采用改进的二次生长法在多孔α-Al_2O_3陶瓷管上合成Silicalite-1沸石膜

以钛溶胶分散Silicalite-1沸石晶种,采用提拉法在α-Al2O3陶瓷管上负载晶种层,通过二次水热合成在多孔α-Al2O3陶瓷管上制备Silicalite-1沸石膜。考察了晶种悬浮液中晶种的含量、提拉次数和制膜合成液的水与正硅酸乙酯摩尔比对Sili-calite-1沸石膜性能的影响。采用扫描电子显微镜和X射线衍射方法对Silicalite-1沸石膜的形貌和结构进行了表征。实验结果表明,制膜条件对Silicalite-1沸石膜渗透性能有较大影响;适宜的制膜条件为:制膜合成液的水与正硅酸乙酯摩尔比120、晶种悬浮液中晶种的质量分数10%、提拉次数6次。所合成Silicalite-1沸石膜表面连续、致密、与陶瓷管结合紧密;在323K、0.1MPa压差的条件下,Silicalite-1沸石膜的H渗透速率为7.36×10-7mol/(m2·s·Pa),H/SF理想分离因数为28.6。

Study on Crystallization of Titanium Silicalite(Ⅰ)

In order to investigate the rules on preparation of titanium silicalite （TS-1） the ^1H →^13C CP/ MAS NMR spectrometers were applied to track the function of template TPAOH in the process of crystallization of titanium silicalite. The research results revealed that at the initial stage of crystallization the TPA＋ ions acting as the template could predominantly absorb the polymers of negatively charged silicatitania sol and the interactions between silica sol and titania sol could gradually lead to the formation of tiny crystal nuclei that could slowly grow up to form molecular sieves. Upon investigating the course of crystallization of titanium silicalite the ^1H →^13C CP/MAS NMR spectrometers were applied to effectively enhance the resolution of 29Si signals in the titanium silicalite. Study results have shown that during the formation of tiny crystal nuclei upon interaction between titania sol and silica sol the influence of titania sol on the silica sol was insignificant. However, when tiny crystal nuclei broke out into molecular sieves the titania sol could enter the zeolite framework that could apparently impose an enhanced effect on the silica sol.

Study on Crystallization of Titanium Silicalite Zeolite (Ⅱ)

In order to investigate the rules on formation of zeolite during crystallization of titanium silicalite zeolite (TS-1) the X-ray diffractometry and Foulier transform infra-red spectrometry were applied to track the process of crystallization of titanium silicalite zeolite. The research results revealed that at the initial stage of crystallization the interactions between silica gel and titania gel in the polymer blend could gradually lead to the formation of tiny crystal nuclei with complicated structure that could slowly grow up to form molecular sieves. Quite different from the conventional zeolites that use the acid sites as the catalytically active centers, the oxidative reactivity of the titanium silicalite zeolite was not proportional to its crystallinity and is associated with the oxidative centers of titanium contained in the zeolite.

负载型TS-1沸石膜催化剂的制备、表征及其催化性能研究

利用水热合成法在α-Al_2O_3陶瓷管表面制备了连续完整的钛硅(TS-1)沸石膜,并且利用该膜催化剂催化丙烯直接环氧化合成环氧丙烷(PO)。采用SEM、XRD、FT-IR和UV-Vis等表征手段及丙烯环氧化反应测试,详细研究了合成液中Ti/Si比对TS-1沸石膜形貌、结构及催化性能的影响。结果表明,合成液中Ti/Si比在0.01~0.04范围内,所合成的TS-1沸石膜均具备典型MFI型拓扑结构。但当Ti/Si比>0.02时,随着Ti/Si比升高,TS-1沸石膜表面沸石颗粒排列变得杂乱,且TS-1沸石沉积量逐渐减少,沸石晶间缺陷增多,丙烯渗透速率增大。而且,当Ti/Si比=0.03、0.04时,由于所合成的TS-1沸石膜中存在大量非骨架钛,导致在丙烯环氧化反应中PO选择性和PO生成速率明显降低。当Ti/Si比为0.02时,合成的TS-1沸石膜骨架钛含量最高,其催化性能最佳,H2O_2转化率、PO选择性和生成速率分别为12.43%、95.80%和15.78 mmol/(h·g)。TS-1沸石膜在丙烯环氧化反应中重复使用8次,其催化性能保持相对稳定。

Novel method for synthesis of titanium silicalite-1 (TS-1)

Titanium silicalite-1 (TS-1) was easily synthesized using inorganic silicon and titanium source, tetrapropylammonium bromide (TPABr) or TPAOH as templating molecule, NH3H2O, HDA or TEAOH etc. as base sources. In this system, TPA+ cations (come from TPABr or TPAOH) served as templating agents to direct the MFI structure. NH3H2O, TEAOH or HDA etc. provides the alkalinity necessary for crystallization. X-ray diffraction, UV-Vis, IR spectroscopies, SEM, 29Si MAS NMR showed that the zeolites obtained possessed all the structural characteristics of TS-1, and titanium atoms were introduced into the framework in TS-1. This material was proved to have high crystallinity and high catalytic activity to allyl chloride epoxidation and propylene epoxidation. All the samples synthesized had similar catalytic properties with a standard TS-1 through compared inorganic reactant system with organic synthesis system using propylene epoxidation. The effects of silicon source and TPABr/SiO2 ratio were discussed.

多孔钛片上S-1膜的原位合成、表征及应用

用水热法在多孔钛片上原位合成沸石分子筛Ｓｉｌｉｃａｌｉｔｅ（Ｓ－１）膜。系统地考察了硅溶胶浓度、溶液ｐＨ值、晶化时间和晶化温度对成膜的影响；结合样品的ＸＲＤ和ＳＥＭ图谱，确定了最佳的制备条件。将制得的Ｓ－１膜用于乙醇水溶液渗透汽化，测定了醇／水分离的渗透通量和分离因子。结果表明，Ｓ－１膜对乙醇水溶液有良好的浓缩作用。

钛硅分子筛膜的合成及其催化性能的研究

采用水热法在堇青石蜂窝陶瓷载体上原位合成了钛硅分子筛膜。用XRD、SEM等表征方法对所合成的钛硅分子筛膜的物理化学性能进行了表征。SEM结果表明钛硅分子筛可在堇青石蜂窝载体的表面上牢固均匀地生长 ,平均厚度为 10 μm。XRD中出现了典型的MFI结构的特征峰 ,证实了TS 1原位生长于堇青石表面。以丙烯环氧化为探针反应 ,评价所合成样品的催化性能 ,并考察了n(SiO2 ) /n(TiO2 )、n(H2 O) /n(SiO2 )及添加吐温 4 0对钛硅分子筛膜厚度及催化性能的影响。结果表明膜厚与催化性能不成正比关系 ,当n(SiO2 ) /n(TiO2 )为 35、n(H2 O) /n(SiO2 )为 5 0 ,所得分子筛膜平均厚度为 14 μm时 ,过氧化氢的转化率达 31 5 % ,环氧丙烷的选择性达10 0 % ;与不加吐温 4 0的催化剂膜相比 ,吐温 4 0的添加使单位膜厚的过氧化氢转化率升高约 2 %。环氧丙烷的选择性仍保持 10 0 %。吐温 4 0有助于降低模板剂的用量 。