摘要
分别以工业级的偏铝酸钠和水玻璃为铝源和硅源,氢氧化钠为主要碱源,氢氧化钾为辅助碱源,采用LSX晶种法制备了LSX型分子筛。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线荧光(XRF)、傅里叶变换红外光谱(FTIR)和N2吸附-脱附等表征方式考察了有无晶种、钾钠物质的量之比、晶化条件对合成LSX型分子筛的影响。结果表明,加入LSX晶种不仅能显著缩短晶化时间,提高分子筛的结晶度,还可有效抑制方钠石和A型杂晶的伴生;钾钠比过高或过低均会造成A型或方钠石型杂晶的伴生;直接进行高温晶化会导致亚稳态的LSX型分子筛向热力学稳定相转变;延长老化时间或高温晶化处理降低了产物中的硅铝比;样品的比表面积和N2吸附量随老化时间的延长和高温晶化处理而逐渐下降。
Influencing factors for the synthesis of LSX molecular sieve, such as LSX seed, nK/nNa and crystallization conditions were investigated in detail. The products were characterized by XRD, SEM, XRF, FTIR and N2 adsorption-desorption. The results revealed that the addition of LSX seed could accelerate the rates of crystal nucleation and growth, and inhibit the formation of A type and sodalite zeolites. Furthermore, too high or too low value of nK/nNa in the synthesis gel would obtain A type and sodalite impurities. Crystallization at high temperature directly would lead the conversion of metastable LSX zeolite into more thermodynamically stable zeolite phase. The Si-Al ratio, the surface area and N2 adsorption capacity of the end product decreased with the extending of aging time and the increasing of crystallization temperature.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2016年第11期1995-2002,共8页
Chinese Journal of Inorganic Chemistry
基金
国家自然科学基金(No.41206067)资助项目
关键词
LSX分子筛
晶种法
低成本
高效率
LSX molecular sieve
seeding method
low-cost
high efficiency