MCM-41 mesoporous materials

The synthetic procedure for preparing the MCM-41 mesoporous materials is based on the delayed-neutralization process reported in our previous paper.[l 1] The silica source is sodium... 

Acidity of niobium containing MCM-41 mesoporous materials, as reported by Ziolek et. al [15], are sufficient to provide the relatively mild acidic sites necessary to cleave the epoxy ring leading to diols. The a-pinene conversions and H,02 selectivities were always higher with MCM-48 when compared with MCM-41 molecular sieves. This is probably due to the... 

Again in the same research group,1441 it has been shown that over Al-containing MCM-41 mesoporous materials with acidity always lower than that of zeolites, the glycosylation of D-glucose and ra-butanol proceeded at reaction rates not very far... 

The main difference between the synthesis of MCM-41 mesoporous material and traditional synthesis of zeolite or silica molecular sieve is the use of different templates. An individual organic molecule or metal cation is used for the traditional synthesis of silica microporous molecular sieve. For example, the typical template for ZSM-5 synthesis is tetrapropylammonium ion the crystal is formed through the condensation of silicate species around the template molecule, while for the formation of MCM-41, the typical template is the assembly of large molecules containing one hydrophobic chain with more than 10 carbons. 

Zeolite could selectively adsorb A -nitrosamines in the solution of methylene chloride or water, and the equilibrium data were fitted to Freundlich-type isotherms. Textural and acid-basic properties of zeolite determined their adsorption capacity. The extraordinary adsorption properties of NaA zeolite for iV-nitrosamines is inferred that the adsorbates inert the channel with the group -N=N-0. Larger amount of A-nitrosamines was adsorbed on ZSM-5 zeolite in water instead in methylene chloride, due to the hydrophobicity of the zeolite. Application of zeolite to remove A-nitrosamines from beer seems successful. Up to 100% of the worst carcinogenic compounds could thus be removed with 1.4 g/L of zeolite which was proven to be better adsorbent than silica or alumina. On Na 3 zeolite and MCM-41 mesoporous material A-nitrosodimethylamine decomposed above 573 K and the liberated NOx could be detected even at 773 K during the TPSR process, indicating the strong adsorption of A-nitrosamines on molecular sieves that makes zeolite become the functional materials for environmental protection. 

Cerium-containing MCM-41 mesoporous materials were synthesized using different methods. X-ray diffraction pattern, N2 adsorption and different spectroscopic analyses of the samples reveal that organized mesoporous MCM-41 materials were prepared. The presence of Ce is confirmed by EDX analysis. High BET surface area (494-1415 m g ) and typical XRD pattern of MCM-41 type hexagonal structure of these materials indicate the presence of hexagonal mesopores in the samples. The presence of a strong absorption centered at ca. 290 nm and an absence of ca. 400 nm absorption in the UV-Vis spectra, indicate the presence of tetra coordinated cerium in the Ce-MCM-41 samples. 

P-12 - Selective catalytic reduction of NO, by NH3 over Mn supported MCM-41 mesoporous materials... 

In 1992, Kresge and coworkers at Mobil invented the so-called MCM-41 mesoporous materials that have a hexagonal arrangement of monosized mesopores with pore size adjustable from 1.5 nm to 10 nm (Kresge et al., 1992). 

Guo, H., He, N., Ge, S., Yang, D., Zhang, J. MCM-41 mesoporous material modified carbon paste electrode for the determination of cardiac troponin I by anodic stripping voltammetry. Talanta 68, 61-66 (2005)... 

Wiench, J.W., Avadhut, Y.S., Maity, N. et al. 2007a. Characterization of covalent linkages in organically functionalized MCM-41 mesoporous materials by solid-state NMR and theoretical calculations. J. Phys. C/iem.S 111 3877-3885. 

Fig. 2. Electron micrograph of MCM-41 mesoporous material. Courtesy of B. Tesche, Max-Planck-Institut fur Kohleforschung, Mulheim, Germany.

FIGURE 7 Powder X-r diffraction pattern of MCM-41 mesoporous material. The peaks are indexed according to hexagonal (space group p6m) geometry. 

The acidity of a series of MCM-41 mesoporous materials has been investigated by microcalorimetry using ammonia adsorption at 423 K [287], giving rise to the following acid strength sequence H-[AlSi]-MCM-41 > [AlSi]-MCM-41 > [FeSi]-MCM-41 > [LaSi]-MCM-41. 

A1]-MCM-41 Mesoporous material with hexagonal arrangement of the uniform meso-pores (cf. Voliune 1, Chapter 4 of this series) containing aluminum in the pore walls... 

Fe] -MCM-41 Mesoporous material with hexagonal arrangement of the uniform meso-... 

Alkylation Reactions of Pyrazole Matos et al. proposed for the first time (Cs)Al-SBA-15 and DEAPTS/ MCM-41 mesoporous materials (where DEAPTS is diethylamino propyl) as efficient basic catalysts in the alkylation of pyrazole and diethyl iminodiacetate with various reactive alkyl bromides under conventional thermal activation (Scheme 21) [92]. The alkylation of pyrazole catalyzed by both (Cs)Al-SBA-15 and DEAPTS/MCM-41 catalysts in the presence of a solvent (acetonitrile or dimethylformamide (DMF)) afforded selectively N-alkylpyrazole 30 with high... 

Toni, C., Lesci, I. G., Fabbri, D. Analytical study on the pyrolytic behavior of cellulose in the presence of MCM-41 mesoporous materials. J Anal Appl Pyrolysis 2009,85,192-196. 

Wangeheng, Z., Guanzhong, L., Yanglong, G., Yun, G. Yunsong, W. (2008). Synthesis of Ln-doped MCM-41 mesoporous materials and their eatalytie performanee in oxidation of styrene. J. Rare Earths, 26, 59-65. 

Chen, L.Y., Jaenicke, S., and Chuah, G.K. (1997). Thermal and hydrothermal stability of framework-substituted MCM-41 mesoporous materials. Micropor Mater. 12 (4-6), 323-330. 

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