FUEL
·
2020
·
IF 5.578
Chenyao Bi,Xu Wang,Qing You,Baoyu Liu,Zhuo Li,Jianbo Zhang,Qingqing Hao,Ming Sun,Huiyong Chen,Xiaoxun Ma
Five MFI-type zeolite catalysts, which were aluminosilicate ZSM-5 (Z5), gallium-substituted silicalite-1 (Ga-S1), mesoporous ZSM-5 (MZ5), gallium-substituted mesoporous silicalite-1 (Ga-MS1) and gallium-substituted mesoporous ZSM-5 (Ga-MZ5), were hydrothermally synthesized with combined using of TPAOH and TPOAC as micropore and mesopore structure-directing agents respectively, followed by the application in the catalytic upgrading of volatiles from low-rank coal fast pyrolysis. The obtained results indicated that significant improvements with the yield of high value-added products of BTEXN (benzene, toluene, ethylbenzene, xylene and naphthalene) increased from 5.4 mg.g −1 to 11.9–26.4 mg.g −1 , as well as the content of light fractions (<300 °C) in coal tars increased from 51% to 65–88% were realized by using the representative MFI-type zeolite catalysts in contrast to non-catalyst pyrolysis. Moreover, the possible mechanism for catalytic upgrading over the best-performing catalyst of gallium-substituted mesoporous ZSM-5 (Ga-MZ5) with the highest yield of aromatics and effective reduction of phenols was proposed on the basis of systematic comparison of structural features and catalytic performances of various MFI-type zeolite catalysts and fundamental study of the synergetic effects dominated by acidity, ratio of Brønsted/Lewis acid sites, intra-/extra-framework gallium species and hierarchical meso-/microporosity.
研究领域:
能源化学
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
Particuology
·
2017
·
IF 2.621
Rongjie Ling,Wu Chen,Jin Hou
Modified nanosized MFI (ZSM-5 and silicalite-1) zeolites were successfully synthesized by a hydrothermal method using aluminum isopropoxide and tetraethylorthosilicate as the raw materials. The synthetic zeolites were characterized by X-ray diffraction, energy dispersion spectroscopy, and scanning electron microscopy. The ZSM-5 and silicalite-1 zeolites exhibited ellipse-like and cubic columns, respectively. The K + ion-exchange equilibrium and ion-exchange capacity of the synthetic zeolites in seawater were investigated. The K + ion-exchange of synthetic zeolites was rapid and reached an ion-exchange balance in approximately 20 min. The K + ion-exchange capacity of ZSM-5 and silicalite-1 in seawater was 56.7 and 48.7 mg/g, respectively. The synthetic zeolites have high selectivity toward K + , and therefore, they can be used to selectively extract potassium from seawater.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Omega
·
2024
·
IF 3.7
Jin Quan Tao,Yi Jing Jia,Yan Cui,Tian Yu Bai,Xi Nan Xue,Rong Peng Yao,Ya Song Zhou,Qiang Wei
The synthesis of zeolites through more efficient, environmentally friendly, and cost-effective methods was deemed significant in both industrial applications and academic fields. Conventional hydrothermal synthesis strategies have encountered difficulties in producing pure silica MFI zeolite (silicalite-1) under amine-free conditions. This was primarily attributed to the competitive growth of quartz, keatite, or magadiite during the crystallization process. In this work, it was found that the lack of nucleation ability was an important reason for the poor crystallization stability of the methanol solution. Well-crystallized silicalite-1 zeolites with uniform particle sizes were achieved through the cooperative guidance of methanol and seed crystals. Large-scale experiments with silicalite-1 zeolite demonstrated good reproducibility. Combined with the TG-IR and N2 adsorption–desorption results, it was observed that, when an extremely small amount of seed (0.97 wt %) was introduced, methanol could play a role as a crystallization promoter in the hydrothermal synthesis system. Furthermore, a lower alkaline-to-silica ratio and water-to-silica ratio were conducive to the progression of the crystallization process. In summary, this work presented a hydrothermal synthesis strategy for the synthesis of silicalite-1 zeolite in a methanol solution without the need for a large amount of seeds and provided an effective pathway for the low-cost, large-scale production of silicalite-1 zeolite.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CRYSTAL GROWTH & DESIGN
·
2024
·
IF 3.2
Rui Wang,Ruilan Xu,Kaipeng Zhang,Lu Gan,Xintu Lin,Shangxi Zhang,Yong Peng
Preventing the appearance of fog on transparent glass is an important issue not only in our daily lives but also in scientific research and clinical diagnosis. A zeolite molecular sieve with MFI-type structure was identified as a very promising antifog material. In this work, MFI zeolite films with different microstructures were prepared by the solvothermal secondary growth method using diols including ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), and tetraethylene glycol (tEG) as solvents. The elimination mechanism of new MFI twin crystals was demonstrated based on scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) characterizations of the resulting films and the mother solutions. The twin-free MFI films with b-axis preferred channel orientation exhibited both higher light transmittance and lower haze compared with the a-&b-mix-oriented film. The employment of diol solvents facilitated the generation of a surface Si–OH group on the films, leading to the improvement of film hydrophilicity. By taking advantages of the high transparency and hydrophilicity, the b-oriented MFI films synthesized on glass substrate achieved good antifogging performance.
