Novel organic–inorganic mesoporous luminescent polymeric hybrid materials containing europium(III) complexes incorporated to mesoporous silica SBA-15/SBA-16 have been prepared by simple physical doping (impregnation) methods, followed by the addition polymerization reaction of the monomer 4-vinylpyridine (vpd) extending along the mesoporous channels. The precursor europium(III) complexes are synthesized by β-diketonate (β-diketonate=2-thenoyltrifluoroacetonate (tta), hexafluoroacetylacetonate (hfac), trifluoroacetylacetonate (taa)) and monomer 4-vinylpyridine (vpd) coordinated to Eu 3+ , and SBA-15/SBA-16 are obtained via a sol–gel process. After the physical doping and the polymerization reaction , the final ternary materials Eu(β-diketonate) 3 pvpd-SBA-15/Eu(β-diketonate) 3 pvpd-SBA-16 (β-diketonate=tta, hfac, taa) are received. The physical properties and espeically the photoluminescence of these hybrids are characterized, and the XRD and BET results reveal that all of these hybrid materials have uniformity in the mesostructure. The detailed luminescence investigation on all the materials show that Eu(tta) 3 pvpd-SBA-16 have the highest luminescence intensity and the materials with taa ligands have longer lifetimes.
Au nanoparticles with different sizes were introduced into the nanocages of a mesoporous material SBA-16 with the aid of chemical modification, leading to new Au-supported catalysts Au/SBA-16. These catalysts were characterized with Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microspectroscopy (TEM), N2 sorption, and X-ray photoelectron microspectroscopy (XPS). These results revealed that uniform Au nanoparticles with sizes of a few nanometers were successfully positioned inside the nanocages of SBA-16. Such catalysts were catalytically active in the oxidative esterification of various alcohols even including less reactive straight-chain alcohols. It was found that the activity of this catalyst strongly depended on the Au loading, and the Au loading of 5 wt % (corresponding to Au particles of 2–3 nm in sizes) led to the highest activity. Its activity was much higher than those of the analogous catalysts prepared from commercial silica gel as well as SBA-15. Furthermore, Au/SBA-16 could be reused at least eight reaction cycles without significant decrease in activity and selectivity. Its recyclability was much superior to that of the catalyst derived from commercial silica gel. The underlying reason may be that the unique nanostructure of SBA-16 can effectively prevent the growth of Au nanoparticles into less active, larger particles, as evidenced from TEM investigations. This study not only supplies a new, active, recoverable catalyst for the green transformations of alcohols to esters but also demonstrates that the three-dimensional mesoporous cage-like material SBA-16 has a superior ability in reducing the diffusion resistance and stabilizing metal nanoparticles against growth.
Sarmad Soomro,Zhenkun Sun,Dennis Y. Lu,Zhihao Zhou,Lin Li,Lunbo Duan
Catalyst deactivation due to carbon deposition and sintering poses a significant challenge to the efficient dry reforming of CH 4 and CO 2 into syngas, particularly at high Ni loadings. To tackle this difficulty, ordered mesoporous silicas with varied pore symmetries were employed as supports in this study to synthesize the Ni-based catalysts using hydrothermal treatment. The 10% Ni/MCM-41 catalyst exhibited the highest conversion rates for CO 2 (81%) and CH 4 (77%), with favourable H 2 /CO (0.92) ratios indicating efficient syngas production Higher Ni concentrations increase active sites and catalytic performance, they also increase carbon deposition, reducing catalyst durability. At lower Ni loadings (4% Ni), catalysts with a 3D pore structure showed improved activity and stability, effectively reducing carbon deposition. This study demonstrates that optimized mesopore symmetries and Ni loadings can enhance catalyst efficiency and durability for syngas production.
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