MCM-41

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

Facile synthesis of mesoporous composite Fe/Al2O3–MCM-41: an efficient adsorbent/catalyst for swift removal of methylene blue and mixed dyes

Abstract: In situ incorporation of mesoporous Al2O3 (meso-Al2O3) into the MCM-41 extraframework without blocking the pores generates an ordered, long range and high surface area mesoporous support Al2O3–MCM-41 (AM). The mesoporous support surprisingly shows high surface area as compared to pristine MCM-41. The incorporation of meso-Al2O3 into the extraframework of MCM-41 through the silanol group is evidenced by FTIR, 27Al MAS NMR and 29Si MAS NMR spectroscopy. The result shows that Si/Al ratio 10 (AM 10) possesses improved textural properties as compared to AM 50 and AM 90. Iron is incorporated onto the surface of AM 10 in order to modify the surface property of AM 10, forming composite Fe/Al2O3–MCM-41 (Fe/AM 10). Characterization by small angle X-ray diffraction (SXRD), transmission electron microscopy (TEM), and N2 adsorption–desorption measurements reveals that the mesoporous support and iron incorporated support possess large BET surface area (207–1244 m2 g−1), narrow pore size (2.4–2.7 nm) and high pore volume (0.370–2.37 cm3 g−1). Among them, AM 10 shows highest surface area (1244 m2 g−1), narrow pore size (2.7 nm) and pore volume (2.37 cm3 g−1). The incorporation effect of both meso-Al2O3 and iron in the formation of Fe/AM 10 has been well established by 27Al MAS NMR spectroscopy. X-Ray photoelectron spectroscopy study confirms the 2+ state of iron in Fe/AM 10 and also establishes the incorporation of meso-Al2O3 and iron. Among the prepared mesoporous supports and different wt% of iron incorporated supports, it is seen that 5 Fe/AM 10 (‘5’ denotes the wt% of iron) has high adsorption as well as photo-Fenton degradation activity for MB. Moreover, 5 Fe/AM 10 is not merely a good adsorbent but also an efficient catalyst in the adsorption and photo-Fenton degradation (100%) of MB in 15 and 5 minutes, respectively. Furthermore, in the case of mixed cationic and anionic dyes (uniform mixture of methylene blue and methyl orange), MO adsorption and degradation (by photo-Fenton process) occur appreciably on the surface of MB through cationic–anionic interaction of MB and MO.

High catalytic activity for formaldehyde oxidation of AgCo/APTES@MCM-41 prepared by two steps method

Abstract: We reported here a novel synthesis procedure to prepare a highly active bimetallic AgCo/APTES@MCM-41 catalyst. Complete oxidation of formaldehyde was achieved at temperature as low as 90 °C over the bimetallic catalysts with Ag/Co = 3/1 (mass ratio). N2 isotherms, small-angle XRD results suggested that both Ag and Co species were well dispersed on the support, and the pore structure of the support was not destroyed after introducing the active metal. The formation of the strong metal–metal interaction (SMMI) between Ag and Co in the bimetallic catalysts due to the electron transfer between each other resulted in the high Co3+/Co2+ ratio and good low-temperature reducibility. And more surface active oxygen species (Osurf) formed on the surface of the bimetallic catalysts. All these factors gave rise to the high formaldehyde catalytic oxidation activity in AgCo bimetallic catalysts. The possible structure changes of bimetallic catalysts and the reaction path for the complete oxidation of formaldehyde over AgCo bimetallic catalyst was also proposed.

Incorporation of Differently Substituted Phthalocyanines into the Mesoporous Molecular Sieve Si-MCM-41

Abstract: Substituted phthalocyanine Zn complexes exhibiting negative, positive or no charge are incorporated in the mesopores of Si-MCM-41 materials during hydrothermal synthesis in the presence of cetyltrimethylammonium chloride. The nature of the intermolecular interaction between the surfactant micelle and the capped chromophores determines (i) the resistance of the dye towards hydrolytic degradation during the synthesis and (ii) its stability of anchoring towards extraction with ethanol in the composite material. Loadings up to 2 × 10−5 mol/g molecular sieve are achieved, corresponding to an average distance between the encapsulated dye molecules between 2 and 3 nm. The UV-vis spectra reveal the non-aggregated state of the chromophores, pointing to a uniform distribution and a perfect separation by the surfactant molecules.