetry and energy dispersive spectrometry proved that small amount of ClO-4 and PO3-4 maybe incorporated into the channel of Beta zeolite and influenced the thermal decomposition process of template （ tetraethyl ammonium cation ） . Further charac-terization for the morphology, crystalline and pore structure of the resultant aluminu-free Beta zeolite were carried out by environmental scanning electron microscope（SEM）, transmission electron microscope（TEM）, selected-area electron diffraction （ SAED ） and nitrogen adsorption-desorption isotherm. The results indicate that the obtained aluminum-free Beta zeolite is hierarchical structure, which constructed by nanoparticles or nanosheets. The mesoporous pore size is in the range of 3. 4-3. 8 nm.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2014年第2期215-223,共9页
Chemical Journal of Chinese Universities
基金
教育部长江学者和创新团队发展计划(批准号:IRT1070)
陕西省重点科技创新团队(批准号:2012KCT-21)
陕西省自然科学基金(批准号:2012JM2002)
陕西省科技攻关项目(批准号:2012K08-09)
中央高校团队项目(批准号:GK261001108
GK261001009)
中央高校基本科研业务费专项资金(批准号:GK201101003
GK201302036
GK201302037)资助~~
关键词
高水硅比
晶化条件
多级孔结构
无铝Beta分子筛
High H2 O/SiO2 molar ratio
Crystallization parameter
Hierarchical structure
Aluminum free Beta zeolite
