MCM-41

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

Amino acid-based ionic liquid immobilized on α-Fe2O3-MCM-41: An efficient magnetic nanocatalyst and recyclable reaction media for the synthesis of quinazolin-4(3H)-one derivatives

Abstract: For the first time, we report the synthesis and the application of magnetic nanocatalyst (α-Fe 2 O 3 )-MCM-41- l -prolinium nitrate which was characterized by XRD, TEM, IR, X-ray energy diffraction (XED) spectra and nitrogen physisorption measurements. l -prolinium nitrate (fully green amino acid-based ionic liquid) inside the mesochannels of (α-Fe 2 O 3 )-MCM-41 lead to prepare a new solid catalyst which was used as an efficient heterogeneous catalyst for the one-pot oxidative cyclization straight synthesis of quinazolin-4(3H)-one derivatives from isatoic anhydride, aldehyde or alkyl halide and primary amines under mild reaction conditions without using any oxidant with good to excellent yields. Moreover, it was proven that in these reactions, the use of such a hybrid material as a catalyst plays the role of rendering the reactions while neither the (α-Fe 2 O 3 )-MCM-41 nor the l -prolinium nitrate were not able to promote this reaction in the desired pathway toward the above mentioned product. The characteristic features of this catalyst are attributed to both acidic and oxidative behavior of the catalyst.

Characterization of tungstophosphoric acid supported on MCM-41 mesoporous silica using n-hexane cracking, benzene adsorption, and X-ray diffraction

Abstract: MCM-41 with all-silica composition was synthesized with unit cell parameters a = b =60 A. The material was characterized by X-ray powder diffraction and benzene adsorption. Combinations of unit cell parameter, benzene adsorption and crystal density determination have given values for the pore diameter and wall thickness in the ab -plane of the unit cell. The unit cell size shrank upon impregnation of the material with tungstophosphoric acid. The catalytic activity of tungstophosphoric acid (HPW) supported on the all-silica mesoporous MCM-41 material has been evaluated for the cracking of n -hexane. The catalyst showed a very high activity of n -hexane cracking at a temperature as low as 200°C, at very low space velocity. However, the catalyst deactivated rapidly due to coke deposition on the acid sites. At higher temperature the activity declined, most likely because of the heteropoly-acid thermal instability. Both X-ray powder diffraction and infra-red spectroscopy have shown evidence for the heteropoly-acid instability starting at 300°C. The type of the solvent used in the impregnation affected the dispersion of HPW on the MCM-41 material as indicated by benzene adsorption measurement, but it did not influence the catalytic performance for n -hexane cracking. In the case of aqueous solution, the benzene adsorption was lower than that of the parent MCM-41 material. The reduced adsorption capacity was probably due to the presence of the HPW at the pore mouth of the cylindrical channels, causing narrowing and blocking of some sections of the channels. Moreover, the adsorption isotherm showed a micropore characteristic supporting the pore narrowing proposal. In the case of using methanol solvent for the impregnation, the full adsorption capacity was retained, indicating a much higher dispersion of the HPW throughout the channels of the MCM-41 material. The benzene adsorption isotherm also showed the characteristic of mesoporosity and the adsorption capacity was not appreciably reduced. Characterization of the spent catalyst after n -hexane cracking test showed additional reduction in the benzene adsorption capacity for the aqueous impregnated catalyst. Again the methanol-impregnated catalyst had almost a full adsorption capacity.

Characterization and catalytic performance of mesoporous molecular sieves Al-MCM-41 materials

Abstract: Mesoporous Al-MCM-41 materials of different Si/Al ratios have been synthesized and characterized by X-ray powder diffraction, 27Al and 29Si MAS NMR, differential thermogravimetric analysis, N2 adsorption measurements, FT-IR and catalytic cracking of alkanes. The experimental results show that the incorporation of aluminium into the framework of MCM-41 has a great effect on the degree of long-distance order, the surface acidities and the mesoporous structures of the materials. With increase of the aluminium content, the amounts of tetrahedral framework aluminium and the acid sites on the samples increase, but the acid strength decreases. Al-MCM-41 materials exhibit high activity for n-C160 cracking and good selectivity for producing low carbon alkylenes, particularly for i-C4=.

Adsorption of Copper(II) on NH2-MCM-41 and Its Application for Epoxidation of Styrene

Abstract: Amine functionalized MCM-41 (NH2-MCM-41) with varying amine amount (6.4, 10.2, 12.8, and 20 wt %) was prepared by the cocondensation method using cetyltrimethylammonium bromide (CTAB) as structure-directing agent (SDA), 3-aminopropyltriethoxysilane (APTES), and tetraethylorthosilicate (TEOS). The characterizations of the synthesized samples were performed by X-ray diffraction, scanning electron microscopy, UV–vis diffuse reflectance spectroscopy, and Fourier transform infrared spectral studies. The results revealed that the ordered hexagonal structure of MCM-41 was well retained after the amine functionalization irrespective of the amount of amine loading. Adsorption of Cu(II) from the aqueous state with varying parameters such as concentration, temperature, and pH was performed over as-synthesized and surfactant-removed NH2-MCM-41. Atomic adsorption spectroscopy investigations reported a higher percentage of adsorption in the case of as-synthesized NH2-MCM-41 compared to surfactant-removed samples. The e...