Encapsulation of fluorescein into MCM-41 mesoporous molecular sieve by a sol-gel method

MCM-41-hosted fluorescein mesophase was prepared by addition of the dye into the sol-gel mixture for the synthesis of MCM-41 mesoporous molecular sieve under microwave radiation. The as-synthesized organo-silica-surfactant material possessed hexagonal mesostructure with short-range symmetry and a uniform nanosize of about 30 nm. Furthermore, fluorescence spectrum, increase in lifetime and lack of aggregation at high concentration were discussed in terms of the effect of the host-guest interaction on these properties. (C) 2001 Published by Elsevier Science B.V.

新型无机-有机杂化中孔发光材料(phen)_2Eu/MCM-41的合成与表征

合成出了担载稀土有机配合物的无机 -有机杂化中孔发光材料 ( phen) 2 Eu/MCM-4 1 ,用 X射线衍射、红外光谱、荧光光谱和紫外 -可见漫反射光谱对所得样品进行了表征 ,并与相应的纯稀土配合物进行了比较 .结果表明 ,所得杂化材料具有典型的中孔材料 MCM-4 1的结构 ,且经组装后孔结构保持不变 ,在紫外光照射下 ,发出稀土离子的特征谱线 ,但与纯稀土配合物相比 ,其激发光谱发生蓝移 ,稀土 Eu3+ 所处的格位对称性降低 ,荧光寿命延长 .另外 ,对光谱性质进行了讨论 .

A novel catalyst for clean production of diphenols - Ferric trisacetylacetonate MCM-41

Ferric trisacetylacetonate has been deposited within the zeolite MCM-41 and the product characterized by XRD and IR. In water at pH 7 it catalyzes the oxidation of phenol by H2O2, giving 58% conversion in 1 h at 50 degrees C: products are catechol (66%), hydroquinone (27%) and benzoquinone (7%). Other oxidants and solvents are much less effective. UV-VIS spectra suggest a radical substitution mechanism, and a pollution-free process for phenol hydroxylation is now possible.

Iron(II)-8-quinolinol/MCM-41-catalyzed phenol hydroxylation and reaction mechanism

Iron(II)-8-quinolino/MCM-41 is prepared. Its catalysis is studied in phenol hydroxylation using H2O2 (30%) as oxidant. The experiment shows that Iron(II)-8-quinolinol/MCM-41 has good catalytic activity and desired stability. Based on cyclic voltammetry, ESR, and UV-visible spectra studies of iron(II)-8-quinolinol complex in liquid phase, a radical substitution mechanism is proposed and used to demonstrate the experimental facts clearly. (C) 1997 Academic Press.

八羟基喹啉铁(Ⅱ)/MCM-41对苯酚羟化的催化作用

利用ＭＣＭ－４１中孔分子筛为载体，制备了负载型八羟基喹啉铁（Ⅱ）／ＭＣＭ－４１（简记为Ｆｅ（Ⅱ）－Ｑｘ／ＭＣＭ－４１）催化剂．ＸＲＤ，ＩＲ证明八羟基喹啉铁（Ⅱ）配合物成功地负载于ＭＣＭ－４１分子筛中．考察了八羟基喹啉铁（Ⅱ）／ＭＣＭ－４１对苯酚羟化反应的催化作用，和未负载的配合物相比，苯酚的转化率、对苯二酚的选择性以及Ｈ２Ｏ２的利用率都有显著的提高．同时也探讨了温度、反应介质及介质ｐＨ值对苯酚羟化反应的影响．结果表明，随着温度的提高，苯酚的转化率增加，但温度太高，易导致副产物增多；有机溶剂不利于羟化反应的进行，水是实验条件下苯酚羟化反应的最佳反应介质；在一定程度上，ｐＨ值越低，越有利于反应活性的提高，若ｐＨ值太低，活性反而下降，ｐＨ值升高不利于苯酚羟化反应的进行．该催化剂也具有较高的稳定性.

Immobilization of the heteropoly acid (HPA) H4SiW12O40 (SiW12) on mesoporous molecular sieves (HMS and MCM-41) and their catalytic behavior

Supported catalysts, consisting of SiW12 immobilized on hexagonal mesoporous silica (HMS) and its aluminum-substituted derivative (MCM-41) with different loadings and calcination temperatures, have been prepared and characterized by X-ray diffraction, FT-IR and NH3-temperature programmed desorption. It is shown that SiW12 retains the Keggin structure on the mesoporous molecular sieves and no HPA crystal phase is developed, even at SiW12 loadings as high as 50 wt%. In the esterification of acetic acid by n-butanol, supported catalysts exhibit a higher catalytic activity and stability and held some promise of practical application. In addition, experimental results indicate that the loaded amount of SiW12 and the calcination temperatures have a significant influence on the catalytic activity, and the existence of aluminum has also an effect on the properties of supported catalysts.

