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MCM-41

About: MCM-41 is a research topic. Over the lifetime, 2355 publications have been published within this topic receiving 91416 citations.


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Journal ArticleDOI
TL;DR: In this paper, a series of hierarchically porous materials with core-shell structures have been successfully fabricated through a modified Stober method, where the interfacial growth of mesoporous silica with adjustable mesochannel orientation on the surface of ZSM-5 nanocrystal results in the formation of a coreshell structure.

68 citations

Journal ArticleDOI
TL;DR: In this paper, mesoporous Al-MCM-41 molecular sieves in four Si/Al ratios: 25, 50, 75 and 100, were synthesized under hydrothermal condition.
Abstract: Mesoporous Al-MCM-41 molecular sieves in four Si/Al ratios: 25, 50, 75 and 100, were synthesised under hydrothermal condition. They were characterized using powder X-ray diffraction (XRD), FT-IR, BET and thermogravimetric–differential thermal analysis (TGA–DTA). The XRD spectra showed that the materials were of hexagonal mesoporous structure. The FT-IR spectra revealed the order of the hydrophobic character of the catalyst materials when one compared the broad envelopes due to the O H stretching of water in the higher energy region. The acidity of the catalyst was measured by FT-IR using pyridine as the diagnostic base. The BET surface area measurements indicated the surface areas between 900 and 1000 m 2 g −1 and pore diameters around 26 A units. The catalytic activity of the materials was tested for the vapour phase esterification of acetic acid with n -butyl alcohol (NBA), isobutyl alcohol (IBA) and tertiary butyl alcohol (TBA) under autogeneous condition at 100, 150, 175 and 200 °C. NBA conversion was found to be higher than IBA and TBA. The hydrophobic properties of catalyst, alcohols and the stearic properties of alcohols were suggested to play important roles in the esterification. Al-MCM-41 (25) for NBA, Al-MCM-41 (100) for IBA and TBA was found to be more active. The mechanism was Eley–Rideal type. The reaction was also studied over commercially available heteropolyacids and zeolites (HM, Hβ, HZ and ZSM-5). Except for zeolites, other catalysts were found to have nearly identical activity to that of Al-MCM-41. Zeolites showed less activity for NBA and TBA but comparable activity to IBA. The requirement of Bronsted acid sites for the reaction was clearly established by running the reaction in the absence of catalyst. Occurrence of the reaction mainly within the pores was confirmed by running the reaction over the as-prepared catalyst that provides less conversion than the calcined material.

68 citations

Journal ArticleDOI
TL;DR: In this paper, the aminolysis of epoxides over novel solid catalysts (Bronsted acidic SBA-15 functionalized with propylsulfonic acid and Lewis-acidic Ti-MCM-41) was reported, and the acid properties of these catalysts were determined by FTIR spectroscopy and temperature-programmed desorption of pyridine and NH3, respectively.

67 citations

Journal ArticleDOI
TL;DR: In this article, a Ti-MCM-41 catalyst was synthesized by a sol-gel method and characterized by XRD, DRS, ICP and BET, and the operative reaction conditions, under which no Ti leaching was detected, were determined.
Abstract: The limonene oxidation with H 2 O 2 (“clean” oxidation) using a Ti-MCM-41 catalyst was studied. This catalyst was synthesized by a sol–gel method and characterized by XRD, DRS, ICP and BET. The operative reaction conditions, under which no Ti leaching was detected, were determined. In these conditions the catalyst has shown a high activity, and very good selectivity towards epoxides. The kinetic parameter measurements were carried assuming a heterogeneous reaction and empirical power rate law. Using the initial rate method, a first order with respect to the concentrations of catalyst, limonene and hydrogen peroxide were determined. An apparent activation energy value of 16.4 kJ/mol and a pre-exponential Arrheniuśs factor of 7.1 l 2 /g mol h were obtained.

67 citations

Journal ArticleDOI
TL;DR: In this paper, mesoporous titania-silica catalysts were prepared by hydrothermal conversion from synthesis solutions containing a zeolite structure directing agent (TPA+) and a porogen (CTA+).
Abstract: Mesoporous titania-silica catalysts were prepared by hydrothermal conversion from synthesis solutions containing a zeolite structure directing agent (TPA+) and a porogen (CTA+). Syntheses were carried out with and without addition of zeolite seeds (i.e., TS-1 and Sil-1 nanocrystals). Catalysts prepared in the presence of zeolite nanocrystal seeds have greater proportions of tetrahedrally coordinated titanium, which correlate well with the detection of zeolite SBU fragments and ring-structure by TOF-SIMS and FTIR. The incorporation of titano-silicates and zeolite structural units in the mesopore walls could explain the better activity and stability of these catalysts (Ti-MT1 and Ti-MS1) compared to the catalyst prepared by the conventional method (Ti-MCM-41). The similarity in the reactivity of catalysts prepared from TS-1 and Sil-1 nanocrystal seeds dispels the idea that the seeds are merely a source of the zeolite fragments incorporated in the pore walls but instead suggests that the seeds play an active...

67 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202334
202258
202172
202071
201993
201890