无机钛硅原料体系合成TS-1催化丙烯环氧化反应

研究了无机钛硅原料体系合成的ＴＳ－１催化丙烯环氧化的反应,并与经典法、修正法制得样品的催化性能进行了比较。考察了搅拌、Ｎａ２ＣＯ３加入量、反应时间、反应温度、双氧水加量、催化剂量及溶剂等对丙烯环氧化反应的转化率、选择性等的影响,并初步探讨了无机钛硅原料合成的ＴＳ－１的再生性能。结果表明,对于丙烯环氧化反应,无机钛硅原料合成ＴＳ－１样品与经典法和修正法制取样品的催化性能相当;反应条件对丙烯环氧化反应     

Ti-MWW催化烯丙基氯环氧化高效合成环氧氯丙烷

 研究了具有MWW结构的新一代钛硅分子筛Ti-MWW催化剂对烯丙基氯液相环氧化高效合成环氧氯丙烷的催化性能. 结果表明, Ti-MWW的催化活性以及产物选择性均优于传统的钛硅分子筛TS-1. 对于Ti-MWW,合适的溶剂为非质子性溶剂丙酮和乙腈,在该溶剂中环氧化物不易发生溶剂化开环反应; 而对于TS-1,合适的溶剂是质子性溶剂甲醇,但甲醇可导致醇醚副产物的生成. 在Ti-MWW催化剂上烯丙基氯的转化率和环氧氯丙烷的选择性都能达到99%以上.     

天然丝光沸石多步脱铝-钛化制备钛硅分子筛

以优选的天然丝光沸石为原料, 采用多步脱铝-钛化法合成钛硅分子筛, 利用 X 射线粉末衍射、紫外-可见光谱、电感耦合等离子体原子发射光谱、N2 吸附-脱附法以及氨程序升温脱附等手段对其进行了表征, 并考察了它在苯乙烯氧化反应中的催化性能. 结果表明, 该方法可成功地将 Ti 同晶取代到天然丝光沸石的骨架中, 其 Si/Ti 达到 79, 且能稳定地保持天然丝光沸石的结构. 该钛硅分子筛在以 H2O2 水溶液为氧化剂的苯乙烯氧化反应中表现有良好的催化活性, 是商业 TS-1 催化剂的 75%, 具有一定的应用前景.     

具有 MWW 结构钛硅分子筛的研究进展

 综述了具有 MWW 结构钛硅分子筛的制备方法、孔道和晶体结构的调变和修饰以及催化应用三个方面的研究进展. 与 TS-1 相比, 具有 MWW 结构钛硅分子筛的制备方法多种多样; 其孔道结构可塑性强, 通过采用层间剥离、柱撑以及分子水平硅烷化插硅扩孔技术, 可以增大和暴露孔道和外表面, 满足不同选择氧化反应的要求. 由于 MWW 结构钛硅分子筛拥有复杂而独特的孔道结构, 所以在小分子 (如直链烯烃等) 的环氧化反应, 和大分子 (环状烯烃, 二苯并噻吩等) 氧化反应中都表现出优异的催化性能. 此外, 该钛硅分子筛表现出与 TS-1 完全不同的溶剂效应, 用于烯丙基氯液相环氧化与酮类氨氧化反应主产物选择性更高.     

钛－硅沸石的结构表征及其催化性能

ＸＲＤ，ＩＲ，２９ＳｉＭＡＳＮＭＲ，ＵＶ－ＶＩＳ及ＸＰＳ能谱表征证实钛原子进入了钛－硅五元环沸石的骨架晶格位（不含铝）．ＴＧ－ＤＴＡ结果表明，钛原子进入沸石骨架导致沸石骨架的热稳定性提高，超过１４７３Ｋ．氯丙烯与Ｈ２Ｏ２（３０％）的环氧化反应结果表明钛－硅沸石具有优异的氧化性能，这也从另一个侧面证实了钛原子位于沸石骨架晶格位．     

Optical properties and local structure of Eu-doped synthetic analogue of the microporous titanosilicate mineral sitinakite

The synthetic analogue of the microporous titanosilicate mineral sitinakite has been hydrothermally synthesized and used as a host in the preparation of a new photoluminescent material. The inclusion of Eu³⁺ in the pores of the sitinakite doubles the unit cell volume and changes the symmetry of the initial sodium phase. The Eu³⁺-doped material displays a stable room temperature emission ascribed to the Eu³⁺ intra-4f^{6 5}D₀→⁷F₀₋₄ transitions, with a maximum external quantum yield of 6%. The observation of two components for the non-degenerated ⁵D₀→⁷F₀ transition, the local field splitting of the ⁵D₀→⁷F₁₋₂ transitions, and the ⁵D₀ emission decay curves point out the presence of two optically active Eu³⁺ sites. Possible structural distribution of the detected Eu³⁺ cations is discussed.     

