JOURNAL OF MEMBRANE SCIENCE
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2025
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IF 9
Pingping Li,Ming Zhang,Yubin Hu,Lei Han,Gang Lou,Pengyuan Wu,Oleksiy Penkov,Junjie Zhao,Kemal Celebi
Mixed matrix membranes (MMMs) with aligned microporous sheets offer enhanced molecular transport. Platelike MFI zeolite crystals can form such MMMs with aligned micropores. However, platelike MFI synthesis suffers from twinning and crystal junctions. Here, we present a method to minimize and preferentially detach these twins and junctions to obtain standalone platelike MFI crystals with high aspect ratios (ca. 4.3 μm by 120 nm). These platelike crystals can be synthesized in kilogram scale and do not aggregate after calcination, exhibiting ∼100 % dispersion yield, in contrast to the ultrathin nanosheets, which lose ∼90 % to aggregation. Twins and crystal junctions are eliminated using a preferential detaching strategy by selectively etching the twin boundaries and junctions. Discrete crystals are aligned in a 2.8 μm thick Pebax matrix to prepare highly b -oriented MFI MMMs with 30 % MFI loading, exhibiting CO 2 permeances up to 37 GPU, and CO 2 /N 2 separation factors up to 16.8 at ambient pressure.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2024
·
IF 4.8
Guojun Lv,Hao Ruan,Xuyang Zou,Yan Chen,Xubin Zhang,Fumin Wang
Solvent-free synthesis method in zeolite preparation can largely decrease the generation of wastewater and improve the zeolite yield by simply grinding and hydrothermal treatment for the solid raw materials, and accordingly is considered as one of the most promisingly green and sustainable synthesis strategy for the metal-doped zeolite materials. However, there are scarcely any reports on the solvent-free synthesis and catalytic application of tungsten-doped zeolite materials. In this work, tungsten-doped MFI zeolites were prepared with solvent-free synthesis method and used as heterogeneous catalyst for cyclohexene epoxidation reaction. The synthesized tungsten-doped MFI zeolites displayed a monoclinic (P21/n) space group attributed to the successful incorporation of tungsten atom into MFI framework and meanwhile possessed an enormous number of irregular mesopores ranging from 2 nm to 50 nm. The influence of TPAOH addition amount on the mesopore structure and properties of tungsten-doped MFI zeolite was further investigated. In addition, the crystallization process of tungsten-doped MFI zeolite sample was tracked and analyzed with SEM, XRD and BET characterizations, and accordingly possible formation process for hierarchical zeolite was proposed. Furthermore, the prepared hierarchical tungsten-doped MFI zeolite displayed eminent cyclohexene epoxidation performance and re-usability for more than five times. This work provides some guidance for the solvent-free synthesis of metallosilicate zeolites, decreasing the generation of wastewater and improving the zeolite yield.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2017
·
IF 2.843
Zhen Sun,Yueer Yan,Gang Li,Yahong Zhang,Yi Tang
A facile and fast microwave-assisted approach without any other pre/post-treatment has been proposed to hydrothermally synthesize six kinds of MFI-type heteroatom (Mn, Ga, Ti, Sn, Cr, Zr) zeolites. By comparing with oven heating mode, it is found that microwave field displays a positive effect on the introduction of partial heteroatoms in the zeolite framework. Moreover, differing from the conventional heating, microwave irradiation displays different influences on the different heteroatom zeolites because different heteroatoms cause different polarities and wave-absorption abilities of M–O bonds under microwave irradiation. Furthermore, this positive effect of microwave is embodied not only on heteroatom zeolite synthesis and heteroatom state in zeolite framework but also the resultant catalytic performance. This finding provides an easy route for the synthesis of novel heteroatom zeolite being difficult to prepare by conventional mode, along with a new direction for the exploration of microwave effect.
