Structural characterization of alkyl bonded MCM-41 silica materials prepared by supercritical fluid approach

Yasmin, Tahira; Müller, Klaus

doi:10.1016/j.micromeso.2015.01.035

Cited by 7 publications

(8 citation statements)

References 53 publications

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“…The adsorption bands noticed at 1224 and 1076 cm -1 correspond to external and internal asymmetric stretching vibrations of Si-O-Si bonds, respectively, and the band at 798 cm Other bands around 462 and 961 cm -1 are attributed to tetrahedral bending of Si-O bonds and stretching vibrations of the Si-OH bonds, respectively 17,26,35 . Some authors suggest that the band around 961 cm -1 also correspond to the incorporation of heteroatoms into the framework of the mesoporous silica materials, Si-O-M + (where M = Al) 17,38 .…”

Section: Resultsmentioning

confidence: 99%

“…The 29 Si MAS-NMR resonance of the MCM-41 has two peaks, one intense at -100 ppm due to Q3 structural units, Si[(OSi) 3 (OH)], and another at -91 ppm related to Q2 structural units, Si[(OSi) 2 (OH) 2 ]. Furthermore, it was also observed a shoulder at -110 ppm which is found only on purely siliceous structures, being attributed to Q4 structural units, Si[(OSi) 4 ] 26,27 . Similarly, the 29 Si MAS-NMR spectra of solids Al-MCM-41(50) and Al-MCM-41 (15) showed two peaks, one intense at -99 ppm due to the presence of Si species, finding in their neighborhoods an aluminum atom, Si[(OSi) 3 (OAl)], and other with low intensity at -90 ppm due to the Si species with two or three aluminum neighboring atoms, Si[(OSi) 2 (OAl) 2 ] and Si[(OSi)(OAl) 3 ], respectively 18,22,[28][29][30] .…”

Section: Resultsmentioning

confidence: 99%

“…The reduced acidity of the pure siliceous MCM-41 may be attributed to the presence of Si-OH groups in its surface from adsorbed water molecules 26,[36][37][38] . However, when the Si/Al ratio was varied from MCM-41(50) to MCM-41(15), there was not a significant increase in the total acidity in this last sample.…”

Section: Resultsmentioning

confidence: 99%

“…In Figure 5 is shown the FT-IR samples profiles as-synthesized (not calcined) and after calcined in synthetic air stream at 813 K, corresponding to siliceous pure MCM-41 and Al-containing samples like Al-MCM-41(50) and Al-MCM-41 (15). In as-synthesized samples were observed bands at 2921, 2852, 1477 and 719 cm -1 corresponding to the deformation vibration of the C-H bonds present in the CH 2 and CH 3 groups of the surfactant molecules, CTAB, used as pore template agent 25,26,35,39 . After calcination, those bands disappear completely, indicating that the CTAB molecules were completely removed from the pores of the molecular sieves.…”

Section: Resultsmentioning

confidence: 99%

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Influence of Aluminum Addition in the Framework of MCM-41 Mesoporous Molecular Sieve Synthesized by Non-Hydrothermal Method in an Alkali-Free System

et al. 2017

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Purely siliceous MCM-41 and Al-containing MCM-41 (Al-MCM-41) mesoporous materials were synthesized by non-hydrothermal method in alkali-free ions medium at room temperature and short reaction times. Under these synthesis conditions, it was also investigated the influence of Al incorporation in the crystal structure of MCM-41. The solids were characterized by ICP-OES, AAS, N 2 adsorption at 77 K, XRD, TEM, NH 3 -TPD, 27 Al and 29 Si-MAS-NMR, FT-IR and TGA. The resulting mesoporous materials showed a well-defined hexagonally ordered pore geometry maintaining a uniform and unimodal pore size distribution with high specific surface areas (1000-1400 m 2 g -1 ). The Al +3 ions were introduced successfully in the structure of the purely siliceous MCM-41 expanding the unit cell parameter and forming four-coordinated Al species, and in a less extent, forming six-coordinated Al species. In addition, the surface acidity of the MCM-41 increased with Al loading. Contrary, the presence of Al in the MCM-41 mesoporous structure resulted in a decrease of the crystallinity and specific surface area possibly due to the presence of Al species in highly distorted tetrahedral structures and Al extra-framework or amorphous alumina occluded in the pores. The MCM-41 type mesoporous materials obtained in this work show similar characteristics of those synthesized by conventional hydrothermal methods.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Influence of Aluminum Addition in the Framework of MCM-41 Mesoporous Molecular Sieve Synthesized by Non-Hydrothermal Method in an Alkali-Free System