Hydroxylation of phenol by iron(II)-phenanthroline(Phen)/MCM-41 zeolite

MCM-41 zeolite and Tron (II)-Phen/MCM-41 zeolite have been prepared and characterized by XRD, IR, NH3-TPD, HET and UV-Vis. The Iron( II)-Phen/MCM-41 zeolite+30% H2O2 system is capable for catalyzing hydroxylation of phenol.

Hydroxylation of phenol by iron(II)-phenanthroline(Phen) MCM-41 zeolite

MCM-41 mesoporous molecular sieve and iron(II)-Phen/MCM-41 have been prepared and characterized by XRD, IR, NH3-TPD, BET and UV-Vis. The iron(II)-Phen/MCM-41 molecular sieve + 30% H2O2 system is capable of performing hydroxylation of phenol.

铁1,10-菲咯啉/MCM-41催化苯酚羟化反应的研究

MCM-41分子筛是最近美国Mobil公司开发出的一种新材料,其孔径范围在2.0～25nm之间,具有较大的Si/Al比和大的比表面积及孔隙率,孔道大小均匀.其对弱极性的环状及芳族化合物具有较大的吸附能力.自这种新型分子筛合成以来,才开始应用于石油炼制及烯烃裂解,歧化的研究.至今还没有关于将MCM-41作为载体,用于负载金属配合物催化剂的报道.本文利用自己合成的MCM-41分子筛作为载体,制成了负载铁的1,10-菲咯啉配合物催化剂(简记FePhen/MCM-41),并将其应用于苯酚的羟化反应,发现其对苯酚的羟化反应具有较好的催化性能.1 实验部分1.1 FePhen/MCM-41的制备将参考文献[3]制得的MCM-41分子筛,取5g放入200mL0.05mol/L的[Fe(Phen)_3]Cl_2乙醇溶液中,室温搅拌24h,抽滤,所得固体用乙醇洗涤3次,以除去MCM-41分子筛表面和孔道内结合不牢的金属配合物.利用原子吸收光谱分析仪,测得负载催化体系中铁元素的含量为0.65%.1.2 MCM-41分子筛及FePhen/MCM-41的表征

The chemical nature of carbonaceous deposits and their role in methane dehydro-aromatization on Mo/MCM-22 catalysts

Various carbonaceous deposits are formed during the course of methane dehydro-aromatization (MDA) under non-oxidative conditions on Mo/MCM-22 catalysts. These carbon species were investigated by various temperature-programmed techniques such as TPH and TPCO2, combining with TPO and TGA results in order to reveal their chemical nature and determine their amounts. The TPO profiles recorded from coked Mo/MCM-22 catalysts show two temperature peaks: one at about 756 K and the other at about 876 K. The coke amounts related to these two peaks were determined on the basis of the corresponding corrected and deconvoluted TPO profiles, combining with the TGA profiles concerned.

An investigation of the roles of surface aluminum and acid sites in the zeolite MCM-22

Ammonia adsorption studies reveal that the observed Lewis acidity in the zeolite MCM-22 is derived from at least two types of framework aluminum sites (Al(F)), that is, octahedral Al(F) and three-coordinate Al(F). Comparative ammonia or trimethylphosphine (TMP) adsorption experiments with MCM-22 confirm that octahedral Al species gives rise to the signal at delta(ISO) approximate to 0 in the (27)Al NMR spectrum; this is a superposition of two NMR signals from the different Al species on the water-re constructed zeolite surface. A sharp resonance assigned to framework Al reversibly transforms on ammonia adsorption to delta(ISO) (27)Al approximate to 55 from tetrahedral Al(F), while the broad peak is assigned to nonframework aluminium which results from hydrothermal treatment. This study also demonstrates the effectiveness of (27)Al magic angle spinning (MAS) and multiple quantum (MQ) MAS NMR spectroscopy as a technique for the study of zeolite reactions.

Synthesis and characterization of manganese-modified MCM-41

Manganese-modified mesoporous MCM-41 molecular sieves were synthesized at the absence of alkaline metal ions under mild alkaline condition using cetylpyridinium bromide surfactant as a template, and characterized with X-ray diffraction, N-2 adsorption, transmission electron microscopy, electron spin resonance (ESR), and nuclear magnetic resonance (NMR) spectroscopies. The synthesized MnMCM-41 has a high pore volume of 1.30 cm(3) g(-1) with a corresponding surface area of 1510 m(2) g(-1). The ESR and Si-29 MAS NMR spectra revealed the presence of framework manganese ions in either the as-synthesized or calcined forms. (C) 2002 Elsevier Science B.V. All rights reserved.