Microporous and Mesoporous Materials最新文献

Zeolite membranes have excellent application prospects in the separation of mixtures with molecular-level differences; however, the uneven distribution of active ingredients on the support causes defects in the zeolite membranes, limiting their industrial applications. In this study, compact NaX and NaA zeolite membranes with perfect pervaporation performance were prepared in reusable saturated membrane synthesis solutions. These saturated membrane synthesis solutions not only provided sufficient Si/Al components for the even growth of zeolite on the support, but also reduced the random deposition of zeolite particles on the support by reducing the formation of zeolite particles in the bulk solution, improving the quality of the resulting zeolite membranes. The separation factors of the obtained NaA and NaX zeolite membranes were greater than 10000 for the water/ethanol and methanol/MTBE mixtures, respectively. Moreover, the saturated synthesis solutions could be reused multiple times to synthesize zeolite membranes after nutrient supplementation, saving resources and reducing environmental pollution. This study presents reusable solutions for synthesizing compact zeolite membranes, promoting the development of membrane technology for environmental protection and energy conservation.

Phenylboronic acid derivatives have gained interest due to their ability to reversibly bind to 1,2-diols, such as sialic acid receptors overexpressed by breast cancer cells. In this study, two types of mesoporous silica, MCM-41 and SBA-15, were functionalized with 4-carboxyphenylboronic acid (CPBA) through the amidation reaction, and the resulting materials MCM-CPBA and SBA-CPBA were used as carriers for doxorubicin (Dox) or for co-delivery of doxorubicin and resveratrol. In the case of MCM-CPBA material, all amine groups were involved in the condensation reaction with boronic acid derivative, while in the case of SBA-CPBA, free amine groups remained on the silica surface. Dox release profiles, performed in phosphate buffer solution pH 5.5, showed a faster release kinetics of Dox and a higher cumulative drug release for co-delivery system. Larger pores of SBA-15-type carrier influenced the Dox release profile as the diffusion of drug molecules was favored, a higher cumulative drug release being obtained in the case of SBA-CPBA than for MCM-CPBA. Biological assessment of the developed drug delivery systems demonstrated lower cytotoxicity on BJ fibroblasts than on BT474 breast cancer cells. Evaluation of drug delivery systems by hyperspectral microscopy evidenced a higher internalization rate of Dox when was loaded on functionalized silica carriers compared to the free drug into BT474 cells. The internalization rate of doxorubicin-loaded carrier depended on the type of carrier; a better internalization was observed for cancer cells when were treated with Dox-loaded MCM-CPBA nanoparticles than for Dox-loaded SBA-CPBA that might be attributed to smaller size of MCM-CPBA nanoparticles.

Hydroisomerization of long-chain n-alkanes plays a vital role in petrochemical and coal chemical industries, because it can produce high-quality hydrocarbon fuels and lubricant base oils. ZSM-48 (0.56 × 0.53 nm) and ZSM-22 (0.57 nm × 0.46 nm) are characteristic of one-dimensional 10-member ring zeolites suitable for n-alkanes hydroisomerization reaction. Here, the effect of the structure difference between ZSM-48 and ZSM-22 zeolites on hydroisomerization is titrated by the isobutane and n-dodecane. The product distribution of hydroisomerization of isobutane to n-butane shows the reaction pathway on Pt/ZSM-48 and Pt/ZSM-22, in which the monomolecular hydroisomerization of isobutane is involved within the active sites in zeolite channels, while the polymerization-cracking bimolecular reaction occurs on the pore-mouth of zeolite. Pt/ZSM-48 zeolite, possessing larger channel and aperture size than those of Pt/ZSM-22, is more conducive to the diffusion of butane molecules and bimolecular polymerization. Therefore, the isobutane conversion (14 %) on Pt/ZSM-48 produces less C₁+C₂ (1.7 wt% vs. 3.4 wt%) and more C₃+C₅+C₈ (19.2 wt% vs. 16.9 wt%). For the hydroisomerization of n-dodecane, the iso-dodecane selectivity of Pt/ZSM-48 (43.3 wt%) is significantly higher than that of Pt/ZSM-22 (12.4 wt%) at the similar n-C₁₂ conversion (40 %). Compare with the isomers of Pt/ZSM-22, the mono-branched isomers with methyl near the middle of the chains and multi-branched isomers are more easily formed on Pt/ZSM-48, which is conducive to the “key-lock” catalysis mechanism. The larger pore size of ZSM-48 is conducive to n-C₁₂ insertion into zeolite pores, methyl migration and isomer diffusion, and its adjacent pores are more compatible with double-branched isomers. In addition, a high selectivity of C₄∼C₅ alkanes (53.2 wt%) on Pt/ZSM-22 and a high selectivity of C₆∼C₉ alkanes (44.7 wt%) on Pt/ZSM-48 show obvious difference in cracking product distribution, implying different position of methyl groups in i-C₁₂ isomers on Pt/ZSM-22 and Pt/ZSM-48 samples, respectively. The present comparison between Pt/ZSM-48 and Pt/ZSM-22 benefits the selection and development of one-dimensional zeolitesupported metal catalyst in a wide range of hydro-processing reactions.

