共查询到18条相似文献,搜索用时 62 毫秒
1.
氟离子对无胺法合成高硅丝光沸石的结构导向作用 总被引:4,自引:0,他引:4
在含氟无胺体系中合成了高硅丝光沸石,研究了合成条件对丝光沸石产物的影响.结果表明,投料n(SiO2)/n(Al2O3)=20~200时,控制晶化条件可得到高硅丝光沸石纯相.由含氟无胺体系中丝光沸石的热力学稳定相区可见,氟离子的引入对方沸石的生成的相区无影响,ZSM-5和镁碱沸石生成的相区消失,丝光沸石生成的相区扩大,石英生成的相区缩小,且基本上变为两相共存区.合成产物丝光沸石的硅铝比随着氟硅比的升高同步增大,证明氟离子在无胺合成高硅丝光沸石时具有结构导向作用. 相似文献
2.
无胺体系高硅铝比丝光沸石的合成 总被引:1,自引:0,他引:1
Mordenite has two kinds of pore channels. The main straight channels of 0.67 nm ×0.70 nm (12-membered ring) parallel to the caxis are interconnected with small side-channels of 0.29 nm×0.57 nm (8-membered ring) parallel to the baxis. 相似文献
3.
干法合成纯硅丝光沸石 总被引:2,自引:0,他引:2
在Na2O-SiO2-EA体系中利用干法首次成功地合成了纯硅丝光沸石,采用XRD,SEM及IR等仪器分析方法对产物的结构,形貌,红外有架振动及稳定性等进行了表征。实验结果表明,干法合成的纯硅丝光沸石具有良好的耐酸性;与水热体系合成的丝光沸石相比,干法得到的丝光沸石的晶胞体积出现较明显的收缩趋势。 相似文献
4.
5.
丝光沸石合成与表征的研究进展 总被引:8,自引:0,他引:8
丝光沸石 ( MOR)是人类认识最早的沸石之一 ,分天然和合成两类 .1 864年 How首次命名天然丝光沸石[1] . 1 948年 ,Barrer等 [2 ] 用碳酸钠为矿化剂 ,使混合硅酸凝胶与铝酸钠水溶液在 2 65~ 2 95℃下水热晶化 ,首次合成出丝光沸石 .丝光沸石具有优良的耐热、耐酸和抗水汽性能 ,工业上广泛用作气体或液体混合物分离的吸附剂及石油化工与精细化工催化剂 .1丝光沸石结构丝光沸石中由 5~ 3结构单元连接的四元环和五元环 (五元环占优势 )构成椭圆形 1 2元环主通道 ,主通道间有八元环通道沟通 .1 2元环直筒形通道尺寸 0 .695× 0 .5 81 nm,八元… 相似文献
6.
7.
9.
10.
11.
采用热涂-浸渍法在大孔α-Al2O3载体上形成薄且致密的晶种层,然后在不添加有机模板剂的含氟条件下二次水热生长法制备了高性能丝光沸石分子筛膜,考察了NaF含量、硅/铝比对丝光沸石分子筛膜形貌和性能的影响.将摩尔组成为6Na2O:1.2Al2O3:30SiO2:780H2O:1.5NaF条件下合成的丝光沸石分子筛膜用于渗透汽化分离91.5%乙醇/水体系,在渗透汽化温度70°C、真空度为400Pa条件下,分离因子和通量分别达到了6872和0.51kg/(m2·h);另外,在分离异丙醇/水、乙酸/水体系时,渗透侧水浓度达到了100%(在色谱检测极限范围内),该分离系数是目前报道的丝光沸石分子筛膜分离的最佳值,并在乙酸浓度为1mol/L的乙醇水溶液中表现出良好的耐酸性.该膜有望作为膜反应器在乙酸乙酯等酯类的生产中大大提高转化率. 相似文献
12.
以四丁基氢氧化磷为模板剂, 在中温水热条件下, 利用浓溶胶法合成了具有一维18元环孔道的含铝硅锗酸盐分子筛ITQ-33. 系统研究了ITQ-33的合成条件, 并利用原位变温X射线衍射(XRD), 扫描电子显微镜(SEM), 固体核磁共振波谱(NMR), 电感耦合等离子体发射光谱(ICP), 氮气吸附-脱附程序升温脱附(TPD), 热重(TG)及元素分析等手段对其结构、 稳定性及催化性能进行了表征. 结果表明, 以季磷化合物为模板剂可以合成含铝的ITQ-33纯相, 产物具有较高的热稳定性, 其骨架结构可以稳定至400℃以上, 煅烧后的ITQ-33具有Lewis酸位点, 在酸催化方面有潜在的应用价值. 相似文献
13.