研究领域:
材料科学
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化学工程
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催化研究
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Molecular Catalysis
·
2026
·
IF 4.3
Hao Gu,Qiaoyun Qin,Ting Yang,Hongxia Liu,Jiayuan Yu,Jinfeng Wang,Changjiu Xia,Lei Liu
T4, T11, T10, and T8 are the most favorable Ti substitution sites in S-1. • In MFI-type zeolites, hydroxyl nest defects preferentially form at the T10-T1, whereas tripodal(1I) defects are most favorable at the T11-T10. • Compared with tripodal(1I) defects, the formation of hydroxyl nest defects is more sensitive to Ti incorporation and easily formed. • In TS-1, hydroxyl nest defects show stronger Lewis and Brønsted acidity compared with tripodal(1I) defects. Although MFI-type zeolites have been extensively studied, the formation of framework defects and their preferential siting at different framework positions remain difficult to accurately predict, which largely hampers the realization of defect engineering and precise defect control. In this study, density functional theory was used to study the preferred Ti substitution sites in S-1 zeolite. The results showed that T4, T8, T10, and T11 were the most favorable sites for Ti incorporation, and cluster models centered on these four representative sites were constructed as the main research objects to further analyze the formation sites and spatial distributions of hydroxyl nests and tripodal(1I) defects. These findings revealed that hydroxyl nest defects are most stable at Ti-T10-T1 sites in TS-1, whereas tripodal (1I) defects preferentially form at Si-T11-T10 sites in S-1, indicating that framework positions strongly affected the preference of defect site. Moreover, Ti incorporation markedly lowers defect formation energies, indicating that TS-1 is intrinsically more prone to defect formation than S-1, although the most stable defect configurations remain unchanged. Hydroxyl nest defects were more sensitive to Ti substitution, while tripodal(1I) defects were relatively unaffected. Furthermore, the optimal formation sites and acidity of two representative framework defects (hydroxyl nests and tripodal(1I) defects) in both S-1 and TS-1 were analyzed, and demonstrated that hydroxyl nest configurations in TS-1 exhibited stronger Lewis and Brønsted acidity. This study deepens the understanding of preferential framework defect sites and Ti substitution effects in MFI-type zeolites, providing theoretical guidance for defect-engineered design. Schematic illustration of the preferential formation sites of hydroxyl nest and tripodal(1I) defects in S-1/TS-1 and their Lewis and Brønsted acidity in TS-1. Download: Download high-res image (232KB) Download: Download full-size image
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MICROPOROUS AND MESOPOROUS MATERIALS
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2019
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IF 4.182
Dongxue Guo,Chengxiang Shi,Hui Zhao,Rui Chen,Shaohua Chen,Pingchuan Sun,Tiehong Chen
Many great efforts have been devoted to the synthesis of hierarchically zeolites due to their potentially significant technological applications for catalytic reactions involving bulky reactant/products. In this work, we report a facile hydrothermal route to prepare mesoporous silicalite-1 with plentiful intracrystalline mesopores (5–20 nm) using poly (acrylic acid) (PAA) as a mesoscale template. During the crystallization process , the PAA chains served as the space occupant for intracrystalline mesopores, meanwhile, a small amount of amphiphilic organosilane (dimethyloctadecyl-[3-(trimethoxysilyl)-propyl]-ammonium chloride, TPOAc) acted as auxiliary template to enhance the connection between the growing crystal domains and the PAA chains. After calcination , the mesopore template PAA chains were burned out, and zeolite with intracrystalline mesopores could be obtained, giving rise to a combination of type I & IV N 2 adsorption/desorption isotherms. The alkali metal salts in the synthesis system facilitated the formation of mesoporous structured zeolites. In order to enhance the acidic sites, mesoporous zeolite Al-ZSM-5 with intracrystalline mesopores was also synthesized by introducing aluminum source in the synthesis.
研究领域:
材料科学
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催化化学
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无机化学
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纳米技术
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多孔材料
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MICROPOROUS AND MESOPOROUS MATERIALS
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2023
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IF 5.2
Xuyang Zou,Jiangzhang Wang,Guojun Lv,Tao Wang,Chaoyi Zhou,Yan Chen,Jialing Shen,Shihao Su,Zhongmin Liu
Impregnation handlement can load highly dispersed CuO nanoparticles on the Fe-MFI zeolite and effectively enhances its catalytic activity in the tetracycline degradation reactions, but encounters serious re-usability problems. In this work, Fe-MFI zeolite-encapsulated copper oxide CuO@Fe-MFI was prepared via one-step hydrothermal synthesis and utilized as heterogeneous catalyst for the removal of tetracycline. The obtained 2CuO@1Fe-MFI zeolite presented a external surface area of 270 m 2 /g, which was almost 5.5 folds of 2CuO/1Fe-MFI zeolite obtained by impregnation handlement. In addition, there may be a near-neighbor effect between encapsulated CuO and framework iron evidenced by the shifts of UV–Vis absorption bands as well as binding energies for Fe 2p and Cu 2p. At pH = 7.0, 2CuO@1Fe-MFI zeolite attained the largest tetracycline removal rate of 99.6% within 20 min at experimental conditions: [TCE] = 50 mg/L, [Catalyst] = 0.5 g/L, [PMS] = 1.0 g/L, 323 K, and the biggest degradation rate constant of 2.42 min −1 , which was almost 11.1 folds of that for 2CuO/1Fe-MFI zeolite. The large external surface area and near-neighbor effect together gave rise to the excellent tetracycline degradation performance for 2CuO@1Fe-MFI zeolite. On the same time, the obtained 2CuO@1Fe-MFI zeolite can be reused for more than five times. Quenching experiments and EPR characterizations demonstrated the reactive species for tetracycline removal over 2CuO@1Fe-MFI zeolite were •OH, SO 4 • − , •O 2 − and 1 O 2 species, and moreover 1 O 2 served as the major active species. Furthermore, possible tetracycline degradation pathways over 2CuO@1Fe-MFI zeolite were proposed.