We report the application of a liquid-mediated defect-healing treatment based on tetraethylammonium (TEA⁺) hydroxide and ammonium fluoride, and variants thereof, to the H⁺ form of zeolite beta. Through comparison between H-beta of high (730) and lower (28.6) SiO₂: Al₂O₃ ratios, and characterisation of the treated samples before and after calcination, insights into the interaction of TEA⁺ and F⁻ with H-beta under hydrothermal conditions were gained. In general, the treatments resulted in the loss of crystallinity and the generation of relatively large mesopores in the more siliceous samples, but improvements in long-range order and the development of relatively small mesopores in the less siliceous samples. The healing of silanol defects was observed for most of the treatments. A partial mechanism is proposed to explain the action of defect-healing treatments based on pore-occupying cations and F⁻; fluorine may be essential in some cases because it balances the charge of the organic cations, preventing the “trapping” of silanol groups as charge-balancing silanolate groups which resist healing.

This study is focused on the use of a hybrid organic-inorganic silica (Silica-SOM) for the removal of Rhodamine B dye (RhB) from water media. Because of its hybrid structure, Silica-SOM has the unique property of being swellable in the presence of an organic solvent, thus increasing the volume available for pollutants adsorption. The adsorption capacity of the Silica-SOM to adsorb RhB from water media has been determined. In particular, if the material is previously swollen with an organic solvent, it is able to sequester more than 99 % of dye molecules in a 1.0 × 10⁻⁵ M RhB solution in less than 1 h at ambient conditions. In addition, the ability of Silica-SOM to be re-generated by mild sonication in ethanol after one RhB adsorption cycle was tested for the first time: the material was easily regenerated and used for six consecutive adsorption cycles; in each of them there is no loss in adsorption performance, which remains quantitatively high and extremely fast.

Zirconium-based metal-organic frameworks (Zr-MOFs) with periodic Lewis acidic nodes have demonstrated impressive catalytic activity in the hydrolysis of organophosphorus nerve agents. Nevertheless, the powdered form of Zr-MOFs and the necessity of a base-buffered aqueous solution during the catalytic reaction pose significant challenges to their practical utilization. In this study, we demonstrate the efficient hydrolysis of an organophosphorus nerve agent simulant, dimethyl-4-nitrophenyl phosphate (DMNP), in both pure water and the solid phase under high humidity conditions, catalyzed by a membrane material. This material, denoted as Im@MOF-808/PVDF, was synthesized through the integration of MOF-808 particles onto PVDF membrane fibers, with imidazole (Im) molecular bases incorporated into the pores of MOF-808. Our findings emphasize the excellent flexibility and processability inherent in Im@MOF-808/PVDF. More notably, it exhibits exceptional catalytic performance in the hydrolysis of DMNP in pure water. Additionally, it demonstrates fair catalytic activity for solid-phase DMNP hydrolysis under high humidity conditions. These features position Im@MOF-808/PVDF as one of the most promising protective materials, showcasing substantial practical applicability.

This study delves into the adsorption behavior of both polar and non-polar molecules on silica surfaces, spanning a range from low coverage to full adsorption scenarios. Our results reveal that isopropanol exhibits a self-competitive adsorption mechanism on the surface. However, due to its thermodynamic stability, we anticipate fully covered pores under experimental conditions. In contrast, n-hexane demonstrates a substantial interaction with the hydrophilic substrate, displaying an enhanced adsorption effect whereby the adsorption gets stronger with an increasing number of molecules adhering to the pore’s surface. As a consequence, we predict a complete coverage of the pores under experimental conditions, accompanied by a discernible reduction in the mobility of these attached molecules. This observation carries significance, as alkanes are typically employed as probing molecules for measuring the geometric tortuosity of silica pores, assuming a reflective surface. Caution is advised, particularly for pores with thin diameters, in the order of a few molecular sizes.

