One-pot synthesis of core–shell silica–aluminosilicate composites: Effect of pH and chitosan addition

Infiltrate Mesoporous Silica-Aluminosilicate Structure Improves Hydrogen Production via Methane Decomposition over a Nickel-Based Catalyst

“…It could be explained that the first peak belonged to the main matrix mesoporous silica controlled by the CTAC template, while the peak at ∼3.9 nm should belong to the infiltrated aluminosilicate inside the silica matrix. 23 Ni/SAS(x) and Ni/MCM-41 catalysts were also those of the type IV isotherm with the H4 hysteresis loop, indicating the same mesoporous structure as the SAS(x) and MCM-41 support itself (Figure 2A). The pore sizes of Ni/SAS(x) and Ni/MCM-41 catalysts were not appreciably changed from those of their corresponding SAS(x) supports; however, the peak intensities of Ni/SAS(x) and Ni/MCM-41 catalysts were lower than those of the corresponding SAS(x) and MCM-41 supports (Figure 2B).…”

“…The formation of the infiltrate mesoporous silica-aluminosilicate composites of the SAS­( x ) support with different Si/Al ratios was confirmed by 27 Al MAS NMR spectra with the results shown in Figure . All SAS­( x ) supports exhibited two signals in common, namely chemical shifts at 1.3 and 56.4 ppm, indicating a mesoporous framework of octahedral (AlO 6 )- and tetrahedral (AlO 4 )-coordinated aluminum, − respectively. The ratio of tetrahedral to octahedral peaks on the SAS(50) support was more than those obtained for SAS(25) and SAS(100) supports as can be seen in the results shown in Table S1.…”

“…In order to overcome this drawback, a modified mesoporous silica-aluminosilicate structure is of interest for use as a support in the methane decomposition reaction because mesoporous silica-aluminosilicate provides a high surface area and its pore characteristics and diameters can be effectively controlled. 23 Moreover, its structure and acidity facilitate the reaction on the surface. The presence of a mesoporous structure improves the metal dispersion and the diffusion rates of the reactant and product gases during the reaction, resulting in the enhancement of catalyst performance in terms of activity and stability.…”

“…The zeolite materials such as ZSM-5, zeolite Y, and zeolite A have one kind of a remarkable catalyst support due to their well-defined pore distributions, unique catalytic structures, and high surface areas. , The surface acidity of the support is known to affect the metal–support interaction, metal dispersion, and reduction behavior of a metal catalyst. , However, the drawback of the Ni-supported zeolite catalyst in the methane decomposition reaction is the micropore structure (pore size lower than 2 nm) of the zeolite, resulting in the easy agglomeration of active nickel and lower metal dispersion on the support itself. In order to overcome this drawback, a modified mesoporous silica-aluminosilicate structure is of interest for use as a support in the methane decomposition reaction because mesoporous silica-aluminosilicate provides a high surface area and its pore characteristics and diameters can be effectively controlled . Moreover, its structure and acidity facilitate the reaction on the surface.…”

Molecular Structures of Al/Si and Fe/Si Coprecipitates and the Implication for Selenite Removal

“…However, the related mechanic mechanisms, especially at molecular scale, could only be determined using spectroscopic methods. For example, the interaction between Al(III) and SiO 2 was classified as adsorption, surface-enhanced precipitation, and aluminosilicate precipitation according to the results of nuclear magnetic resonance (NMR) spectroscopy 17 18 . The Fourier-transform infrared spectrometer (FT-IR) was employed to determine the elemental binding between Fe and SiO 2 , and the results showed a replacement of Si by Fe on the Fe/Si coprecipitates 19 .…”