INORGANIC CHEMISTRY
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2024
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IF 4.3
Ling Pan,Song Ye,Ruihao Huang,Meiyan Wang,Tianning Zheng,Haoran Zhang,Deping Wang
Luminescent silver clusters that are confined inside porous zeolites have attracted great research interest due to the combined advantages of high quantum yield, tunable emission, excellent chemical stability, and desirable adoption ability of this micronano-composite. In this research, a series of Ag-exchanged R-LTA/Ag (R = Li, Na, K) zeolites were synthesized, in which the silver clusters showed blue-shifted excitation in the UV region, red-shifted emission in the visible region, and decreased emission intensity when taking Li+, Na+, and K+ as the extra-framework cations, respectively. The [Ag4(H2O)xR4-sod]6– (x = 2, 4; R = Li, Na, K) structures were constructed, and the TD-DFT method was further carried out to study the influence of extra-framework cations on the luminescence performance of [Ag4]2+ clusters, in which the substitution of Al for Si and the reasonable hydrate levels were both taken into consideration. It is estimated that the S1 and S3 levels for the [Ag4(H2O)4Li4-sod]6– cluster, the S4 level for the [Ag4(H2O)4Na4-sod]6– cluster, and the S5 level for the [Ag4(H2O)2K4-sod]6– cluster can be effectively populated through direct excitation, and the S1 → S0 transition is assumed to be responsible for the radiative emission in the visible region for the [Ag4]2+ pseudo-tetrahedrons. This calculated energy level diagram and simulated absorption spectra of [Ag4(H2O)xR4-sod]6– (x = 2, 4; R = Li, Na, K) clusters explained the modified luminescence property of silver clusters in R-LTA/Ag (R = Li, Na, K) zeolites studied in this research and reported literature.
研究领域:
材料科学
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光物理学
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理论化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
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2016
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IF 5.557
Kai Xu,Chenfang Yuan,Jürgen Caro,Aisheng Huang
In the present work, we report a new road to enhance the gas separation performances of the zeolite Na-LTA membrane by tuning the pore size of zeolite LTA through silver cation exchange. Through the functionalization of the alumina support by using 3-aminopropyltriethoxysilane (APTES), a thin, phase-pure and well intergrown zeolite Na-LTA membrane with a thickness of about 5.0 µm can be facilely prepared on the APTES-modified macroporous α-Al 2 O 3 tube. After a following silver exchange treatment of the as-synthesized zeolite Na-LTA membranes, the sodium ions in zeolite Na-LTA framework are replaced by silver ions , thus forming zeolite Ag-LTA membranes with a narrower pore diameter. The zeolite Ag-LTA membranes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). It is found that both the morphology and structure of the zeolite Na-LTA membrane keep unchanged after silver-exchange, and no cracks, pinholes or other defects are observed in the membrane layer. The zeolite Ag-LTA membrane shows high hydrogen selectivity due to the reduction of pore size of the zeolite Ag-LTA. For the separation of the binary mixture at 50 °C and 2.0 bar, the separation factor of H 2 /C 3 H 8 is α≈120.8, which by far exceeds α≈19.4 of the starting Na-LTA membrane, and are also much higher than the separation factors previously reported for the H 2 /C 3 H 8 mixture on zeolite membranes.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2022
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IF 7.139
Kun Qian,Fang Fang,Yifeng E,Yao Xu,Xiyuan Tong,Peng Chen,Lu Han,Zhuozhe Li
One of the important factors determining the expansion of the application domain of direct methanol fuel cell (DMFC) is its energy density . The bismuth-nickel doped LTA zeolite was as-synthesized in hydrothermal condition and applied into the electrochemistry catalysis of methanol oxidation reaction (MOR) with high performance in the methanol concentration ranging from 0.5 M to 35 M without observed catalyst poisoning . A trace amount of Bi and Ni atoms are highly dispersed on the opening window of the zeolitic surface by the electrochemical rearrangement process. The surface of the LTA structure zeolite is a good carrier for the metal cations with Na cations which could be replaced in hydrothermal crystalline process while the inner direct pores provide a channel for CO gas to escape and prevent catalyst poisoning in electrochemistry progress. Through the comparative study with the Bi doped LTA, Ni doped LTA and the commercial Pt/C catalyst, the Bi and Ni doped LTA reveals higher performance in monatomic catalytic efficiency and electrochemical stability. And through the mutual interaction of diatomic, the doped zeolite material highly improves the energy density of methanol fuel cells and reduces the cost of the cells concerning the absence of noble metals.
研究领域:
材料科学
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电化学
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
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2019
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IF 4.182
Jian Zhang,Ya Wang,Lei Dong,Zhuwen Chen,Yanding Wang,Mei Hong
Micrometer-sized hierarchical LTA-type zeolite crystals with uniform embedded macropores were synthesized via steam-assisted conversion (SAC) of spherical mesoporous silica particles (MSPs) impregnated with alkaline aluminate. The one-pot synthesis was achieved by direct transformation without the need of organic structure directing agents or pre-formed seeds. The obtained cubic hierarchical NaA zeolite materials were 2–5 μm in size which possessed a core-shell structure with a microporous wall in the shell and multi-hollow macropores about 400 nm in the core. Time-series studies revealed the in situ dissolution–crystallization formation mechanism, in which the mesoporous silica particles functioned as silica source as well as “space-filling” template. When the starting MSPs were pre-loaded with metal precursors, multi-hollow zeolite nanoreactor crystals with encapsulated metals were successfully synthesized by this strategy. The present study provides an organic-free way to fabricate hierarchical aluminosilicate zeolites with embedded macropore system.
研究领域:
材料科学
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化学合成
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纳米技术
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催化化学
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无机化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING RESEARCH & DESIGN
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2023
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IF 3.9
Lan Zhang,Keli Zhang,Shengle Kang,Shanshan He,Xiang Dong,Yan Zhao,Fangfang Li,Qihong Cen
Crystalline celluloses , such as microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC), which are originated from biomass, were utilized as templates to prepare hierarchical LTA zeolites . The effect of both size and surface properties of crystalline cellulose on the zeolite synthesis were carefully discussed. As-prepared zeolite based on surface-modification NCC showed hierarchical porous structure with monolithic morphology inherited from nanocrystalline cellulose. Its specific surface area was measured to be 18.3 m 2 /g, which was approximately 3.4 times that of the traditional zeolite A (Z0, 5.4 m 2 /g). Owing to its unique structure, ZNSC facilitated fast Cd(II) adsorption with the adsorption equilibrium time shortened by 81.3%. Kinetics study revealed that intraparticle diffusion was significantly enhanced and the effective diffusion coefficient increased by near 5 times. Furthermore, the maximum adsorption capacity achieved by ZNSC was 324.3 mg/g at 283 K, as calculated from the Langmuir model, which was 1.3 times that of Z0. These results are obtained when the grain size of ZNSC is larger than that of Z0, reflecting the superiority of the hierarchical structure in enhancing adsorption performance and thus providing a facile yet robust strategy for designing hierarchically structured zeolites for rapid and efficient wastewater treatment .
研究领域:
材料科学
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环境工程
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）