p-Phenylenediamine (PPD) serves as an important intermediate in materials chemistry and is widely used in the preparation of azo dyes and high polymers. However, the discharge of wastewater from industries containing PPD can pose significant threats to both the environment and human health. Herein, a sensitive and reversible β-ketoenamine-based covalent organic framework (TD-COF) fluorescent probe was fabricated with ketoamine-substituted monomers for detection and facile removal of PPD. Abundant carbonyl groups, the regular pores, and the π-conjugated structure of TD-COF are the key features that help facilitate TD-COF interaction with the analyte. Based on these advantages, TD-COF displayed a low detection limit (0.35 μM), high sensitivity, easy visibility, real-time response, and selective interaction with PPD. Simultaneously, the effective removal of PPD and the circulating utilization of TD-COF provide the potential for practical production applications. Regeneration experimental studies indicated that TD-COF retained satisfactory structural stability after five cycles. Furthermore, based on solid-state NMR, X-ray photoelectron spectroscopy, and density functional theory calculations, these studies verified that hydrogen bonding and π-π interaction mechanisms contribute to fluorescence quenching between PPD and the carbonyl of TD-COF. The research demonstrated the utilization of fluorescent COFs for the sensing and removal of PPD, with the potential for extension to the detection of other pollutants.

Herein, we report a facile one-pot in situ self-assembly approach that enables a porphyrin photosensitizer, [5,10,15,20-tetrakis(4-methoxycarbonylphenyl)porphyrin]-Zn(II) (ZnTPP), to be enshrouded by a zeolitic imidazolate framework-8 (ZIF-8) to afford a novel visible-light-driven heterogeneous photosensitizer, ZnTPP@ZIF-8 composite. The ZnTTP photosensitizer was well dispersed and fully confined within the ZIF-8 crystals and the framework intactness and porosity were well maintained. The as-prepared ZnTPP@ZIF-8 composite integrates the advantages of ZIF-8 MOFs and ZnTTP photosensitizer. It not only can effectively produce both singlet oxygen (¹O₂) and superoxide ion (^∙O₂⁻) under visible light irradiation, but also exhibit high surface area and excellent stability. The structure characterization of ZnTPP@ZIF-8 composite was first carried out, and then this material can be used as a heterogeneous photosensitizer for the rapid and highly selective detoxification of a sulfur mustard simulant (2-chloroethyl ethyl sulfide) into the corresponding much less toxic sulfoxide product with a half-life of only 1.5 min under visible light irradiation at room temperature in air atmosphere. This catalyst can be readily recycled and reused at least six times without obvious loss of catalytic activity. This study will provide us a new strategy for the facile, rapid and environmentally friendly preparation of photosensitizer@MOFs composites and the rapid detoxification of sulfur mustard under ambient conditions in the future.

The high efficiency and stability of catalysts are crucial for their practical application in toluene oxidation. Herein, a novel octahedral Pt/Mn₃O₄-110 catalyst with excellent structural stability was synthesized and 100 % toluene conversion can be achieved at low-temperature 160 °C. XRD and Raman results indicated that the structure of Pt/Mn₃O₄-110 can be well maintained after 120 h on-stream reaction, the resistance to H₂O (3 or 5 vol%) and high concentration toluene (3000 ppm)/CO₂ (5 vol%) tests. In situ DRIFTS comparative studies between Pt/Mn₃O₄-110 and Pt/Mn₃O₄-100 (30 % toluene conversion at 160 °C) samples demonstrated that the rate-control steps of toluene oxidation on Pt/Mn₃O₄-110 and Pt/Mn₃O₄-100 were both the further oxidation of benzoate species in the presence of gas-phase oxygen, while the transformation of benzaldehyde to benzoate species was the rate-control step on Pt/Mn₃O₄-100 in the absence of gas-phase oxygen. The weaker Mn-O bonds, richer oxygen vacancies and higher mobility of oxygen species on Pt/Mn₃O₄-110 sample than that of Pt/Mn₃O₄-100 are beneficial for the easier release of lattice oxygen from the surface of catalyst and then participated in toluene oxidation via Mars-van Krevelen mechanism, contributing to easier oxidation of benzaldehyde to benzoate species and formation of formic acid and bicarbonate species.