季铵盐功能化的钛硅分子筛催化丙烯氧化酯化合成碳酸丙烯酯

将有机卤素季铵盐以硅烷化键合方式嫁接到钛硅分子筛上,制备了兼备催化氧化烯烃合成环氧化物和环氧化物碳酸酯化反应的新型双功能催化剂,考察了其在丙烯、过氧化氢和二氧化碳一步合成碳酸丙烯酯的催化性能.研究表明,具有大外表面积的层剥离的钛硅分子筛是一种嫁接季铵盐合适的载体,丙基三丁基卤化铵是酯化催化性能优良的功能化基团,两者的偶合使一步法催化丙烯环氧化酯化合成碳酸丙烯酯的收率达48%.该催化剂具有较好的稳定性和重复使用性能.     

超疏水性层状钛硅微球材料的制备与催化应用

以气溶胶辅助自组装的方法合成了超疏水性的有机无机杂化层状钛硅微球材料(micro sphere layered organotitanosilicate,ms-LOTS);利用扫描电子显微镜(SEM)观察材料的微球形貌,利用X射线粉末衍射(XRD)和红外光谱(FT-IR)表征材料的结构信息,并考察其在环己烯环氧化反应中的催化活性。研究发现,前驱体浓度和自组装温度是影响材料的微球形貌的关键因素,控制一定的合成条件,可以制备颗粒分布均匀、粒径为2~4μm的超疏水性层状钛硅微球材料;该材料在室温下环己烯环氧化反应中表现出良好的催化活性。     

Titanosilicate beads with hierarchical porosity: synthesis and application as epoxidation catalysts

Porous titanosilicate beads with a diameter of 0.5-1.5 mm (TiSil-HPB-60) were synthesized from a preformed titanosilicate solution with a porous anion-exchange resin as template. The bead format of this material enables its straightforward separation from the reaction mixture in its application as a liquid-phase heterogeneous catalyst. The material displays hierarchical porosity (micro/mesopores) and incipient TS-1 structure building units. The titanium species are predominantly located in tetrahedral framework positions. TiSil-HPB-60 is a highly active catalyst for the epoxidation of cyclohexene with t-butyl hydroperoxide (TBHP) and aqueous H(2)O(2). With both oxidants, TiSil-HPB-60 gave higher epoxide yields than Ti-MCM-41 and TS-1. The improved catalytic performance of TiSil-HPB-60 is mainly ascribed to the large mesopores favoring the diffusion of reagents and products to and from the titanium active sites. The epoxide yield and selectivity could be further improved by silylation of the titanosilicate beads. Importantly, TiSil-HPB-60 is a stable catalyst immune to titanium leaching, and can be easily recovered and reused in successive catalytic cycles without significant loss of activity. Moreover, TiSil-HPB-60 is active and selective in the epoxidation of a wide range of bulky alkenes.     

Hydrothermally Stable and Catalytically Active Ordered Mesoporous Materials Assembled from Preformed Zeolite Nanoclusters

Microporous zeolites are widely used commercial catalysts, but their applications are intrinsically limited by their small channel diameters. Recent progress in solving this is used to ordered mesoporous materials such as MCM-41, HMS and SBA-15. These mesoporous materials have pore diameters of 30–60 Å and exhibit catalytic properties for the catalytic conversion of bulky reactants, but unfortunately, when compared with microporous zeolites, the catalytic activity and hydrothermal stability are relatively low, which severely hinders their practical applications. The relatively low catalytic activity and hydrothermal stability can be attributed to the amorphous nature of the mesoporous walls. We review here that the assembly of preformed zeolite precursors with surfactants can synthesize a series of ordered mesoporous materials, which include (1) strongly acidic and hydrothermally stable mesoporous aluminosilicates synthesized in alkaline media; (2) strongly acidic and hydrothermally stable mesoporous aluminosilicates synthesized in strongly acidic media; (3) hydrothermally stable mesoporous titanosilicates with catalytically active titanium species in oxidations; (4) hydrothermally stable mesoporous ferrisilicates. This work would open a door for the industrial application of mesoporous materials as catalysts for large molecules.