无溶剂热处理固相转化法简易制备沸石咪唑酯骨架材料

设计开发了一种无需溶剂,通过热处理固相转化制备沸石咪唑酯骨架材料(ZIFs)的简易方法.该方法无需溶剂及其它预处理,只需将金属源与有机配体固相混合后于低温(200℃)热处理即可实现多孔晶体材料的制备.所合成材料H-ZIF-67为具有方纳石拓扑结构的纳米晶体,与传统方式合成的ZIFs材料一致.粉末X射线衍射(PXRD)分析结果表明产物的晶体结构与标准ZIFs谱图一致.通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、N₂吸附-脱附分析、热重分析(TGA)和傅里叶变换红外光谱(FTIR)等手段对合成的材料进行了表征,发现H-ZIF-67材料具有与ZIFs材料类似的特性.该方法经济、高效,摒弃了传统方法合成ZIFs材料周期长、处理过程复杂的弊端,为ZIFs材料的量产提供了新思路.     

气固相法制备含钛丝光沸石

以脱铝丝光沸石为母体,采用气固相法合成了含钛丝光沸石,ＩＲ及ＵＶ－Ｖｉｓ光谱表明,以浓ＨＮＯ３深度脱铝样品,钛进入沸石骨架,且以四配位形式存在,具有较好的环己烯环氧化性能;而以稀ＨＮＯ３处理的样品,进入骨架的量较少,大部分以非骨架钛形式存在,环己烯环氧化性能较差。     

水合NaX沸石与碱金属盐类间的固相离子交换

通过XRD和吡啶吸附的IR技术考察了水合13X沸石与碱金属盐类间的固相离子交换反应,结果表明,此类固相离子交换在室温下即可发生。一次交换的程度有限,通过重复交换可提高交换度,体积较大的Cs⁺比K⁺难于交换,高温焙烧有利于提高Cs⁺的交换度。     

蒸汽相法硼硅MFI沸石的合成与表征

在三乙胺（Ｅｔ３Ｎ）－乙二胺（ＥＤＡ）－Ｈ２Ｏ蒸汽相中,无定形凝胶Ｎａ２Ｏ－Ｂ２Ｏ２－ＳｉＯ２－Ｈ２Ｏ晶化生成硼硅ＭＦＩ（ＺＳＭ—５）沸石．研究了硼硅ＭＦＩ沸石的适宜晶化条件,以及氯化钠、碳酸钠和磷酸钠取代氢氧化钠作为钠源的影响．晶体结构参数、１１ＢＮＭＲ、ＦＴ－ＩＲ的结果表明,由蒸汽相法合成的硼硅ＭＦＩ沸石,其硼原子进入了沸石骨架．     

蒸汽相转化法原位诱导沸石化制备Y-ZSM-5双沸石复合物

针对Y型沸石在ZSM-5沸石干胶制备及晶化过程中易于溶解、坍塌的问题,采用葡萄糖在水热处理条件下对Y沸石进行包膜处理,提高了Y沸石在高温、高碱度环境中的稳定性,并采用蒸汽相转化法制备了同时含有Y和ZSM-5的双沸石复合物。对影响沸石复合物形成的因素如Y沸石表面碳包膜改性、凝胶碱度、晶化时间等进行了详细讨论。采用X射线衍射（XRD）、扫描电子显微镜（SEM）、傅立叶变换红外（FT-IR）、N₂吸附-脱附,能谱（EDS）以及NH₃-TPD等手段对制备的材料进行了表征。结果表明通过蒸汽相转化法能获得Y和ZSM-5两相共存的双沸石复合物,产物中的ZSM-5沸石相前驱体随蒸汽处理时间的延长逐渐从蠕虫状无定型向纳米多晶ZSM-5沸石转变,纳米多晶聚集体与Y型沸石晶粒之间紧密相连,相互包埋。在异丙苯催化裂化反应中,合成的沸石复合物的活性和稳定性介于Y和ZSM-5之间,优于对应的机械混合物。     

B-Al-ZSM-5沸石的固相结晶过程和机理的研究

用11B ,2 7Al,2 9Si,13 CMASNMR ,XRD ,IR技术详细研究了B2 O3 ·Al2 O3 ·SiO2 干凝胶在乙胺 /H2 O混合蒸气相中 ,固相转晶生成B Al ZSM 5沸石的过程和机理 .干胶中非网络的三配位硼氧基团在转晶过程中起着非常重要的作用 .结晶过程中Al原子周围的化学环境变化很复杂 ,干胶及最终沸石产物中都不存在的六配位铝只在半晶化产物中出现 .硅主要以羟基化合物形式存在于干胶中 ,反应过程中出现的非结构硅氧基团在完全晶化时消失 .既是反应物又是模板剂的乙胺分子通过氢键与干胶表面的硼羟基、铝羟基和硅羟基结合形成前驱体 ,促进了结晶过程 .经11BMASNMR和IR谱的测定 ,固相转晶生成的B Al ZSM 5沸石相对结晶度为 93%左右 .     

