摘要
采用水热合成法,以N,N-二异丙基乙胺为模板剂合成SAPO-18分子筛,并用X射线衍射、X射线荧光光谱、扫描电子显微镜、NH3程序升温脱附及N2吸附-脱附等对其结构进行表征,系统研究合成凝胶中硅源用量对SAPO-18分子筛合成及其在甲醇制烯烃反应中催化性能的影响。结果表明,在晶化温度453 K、晶化时间96 h和合成凝胶中0.3≤n(Si O2)∶n(Al2O3)≤1.2条件下,能合成出纯相的SAPO-18分子筛,其中,当n(Si O2)∶n(Al2O3)=0.6,在反应时间135 min时,合成的SAPO-18分子筛具有较高的双烯选择性(乙烯+丙烯)。合成凝胶中硅源的用量对SAPO-18分子筛酸性有显著影响,适当增加分子筛中强酸比有助于提高乙烯和丙烯选择性,但缩短催化剂寿命。
Using N, N-diisopropylenthylamine as the structure-directing agent, SAPO-18 molecular sieves were synthesized by hydrothermal method. The physieochemical properties of the as-prepared molecular sieves were characterized by XRD, XRF, SEM, NH3-TPD and N2 adsorption-desorption. The effect of silicon amounts on physicoehemieal properties and catalytic performance of SAPO-18 molecular sieves in MTO reaction was investigated. The results showed that under the condition of crystallization temperature 453 K, crystallization time 96 h, and 0.3≤n （ SiO2 ）：n （ Al2O3 ）≤1.2 in initial gel, pure SAPO-18 molec- ular sieve was obtained;SAPO-18 molecular sieve prepared with n（ SiO2）：n（A1203 ） = 0.6 had the high- est selectivity to （ ethylene ＋ propylene） under reaction time 135 min. The silicon amounts in initial gel had remarkable influence on the acidity of SAPO-18 molecular sieves. Increasing appropriately the ratio of strong acid in molecular sieves helped to improve the selectivity to ethylene and propylene, but shortened the service time of the catalyst.
出处
《工业催化》
CAS
2015年第5期384-389,共6页
Industrial Catalysis
关键词
催化剂工程
SAPO-18分子筛
硅源
甲醇制烯烃
催化性能
catalyst engineering
SAPO-18 molecular sieve
silicon source
methanol to olefins
catalytic property