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Nanomaterials
·
2022
·Vol. 12
·期 10
·1633
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IF 5.719
Yuan Hu,Chan Wang,Tiesen Li,Xiaojun Bao,Yuanyuan Yue
Aluminum-rich hierarchical MFI-type zeolites with high acidic-site density exhibit excellent activity and selectivity in bulky molecule-involved reactions. However, it is challenging to develop a facile and environmentally benign method for fabricating them. Herein, we employ a polymer that does not contain nitrogen and halogen elements to successfully synthesize aluminum-rich hierarchical ZSM-5 zeolite with a Si/Al ratio of 8 and a significant number of mesopores comprised of oriented-assembled nanocrystals. It is demonstrated that the nitrogen- and halogen-free polymer is instrumental in the formation of the ZSM-5 zeolite by serving as a template for constructing the hierarchical micro/mesoporous structure. Moreover, this polymer also acts as a crystal growth modifier to form a single-crystalline zeolite. Notably, the resultant zeolite shows a better catalytic performance in converting waste plastic into hydrocarbons than a commercial one. Our work enables the synthesis of high-quality hierarchical zeolites without requiring quaternary ammonium templates.Keywords:hierarchical ZSM-5 zeolites;aluminum-rich;nitrogen- and halogen-free polymer;waste plastics cracking
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SEPARATION AND PURIFICATION TECHNOLOGY
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2024
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IF 8.1
Qiancheng Zheng,Huayu Zhang,Jun Li,Xingtong Yu,Xinyi Gao,Zhengbao Wang
Hierarchical and two-dimensional (2D) zeolites have drawn much attention in catalysis and separation process due to their fast mass transfer. However, the facile manipulation in controllable mesopore volumes and morphologies for hierarchical nanozeolites is full of challenges. Herein, a facile strategy is presented for the synthesis of single-crystalline 2D hierarchical MFI zeolite nanosheets (HNSs) with tunable mesopore volumes through the amino acid-assisted crystallization of nucleated amorphous silicon precursors (NASPs). The tailored synthesis of HNSs with controllable aspect ratios (( L c + L a )/ L b ), b -axis thicknesses (a few tens of nanometers) and mesopore volumes is achieved by adjusting the preparation of the NASPs and the amount of amino acid in the synthesis mixture. The HNSs exhibit large BET surface area (>400 m 2 g -1 ), high micropore volume (0.16–0.18 cm 3 g −1 ) as well as rich mesopore volume (>0.10 cm 3 g −1 ), indicating the high crystallinity of the hierarchical zeolite nanosheets. Specially, the higher adsorption capability and faster adsorption rate for the dye (Rhodamine B) adsorption demonstrate the excellent performance of the hierarchical zeolite nanosheets, which exhibits the maximum adsorption capacity of 115.7 mg g −1 . The controllable manipulation of mesoporous volumes and morphologies in MFI zeolites represents a significant contribution to the field of zeolite microstructure engineering.
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ACS Applied Materials & Interfaces
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2024
·
IF 8.3
Jiajie Ye,Xuan Tang,Lu Cheng,Shoujie Zhang,Wangcheng Zhan,Yanglong Guo,Li Wang,Xiao-Ming Cao,Kuan-Wen Wang,Sheng Dai,Yun Guo
Metal/metal oxide clusters possess a higher count of unsaturated coordination sites than nanoparticles, providing multiatomic sites that single atoms do not. Encapsulating metal/metal oxide clusters within zeolites is a promising approach for synthesizing and stabilizing these clusters. The unique feature endows the metal clusters with an exceptional catalytic performance in a broad range of catalytic reactions. However, the encapsulation of stable FeOx clusters in zeolite is still challenging, which limits the application of zeolite-encapsulated FeOx clusters in catalysis. Herein, we design a modified solvent-free method to encapsulate FeOx clusters in pure siliceous MFI zeolites (Fe@MFI). It is revealed that the 0.3–0.4 nm subnanometric FeOx clusters are stably encapsulated in the 5/6-membered rings intersectional voids of the pure siliceous MFI zeolites. The encapsulated Fe@MFI catalyst with a Fe loading of 1.4 wt % demonstrates remarkable catalytic activity and recycle stability in the direct oxidation of methane, while also promoting the direct oxidation of cyclohexane, surpassing the performance of conventional zeolite-supported Fe catalysts.