et al. 2017

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“…Yasmin and Muller have applied supercritical fluid approach to prepare alkyl bonded mesoporous MCM-41 silica materials with higher surface coverages. 352 The degree of bonding and cross-linking of the alkylsilanes was determined by 29 Si NMR spectroscopy, and the application of FT-IR and 13 C NMR spectroscopy revealed the conformational behaviour and mobility of the bonded alky chains.…”

Section: Fig 32 2d 13 C-1 H Hetcor Nmr Spectra Of As Synthesized (Rimentioning

confidence: 99%

Combined solid-state NMR, FT-IR and computational studies on layered and porous materials

et al. 2018

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Understanding the structure-property relationship of solids is of utmost relevance for efficient chemical processes and technological applications in industries. This contribution reviews the concept of coupling three well-known characterization techniques (solid-state NMR, FT-IR and computational methods) for the study of solid state materials which possess 2D and 3D architectures and discusses the way it will benefit the scientific communities. It highlights the most fundamental and applied aspects of the proactive combined approach strategies to gather information at a molecular level. The integrated approach involving multiple spectroscopic and computational methods allows achieving an in-depth understanding of the surface, interfacial and confined space processes that are beneficial for the establishment of structure-property relationships. The role of ssNMR/FT-IR spectroscopic properties of probe molecules in monitoring the strength and distribution of catalytic active sites and their accessibility at the porous/layered surface is discussed. Both experimental and theoretical aspects will be considered by reporting relevant examples. This review also identifies and discusses the progress, challenges and future prospects in the field of synthesis and applications of layered and porous solids.

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Robust Optimization and Characterization of MCM‐41 Nanoparticle Synthesis using Modified Sol‐Gel Method

Shende

Chaudhari

2023

ChemistrySelect

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Mesoporous silica nanoparticles (MSN) for drug delivery application requires great expertise to synthesize small sized monodisperse particles. We aimed at synthesizing and optimizing MCM‐41 particles with the modified Stober's method by adjusting factors such as concentrations of cetyltrimethylammonium bromide (CTAB), sodium hydroxide (NaOH) and water (H2O) with respect to tetraethyl orthosilicate (TEOS), and a process parameter (stirring). We comprehended that the reactants determined the shape and size of both the particles and pores. Upon extensive characterization we report the synthesis of spherical particles of ∼70 nm size in a monodisperse population; the structures had hexagonal ordered pores of diameter 3.071 nm and volume 3.124 cm3/g; the total surface area of 3410.648 m2/g of the particles was covered with silanol groups that aid in functionalization; the particles exhibited great thermal stability. Thus, the extensive optimization fabricated robust MCM‐41 particles fit for drug delivery application.

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Structural characterization of alkyl bonded MCM-41 silica materials prepared by supercritical fluid approach

Cited by 7 publications

References 53 publications

Influence of Aluminum Addition in the Framework of MCM-41 Mesoporous Molecular Sieve Synthesized by Non-Hydrothermal Method in an Alkali-Free System

Influence of Aluminum Addition in the Framework of MCM-41 Mesoporous Molecular Sieve Synthesized by Non-Hydrothermal Method in an Alkali-Free System

Combined solid-state NMR, FT-IR and computational studies on layered and porous materials

Robust Optimization and Characterization of MCM‐41 Nanoparticle Synthesis using Modified Sol‐Gel Method

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