蒸汽相转化法原位诱导沸石化制备Y-ZSM-5双沸石复合物

针对Y型沸石在ZSM-5沸石干胶制备及晶化过程中易于溶解、坍塌的问题,采用葡萄糖在水热处理条件下对Y沸石进行包膜处理,提高了Y沸石在高温、高碱度环境中的稳定性,并采用蒸汽相转化法制备了同时含有Y和ZSM-5的双沸石复合物。对影响沸石复合物形成的因素如Y沸石表面碳包膜改性、凝胶碱度、晶化时间等进行了详细讨论。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、傅立叶变换红外(FT-IR)、N2吸附-脱附,能谱(EDS)以及NH3-TPD等手段对制备的材料进行了表征。结果表明通过蒸汽相转化法能获得Y和ZSM-5两相共存的双沸石复合物,产物中的ZSM-5沸石相前驱体随蒸汽处理时间的延长逐渐从蠕虫状无定型向纳米多晶ZSM-5沸石转变,纳米多晶聚集体与Y型沸石晶粒之间紧密相连,相互包埋。在异丙苯催化裂化反应中,合成的沸石复合物的活性和稳定性介于Y和ZSM-5之间,优于对应的机械混合物。     

无胺体系高硅铝比丝光沸石的合成

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.     

Preparation of Silicalite-1 Within Macroporous Silica Glass

Microcrystalline silicalite-1 was formed on the inner surface of macroporus silica glasses prepared by the sol-gel process. By heating a homogeneous precursor solution at 100°C under a hydrothermal condition, 2–5 m of plate-like particles of silicalite-1 were deposited. With an increase of mixing time of the precursor solution, the number of silicalite-1 particles increased, accompanied by the relative decrease of the particle size. Depending on the temperature and the duration of the heat-treatment of the macroporous silica, the amount of deposited silicalite-1 varied. Below 1000°C, the amount increased with the heat-treatment temperature, as a result of the competition between the precipitation of silicalite-1 and the dissolution of silica from the macroporous silica glass under a strongly basic condition. On the other hand, above 1000°C the amount of deposited silicalite-1 decreased in accordance with the decrease of the macropore diameter by the heat-treatment, because of the limited transport of the dissolved silicate species through the smaller macropores.     

ZSM-5／Silicalite-1核壳分子筛含氟水热体系的合成及表征

以圆柱形ZSM-5为核,用柠檬酸对其外表面进行预处理后,在含氟壳层晶化体系中二次生长合成核壳分子筛.通过X射线衍射、扫描电镜、透射电镜、N2吸附及氨程序升温脱附对分子筛进行了表征,并以甲苯歧化和1,3,5-三甲苯裂化为探针反应对分子筛性能进行了考察.结果显示,产物是以ZSM-5为核、silicalite-1纳米晶为壳的两相复合微孔分子筛材料;在含氟体系中ZSM-5外延生长出了致密壳层;全硅壳层的覆盖度约达到97%,核壳分子筛的外表面酸位随之减少,但基本保持孔道内的酸性。     

应用表面光电压谱研究固体表面酸度

测量与亚带隙辐射相关的表面光电压谱可极其灵敏地得到固体表面态信息。固体表面酸与受体表面态相关。本文用近红外光辐射测试了分子筛和杂多酸的表面光电压,观察到在900～1500 nm光谱区有表面光电压响应。不同的峰位对应不同受体表面态位置,代表不同酸的强度;峰强度对应态密度,反映了酸总量。对初步结果也进行了理论分析。     

Equilibrium Adsorption of Light Alkanes in Silicalite-1 by the Inertial Microbalance Technique

The equilibrium adsorption of the light alkanes methane, ethane, propane, n-butane, and i-butane in silicalite-1 has been investigated using the TEOM technique. Either a conventional or a dual-site Langmuir isotherm appropriately describes the equilibrium data. Good agreement with the literature data determined by other techniques indicates the TEOM is a reliable technique. The adsorption of i-butane in silicalite-1 reveals the discrete preferential molecular siting, implying a discrete-dual-structural heterogeneity for light alkanes in silicalite-1.     

Synthesis and separation performance of silicalite-1 membranes on silica tubes

High-performance silicalite-1 membranes were synthesized on silica tubes by in-situ hydrothermal synthesis. By using the "solution-filling (SF)" method, the average flux of membranes with the SF method was improved by about 25% compared to that of the membranes without using the SF method; the flux and the separation factor of the membranes prepared with the SF method for an ethanol/water mixture at 60 ℃ were 0.99 kg/(m2·h) and 73, respectively. It was found that the membranes synthesized on silica tubes ex...     

