Ce-MCM-48介孔分子筛的合成、表征和催化性能

Cerium incorporated MCM-48 molecular sieves have been hydrothermally synthesized by both a mixed template and a variable pH approach. The samples were characterized by various physicochemical methods, including X-ray diffraction, transmission electron microscopy, diffuse reflectance UV-vis spectroscopy, XRF spectroscopy, nitrogen adsorption. These results reveal that cerium is incorporated in MCM-48 in the form of well-dispersed tetra-coodinated cerium ion. Maintaining the proper concentration of cerium and adjusting the pH allows for a more ordered structure with a much higher specific surface area than that of MCM-48. Ce-MCM-48 was employed in the liquid phase oxidation of cyclohexane with aqueous H2O2. The results showed that Ce-MCM-48 is more active as a catalyst for the liquid phase oxidation of cyclohexane. The oxidation conversion catalyzed by Ce-MCM-48 is 8.3 %-14.2% higher than that catalyzed by MCM-48 and the selectivity for the main products increase by 63.4%-68.8%. Accordingly, Ce-MCM-48 has been shown to have important potential applications.     

YOx -MCM-41介孔分子筛的合成与表征

以十六烷基三甲基溴化铵为模板剂,偏硅酸钠为硅源,硝酸钇为钇源,用水热法合成了YOx-MCM-41介孔分子筛,经X射线粉末衍射法,FT-IR,热重分析,紫外漫反射法及N2吸附-脱附法表征。结果表明,该分子筛具有热稳定性好、比表面积大、孔道均一等典型的MCM-41介孔分子筛的特征。     

高铜含量中孔Cu-Si二元氧化物的合成和表征

采用CTAB(十六烷基三甲基溴化铵)为模板剂,Na₂SiO₃·10H₂O为硅源,Cu(NH₃)₄(NO₃)₂为铜源,在常温下成功地合成出含铜质量分数高达26%,具有中孔结构的硅基氧化铜复合材料.较系统地研究了反应时间、温度、pH值和铜掺入量等对产物性能的影响.用XRD,HRTEM,FTIR,BET,TG-DTA,ICP和XPS等手段对合成产物的结构进行了表征.     

介孔材料在微PDMS芯片固定化酶中的应用

酶解是蛋白质分析的重要前处理方法.微流控芯片具有样品耗样量小,可以实现样品的预处理、分离、富集、鉴定等分析过程于一体等特点.将酶固定在微流控分析芯片上,可以为蛋白质样品的分析提供一个高通量的技术平台.     

Analysis on Band Gaps of MCM-41 Type of Materials

The concept and analysis method of photonic crystals and band gaps are introduced into one-dimenslonal (1D) ordered mesoporous materials. MCM-41 type of materials are treated theoretically as photonie crystals. The formation of band gaps is exhibited and confirmed by a calculation of transfer matrix technique. PBG was found around 9-42 nm in soft X-ray region. The photonie band-gap was predicted to be dependent on incident direction, pore size and lattice constant. The mesoporous materials with different pore sizes and different lattice constants have different band-gap widths.     

Ti-modified Mesoporous Molecular Sieves Containing both Selective Oxidation and Photocatalysis Centers

IntroductionIn recent years,titanium- containing meso-porous molecular sieves have attracted considerableattention of some scholars and scientists because oftheir remarkable catalytic properties in selectiveoxidation reactions by H2 O2 in aqueous solution asthe oxidant[1_ 3 ] .The high cost and low efficiencyof H2 O2 ,however,limits its application on an in-dustrial scale.In our previous work[4] ,we foundthat using Ti- substituted MCM- 41 as a catalystforthe hydroxylation ofbenzene with H2…     

Polarization-maintaining photonic crystal fibre

Photonic crystal fibres (PCFs) offer new possibilities of realizing highly birefringent fibres due to a higher intrinsic index contrast compared to conventional fibres. In this paper, we analyse theoretically the modal properties of a kind of polarization-maintaining PCF, namely the elliptical hole photonic crystal fibre (EHPCF) with a central small elliptical hole introduced in the core region. We demonstrate the possibility of achieving large birefringence with zero walk-off in the single-mode regime. This PCF also exhibits unusual dispersion properties. Several hundred nanometres of ultra broadband flattened dispersion near the wavelength 1.55μm is achieved in this EHPCF with a central small hole of d_c=0.4Λ.     

Eu(TTA)_3/MCM-41介孔复合体的溶胶凝胶法组装

利用溶胶 凝胶法将稀土配合物Eu(TTA) 3 组装到MCM 41介孔分子筛的孔道中 ,并初步认定客体分子Eu(TTA) 3 是以加合物形式包裹于表面活性剂胶束中。该法制得的介孔复合体Eu(TTA) 3/MCM 41,用XRD、HRTEM技术证实具有短程有序的、规整的六方介孔结构和大小分布均匀的纳米晶粒。对其光致发光和荧光寿命的研究发现 :与乙醇溶液中相比 ,Eu3 的荧光寿命没有发生改变 ,但Stokes位移却明显增大 ;复合体中 ,能量是从主体MCM 41传递到客体Eu(TTA) 3 上。     

MCM-41分子筛的合成及129Xe核磁共振的研究

ＭＣＭ４１中孔分子筛是１９９２年由Ｍｏｂｉｌ公司的科学家Ｋｒｅｓｇｅ［１］等人首次合成的,并在《自然》杂志发表。这种中孔分子筛具有六角形孔径,孔径２ｎｍ～１０ｎｍ,这种分子筛的孔径可以通过水晶模板来控制［２］。已报道的合成ＭＣＭ４１,孔径一般在２．０ｎｍ～３．５ｎｍ,使用的水晶模板一般是单一或两种阳离子季铵盐表面活性剂［３,４］。本论文通过引入第二种扩孔模板,与阳离子季铵盐协同作用,合成了孔径５．２ｎｍ（ＢＥＴ法测）的ＭＣＭ４１。通过氮气的吸脱附,测定了分子筛的比表面和孔径等性质。Ｊ．Ｆｒａｉｓｓａｒｄ…     

中孔载体上组装Ti催化活性中心的研究Ⅰ-钛配合物在中孔HMS载体上的组装

利用六角中孔硅载体（记为 HMS）上丰富的表面羟基与钛酸异丙酯、四氯化钛的交换反应,实现了钛配合物在载体上的组装。 FT-IR表征表明载体与钛化合物的键合作用会使样品出现一个新的 960cm－ 1带, 该带可归属于与钛化合物键合的 Si-OH振动带;交换温度会明显影响钛化合物与载体羟基的交换反应模式;酒石酸二乙酯（ DET）被键合后其 C=O带没有明显位移证明 DET是以其 OH与键合在载体上的钛化合物发生键合作用。在催化苯乙烯环氧化反应中,键合于载体上的钛配合物比其均相配合物的催化活性要高得多,钛源、配体和交换温度对催化氧化活性和环氧化选择性均有较大影响。