LIANG Jun FU Wenhua LIU Chuang LI Xiangcheng WANG Yu MA Duozheng LI Yuekun WANG Zhendong YANG Weimin 《高等学校化学研究》2022,38(1):243-249
This paper describes the synthesis of FER zeolite using commercially available 4-(aminomethyl)pyridine as organic structure-directing agent(OSDA). FER zeolites were prepared in mixtures with SiO2/Al2O3 molar ratios in a narrow range and the resultant products possessed a typical flake-shaped morphology. The crystallization of FER zeolite was tracked in order to better understand the formation mechanism and the products obtained at different crystallization time were systematically characterized using multiple techniques. It showed that a majority of Si atoms and nearly all the Al atoms transformed into the solid phase during the hydrothermal synthesis. The rearrangement of inorganic species gave rise to zeolitic 5-membered rings(5-MRs) and 6-membered rings(6-MRs). Consequently, FER zeolite crystals were formed by the consumption of amorphous bulky gel/solid matrix. Tracking the synthesis process of FER can help. 相似文献
14.
H. Bargozin 《Journal of Dispersion Science and Technology》2013,34(10):1454-1464
This work studies the stability of silica aerogel aqueous dispersion for wettability alteration in enhanced oil recovery (EOR) processes. Modified silica aerogel is synthesized with cheap water glass as the precursor, and ambient pressure drying method. Brine composition, brine concentration and temperature of oil reservoirs are the most important parameters for success of wettability alteration processes in EOR. Stability of Silica aerogel aqueous dispersions in NaCl, MgCl2 and combinations of them are surveyed. Brines at different concentrations, 10000, 20000, 40000 ppm, are used to determine stability conditions. Stability at 30°C and 75°C are surveyed, and the results are reported. DLVO and non-DLVO theories are used for modeling the stability of nanodispersion. 相似文献
15.
碱溶法制备高孔隙度多孔微球 总被引:2,自引:0,他引:2
提出并研究了以碱溶侵蚀提高多孔硅球孔隙度的新方法,研究了碱液浓度、处理温度、反应时间与洗除量的关系。结果表明,随着NaOH浓度的提高,不仅洗除量加大,而且硅胶的溶解速度亦少许增大,其主要原因是由于某些孔结构的塌陷导致了细屑的脱除。温度升高和处理时间延长会导致洗除量增大。随着洗除量的增加,硅胶的比孔容呈线性增大,但其外观仍为均匀的球形,且直径亦未见明显变化。选用粒径4~5 μm、孔径8 nm、比孔容1.4 cm3/g的多孔硅胶,采用1.25 mol/L NaOH水溶液、室温(25 ℃)处理3.0 h,制备了粒径4~5 μm、孔径14 nm、比孔容3.2 cm3/g的高孔隙度多孔硅胶,其孔隙度从75%增加到88%。 相似文献
16.
Combustion of the rice husk produces rice husk ash, which consists of mainly silica. High purity silica can be produced by controlled combustion after acid treatment. In this study, leaching of rice husk with hydrochloric acid and sulfuric acid were carried out prior to combustion to obtain purer silica. It was found that pre-treatment of the rice husk with sulfuric acid had accelerated the hydrolysis and decomposition of organic components as revealed by thermogravimetry (TG) and Scanning Electron Microscopy (SEM) analyses. In a systematic study, the combustion of un-leached, hydrochloric acid-leached and sulfuric acid-leached rice husks were performed in a muffle furnace at 500, 600, 700, 800 and 900oC for 2 h. Results demonstrated that all the samples produced amorphous silica (SiO2) and the average particle size were in the range of 0.50 to 0.70 μm. The effect of combustion at different temperatures between 500oC and 900oC on the silica production is very small, particularly at temperature above 600oC. Thus, amorphous silica with purity above 99% as confirmed by X-Ray Fluorescence (XRF) analysis can be produced by hydrochloric and sulfuric acids leaching of the rice husk, followed by controlled combustion at 600oC for 2 h. The BET surface area of the silica produced after leaching the rice husk with hydrochloric acid was higher (218 m2/g) than with sulfuric acid (209 m2/g). The silica obtained has potential application as filler in plastics and rubber compounding. 相似文献
17.
18.
阳离子与非离子混合表面活性剂模板合成介孔SiO2 总被引:9,自引:0,他引:9
利用各种两亲分子有序组合体构成超分子模板,合成从介观到宏观尺度不同形态的无机材料成为材料科学新崛起的研究方向[1].介孔SiO2在催化、吸附、分离介质及化学传感器等方面有广阔的应用前景. 相似文献