摘要
考察了不同的pH值、模板剂用量、用水量和升温程序等条件下合成的ZSM-5分子筛的形貌变化.结果表明:pH值在9.5～12.5范围内,随pH值逐渐变大,合成的分子筛晶粒尺寸逐渐增大,晶粒表面逐渐由粗糙趋于光滑;模板剂用量与硅源摩尔比从0.25∶1增加到0.4∶1时,分子筛由晶面较光滑的单个立方体晶粒变成表面粗糙的球形晶粒.用水量与硅源摩尔比(简称水硅比)由高到低时,分子筛由尺寸较小、均匀规整的无团聚晶粒渐变为粒径较大、晶形不规整且团聚严重的晶粒.无低温诱导期时,合成的分子筛晶粒尺寸较大,晶形呈立方体形,晶粒表面较光滑,部分晶粒表面出现明显的台阶纹;随着低温诱导期增长,晶粒表面的台阶纹长大,分子筛的晶形逐渐由立方体形变成圆球形,但表面台阶纹仍很明显;当低温诱导期达到一定时间,分子筛晶粒完全变成圆球形,且尺寸变小,表面粗糙,已无明显的台阶纹,即无明显的晶面.当晶体生长阶段温度逐渐升高时,晶体粒径逐步变大,结晶度逐渐升高.
Morphology studies were carried out for ZSM-5 molecular sieves synthesized under different conditions including pH value, template dosage, water consumption and temperature-controlling procedure. The results show that the particle sizes of ZSM-5 gradually become bigger and the crystal surface smoother when pH value increases from 9.5 to 12.5. As the template dosage vs silicon source molar ratio increases from 0.25:1 to 0.4:1, the molecular sieves change from smooth-surface separate cubic particles into coarse-surface spherical particles. When the molar ratio of water and silicon source gradually decreases, the small, regular and separate crystals grow up to bigger and irregular conglomerate. Furthermore, the molecular sieves change from bigger cubic smooth-surface crystals to smaller spherical coarse-surface multi-crystals with obvious boundaries as low temperature inducement stage increases gradually. And the higher the temperatures increase during crystal growth stage, the bigger the particle sizes of molecular sieves are and the higher the crystallization are obtained.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2005年第2期180-185,共6页
Journal of The Chinese Ceramic Society
基金
国家"973"计划项目(2003CB615806)
国家自然科学基金(40172018)资助项目。
关键词
ZSM-5分子筛
形貌
晶粒
合成条件
Crystal growth
Crystalline materials
Crystallization
Morphology
Particle size analysis
pH
Synthesis (chemical)