Metal Sorption,Solid Phase Extraction and Preconcentration Properties of Two Silica Gel Phases Chemically Modified with 2-Hydroxy-1-Naphthaldehyde

Active silica gel phase (I) was chemically modified to the corresponding amino- (SiNH₂) and chloro- (SiCl) derivatives via silylation reactions. These were used to synthesize two newly modified silica gel phases (II, III) by direct chemical reaction with 2-hydroxynaphthaldehyde (2-HNA). The surface coverage values are 370, 432µmolg^–1 and 320, 355µmolg^–1 for (II) and (III), on the basis of thermal desorption and metal probe testing method, respectively. The metal sorption properties of silica gel phases (II, III) were studied and compared with active silica gel phase (I). The maximum determined metal capacity values were found to be 10–110, 20–290 and 20–370µmolg^–1 for phases I, II and III, respectively. The distribution coefficient values (K_d) were also determined for a series of metal ions, and the results showed that the two new chemically modified phases (II and III) were highly selective for Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺ and Pb²⁺. The potential applications of silica gel phases (II, III) as solid phase extractors for the same five metal ions spiked in drinking tap water (1.000µgmL^–1) were found to give percentage recovery values in the range of 90.2–96.3±4.1–6.3%, while pre-concentration of the same five metal ions spiked in drinking tap water (50.0ngmL^–1) was successfully accomplished with a percentage recovery range of 92.6–95.8±4.8–5.7%.Received December 16, 2002; accepted May 14, 2003 published online September 1, 2003     

Preparation and pervaporation performance of high-quality silicalite-1 membranes

High-performance silicalite-1 membranes were successfully synthesized on novel porous silica tubes by two-step in-situ hydrothermal synthesis.The flux and separation factor towards ethanol/water mix- ture at 60℃were 0.56 kg/(m2·h)and 84,respectively.The as-synthesized silicalite-1 membranes were characterized by scanning electron microscopy(SEM).The influence of different synthesis conditions on the separation performance of the silicalite-1 membranes was investigated.It was found that the average flux of silicalite-1 membranes was improved by about 26?ter filling the silica tubes with mixed solution containing glycerol and water.After calcinating at 400℃for 5 h repeatedly,membrane synthesized on silica tube still showed high pervaporation performance towards ethanol/water mixture even at a calcination rate of 4℃/min,which suggested that silica support was more suitable for pre- paring high-performance silicalite-1 membranes.     

Preparation and catalytic activity of titanium silicalite-1 zeolite membrane with TPABr as template

The preparation of the supported titanium silicalite-1 (TS-1) zeolite membrane with inexpensive tetrapropylammonium bromide (TPABr)/weak base synthesis system was studied by three methods, and the catalytic activity of the obtained TS-1 zeolite membrane was evaluated with the oxidation of 2-propanol (IPA) under pervaporation condition. It was found that TS-1 zeolite membrane could be successfully prepared with “seeding” or “seeding in situ” method, but could not be achieved with “in situ” method. Adding a little amount of promoter ions of PO₄³⁻ into the synthesis gel was of benefit to the catalytic activity of the prepared TS-1 zeolite membrane, but had no obvious effect on the membrane layer formation on the mullite porous support. For “seeding” method, the membrane prepared with the synthesis gel having molar composition of SiO₂:0.1TPABr:0.9Et₂NH:0.03TiO₂:80H₂O:0.06H₃PO₄ at 150 °C for 48 h showed the highest oxidation conversion of IPA of 72% accompanied by a flux of 0.35 kg/m² h. Further more, much higher IPA oxidation conversion of 76% accompanied by a flux of 0.65 kg/m² h was obtained for the TS-1 zeolite membrane prepared with the same synthesis gel by “seeding in situ” method at 150 °C for 72 h.     

二氧化硅表面的APTS修饰

3-氨丙基三乙氧基硅烷(APTS)修饰的二氧化硅在生物化学、分析、催化、电子学等领域具有重要的应用前景。本文对近年来APTS修饰二氧化硅的研究进展进行了简要的概述,介绍了APTS修饰二氧化硅的典型方法和APTS修饰层的表征手段,探讨了不同修饰方法可控性及对所形成的APTS层结构及稳定性的影响。     

Synthesis of titanium silicalite-1 (TS-1) zeolite with high content of Ti by a dry gel conversion method using amorphous TiO2–SiO2 composite with highly dispersed Ti species

In this study, we have developed a new method to synthesize mesoporous titanium silicalite-1 (TS-1) with a higher content of active titanium in the framework (more than 5%) than that obtained from the conventional hydrothermal synthesis. The new method combines two methods as follows: (1) a sol-gel method in tetrahydrofuran for the synthesis of TiO₂–SiO₂ composite with highly dispersed Ti species and (2) a dry gel conversion method for the crystallization to TS-1. This investigation revealed that the dispersion of Ti in the starting materials was quite important to synthesize mesoporous TS-1 with high content of Ti besides dry conversion method. The obtained mesoporous TS-1 with a high content of titanium showed higher catalytic activity in 1-hexene epoxidation than conventional TS-1. This high activity is likely to originate from the high content of titanium in the framework.