研究领域:
化学
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材料科学
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催化反应
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MICROPOROUS AND MESOPOROUS MATERIALS
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2022
·
IF 5.876
Yihong Rong,Xiangping Zhang,Hongyan Wang,Deming Tan,Hui Wang,Tao Zhang
The mechanochemically-assisted solvent-free (or minimal-solvent) method, compared with the traditional hydrothermal method , exhibits the merits of reduced waste generation, high yields, and fewer safety problems, thus offering new opportunities for the green fabrication of zeolitic materials. This promising synthetic strategy, however, tends to suffer from a severe aggregation of zeolite crystals. Herein, we report the synthesis of a series of well-dispersed MFI-type zeolites with various compositions via a mechanochemical route using imidazolium ionic liquids as additives. The crystal dimensions along a -, b -, and c -axis of the obtained coffin-like silicalite-1 zeolites can easily be controlled by varying the concentration of ionic liquids or the alkyl chain length of ionic liquid cations. This imidazolium ionic liquids-assisted mechanochemical approach can also work equally well with the heteroatom-containing MFI zeolites (e.g. Al-MFI and B-MFI). In addition, it is found that the imidazolium ionic liquid can be recycled for further use.
研究领域:
材料科学
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绿色化学
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机械化学
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沸石合成
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纳米材料
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CHINESE JOURNAL OF CATALYSIS
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2026
·
IF 17.2
Haodong Xie,Yumeng Fo,Hongwei Zhang,Hua Xu,Xiao Zhang,Yingshuo Guo,Runze Li,Ruolin Zhang,Guilin Liu,Xicheng Jia,Jiazhou Li,Yuming Zhang,Meizan Jing,Weiyu Song,Wenhao Luo,Zhijie Wu
Developing efficient Pt-based catalysts is crucial for sustainable lactic acid (LA) production via glycerol oxidation. Herein, we synthesized a series of robust PtIn/Sn-MFI catalysts with low Pt loading of 0.5 wt% for glycerol oxidation under base-free conditions. The PtIn/Sn-MFI catalysts with varying In contents exhibited a volcano-shaped trend between turnover frequency (TOF) and In/Pt molar ratio. Among all tested catalysts, the Pt 0.5 In 1.0 /Sn-MFI sample exhibited the highest catalytic activity (1283 h –1 ), achieving 96.8% glycerol conversion with 73.5% LA selectivity, surpassing the monometallic Pt 0.5 /Sn-MFI catalyst. Furthermore, the Pt 0.5 In 1.0 /Sn-MFI catalyst maintained excellent stability, with no significant degradation in catalytic performance even after five consecutive recycling runs. Experimental analysis and characterizations verified the formation of PtIn 2 nanoalloys, accompanied by electron transfer from In to Pt, which significantly enhanced the catalysts’ O−H bond activation ability, resulting in high activity and selectivity. Combined with kinetic studies and density functional theory calculations, we further revealed that PtIn 2 nanoalloy active sites significantly reduce the activation energy barrier for the dehydrogenation of the secondary hydroxy group in the reaction pathway. This work offers new perspectives on the rational design of cost-effective, high-efficiency catalysts for the sustainable oxidation of glycerol to LA.
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Nature Communications
·
2026
·
IF 18.1
Li Pingping,Zhang Ming,Hu Yubin,Dai Xiangcheng,Asif Muhammad Mohtashim,Zhao Junjie,Kim Donghun,Celebi Kemal
Zeolite nanosheets offer promising opportunities to fabricate ultrathin molecular sieving platforms for energy-efficient and cost-effective gas separation. However, activating these nanosheets requires a high-temperature calcination process that opens the pores, causing drying and subsequent irreversible aggregation. Once aggregated, most nanosheets cannot be well-aligned to form a continuous thin membrane, which is a persistent bottleneck for mixed matrix membrane fabrication. In this study, we present a facile ultraviolet (UV)-ozone treatment that activates zeolite nanosheets (MFI and SAPO-34) in aqueous solution. This treatment prevents the drying and aggregation of the nanosheets, thereby ensuring high yields of solvent dispersion for open-pore nanosheets. Furthermore, the UV-ozone treatment also introduces hydroxyl groups on the nanosheet surface that enhance both CO 2 adsorption and interfacial compatibility with the polymer matrix. The activated nanosheets are then used to fabricate micrometer-thick, highly b -oriented MFI mixed matrix membranes on polymer substrates via solution casting. These membranes demonstrate high CO 2 /N 2 selectivity of 40 ± 6, with permeance of 194 ± 50 GPU (at 25 °C, ambient pressure). This method is thus substantiated as an effective and scalable approach for activating zeolite nanosheets and can be a cost-efficient approach for the fabrication of thin, flexible zeolite-nanosheet-based gas separation membranes.
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