文献类型：期刊文献

中文题名：硅凝胶小球上A型分子筛晶化动力学的研究

英文题名：Crystallization Kinetics of A Molecular Sieves on Pre-Prepared Silica Gel Pellets

作者：韩雪娇[1];孙辉[1];沈本贤[1]

机构：[1]华东理工大学化学工程联合国家重点实验室,上海200237

年份：2015

卷号：44

期号：9

起止页码：1071

中文期刊名：石油化工

外文期刊名：Petrochemical Technology

收录：CSTPCD;;Scopus;北大核心:【北大核心2014】；CSCD:【CSCD2015_2016】；

基金：国家自然科学基金项目(21201063)

语种：中文

中文关键词：油碱柱成型法;硅凝胶;黏结剂;分子筛;动力学

外文关键词：oil-alkali column moulding; silica gel; binder; molecular sieve; kinetics

摘要：采用常温油碱柱成型法制备硅凝胶小球,并在其上原位合成无黏结剂5A分子筛,考察晶化时间、晶化体系的碱度、晶化温度对晶化过程的影响,并拟合得到Avarami-Erofe′ev模型。XRD和SEM表征结果显示,晶化时间3 h时,晶化产物的晶粒呈规则的立方型,尺寸均一(直径约为400 nm),结晶度最高。实验结果表明,与传统水热转化合成法相比,采用该法合成的分子筛具有更快的晶化生长速率及较短的稳定期,高碱度能加快分子筛晶体的生长及其向方钠石晶体的转变;在n(SiO2)∶n(NaAlO2)∶n(NaOH)∶n(H2O)=1∶2∶1∶40、晶化时间3 h、晶化温度373 K、硅凝胶小球老化24 h的合成条件下,Avarami指数约为2、晶体生长表观活化能为81.1 k J/mol、指数前因子为4.5×1010,合成的分子筛比UOP含黏结剂5A分子筛对正己烷298 K的静态饱和吸附容量提高了20%。
Binderless 5A molecular sieves were synthesized in-situ on the silica gel pellets which were prepared by oil-alkali column moulding method at room temperature. The crystallinity and crystal morphology of the molecular sieves were characterized by means of XRD and SEM. The effects of crystallization time, alkaline concentration and crystallization temperature on the crystallization process were studied. Kinetics parameters for the Avarami-Erofe＇ev model were obtained by simulating the crystallization curves. The characterization showed that, at the crystallization time of 3 h, the obtained molecular sieves had the highest crystallinity with uniform crystalline size of about 400 nm. Compared to the traditional hydrothermal treatment, the in-situ crystallization on the silica gel pellets had rapid crystallization rate and short stable period. High alkali contention can promote the transformation of the 5A molecular sieves to sodalite crystals. Under the synthesizing conditions of n（SiO2） ： n（NaAlO2） ： n（NaOH） ： n（H2O） 1 ： 2 ： 1 ： 40, crystallization time 3 h, crystallization temperature 373 K and aging time 24 h, the simulated Avarami exponent, apparent activation energy for the crystal growth and pre-exponential factor are 2, 81.1 kJ/mol and 4.5 × 10^10, respectively. At the adsorption temperature of 298 K, the static saturated adsorption capacity of the synthesized binderless 5A molecular sieves is 20% larger than that of the UOP 5A molecular sieves and the bindefless 5A molecular sieves have a rapider adsorption rate for hexane.