研究领域:
材料科学
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光学
·
表面科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2025
·
IF 9
Li Peng,Li Zhao,Guang Pan,Xuehong Gu
The separation of CO 2 from N 2 using MFI-type zeolite membranes relies on a mechanism dominated by adsorption and diffusion processes. In this investigation, we employed a tungsten (W) doping approach to elevate the CO 2 separation selectivity of MFI zeolite membranes. Isothermal adsorption assessments demonstrated an elevated heat of adsorption (Q st ) for CO 2 and a reduced pore sizes after W doping, corroborating the enhanced CO 2 /N 2 separation efficiency observed. Specifically, the W-doped MFI membrane exhibited a selectivity of 38.8 under dry conditions, a substantial improvement over the 8.7 selectivity achieved by the undoped Si-MFI membrane, while the CO 2 permeance remained comparable (3.9 × 10 -7 vs 4.5 × 10 -7 mol·m -2 ·s -1 ·Pa -1 ). Furthermore, the incorporation of tungsten curtails the formation of silanol groups by stabilizing the zeolite framework via energetically favorable W-O-Si linkages. These linkages diminish silanol-related defects, typically prone to water adsorption, thereby enhancing the membrane’s hydrophobicity. Consequently, the W-doped MFI membrane maintains a CO 2 /N 2 selectivity of 29.5 and a CO 2 permeance of 1.8 × 10 -7 mol·m -2 ·s -1 ·Pa -1 in the humid environments, outperforming most reported zeolite membranes and showing potential ability for practical post-combustion carbon capture applications.
研究领域:
材料科学
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环境工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2019
·
IF 1.911
Zhipeng Chen,Jiajin Huang,Qiaowen Mu,Huiyong Chen,Feng Xu,Yanxiong Fang,Baoyu Liu
The modification of pillared MFI zeolites was performed by nitridation of silica pillared MFI zeolite nanosheets under NH 3 atmosphere with different time. The resultant zeolites were characterized by a complementary combination of X-ray power diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), pyridine-IR spectroscopy and N 2 adsorption–desorption isotherms. The analyses showed that the nitridation didn't destroy the crystallinity and specific surface area of zeolites, and the acidity of zeolites can be tailored by tuning the time of nitridation, resulting in the different concentration ratios of Brønsted-to-Lewis (B/L) acid sites. Moreover, the nitrided zeolites exhibited high selectivity to 2-benzyl-1,3,5-trimethylbenzene than parent silica pillared MFI zeolite nanosheets in benzylation of mesitylene with benzyl alcohol . A balance between Brønsted acid sites and Lewis acid sites can inhibit the self-etherification of benzyl alcohol and enhance the selectivity of alkylated product. These experimental data implied that nitridation was an effective method to modulate the acidity of zeolites and the synergy between Brønsted acid sites and Lewis acid sites was a decisive factor to determine the selectivity.
研究领域:
化学工程
·
催化材料
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2025
·
IF 3.7
Xinyi Gao,Qiancheng Zheng,Zhengbao Wang
The preparation of dispersible MFI-type zeolite nanoparticles with open micropores is challenging. Herein, a rapid and effective ultrasound-assisted liquid-phase exfoliation method along with a freeze-drying process for redispersion of calcined Silicalite-1 (S-1) zeolite nanoparticle aggregates using 3-aminopropanol as an exfoliating agent is demonstrated. The exfoliation of S-1 zeolite nanoparticles is characterized by X-ray diffraction, scanning electron microscopy and DLS particle size analysis. The effects of drying methods of as-synthesized zeolite nanoparticle suspension, zeolite contents in frozen nanoparticle suspension, exfoliating agent concentrations, and zeolite doses in ultrasonic suspension on exfoliation efficiency are systematically investigated. It is found that the S-1 zeolite nanoparticle (∼70 nm) achieves a yield up to 95 % through a 30 min ultrasonic exfoliation in a 3-aminopropanol solution along with a freeze-drying process. The proposed exfoliation mechanism involves two primary stages: guest molecule insertion followed by water expansion, both substantially enhanced by tip sonication. This work offers a comprehensive understanding of the exfoliation process, provides valuable insights into the dispersion of sintered zeolite nanoparticles.
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
MICROPOROUS AND MESOPOROUS MATERIALS
·
2019
·
IF 4.182
Xixi Ma,Xiaocao Wu,Jürgen Caro,Aisheng Huang
A seeding-free synthesis strategy was developed for the preparation of dense and phase-pure MFI zeolite membranes based on “like grows like” principle. Through covalent modification of the porous ceramic supports by using 1H,1H,2H,2H-perfluoroalkyltriethoxysilanes (POTS), the support surface was changed from hydrophilic to hydrophobic, which promotes the nucleation and growth of hydrophobic MFI zeolite membranes. Thin, well-intergrown and phase-pure MFI zeolite membranes, with a thickness of about 2.0–3.0 μm, can be facilely prepared on POTS-modified supports like Al 2 O 3 and TiO 2 at 175 °C for 24 h. No cracks, pinholes or other visible macroscopic defects are observed in the membrane layer. The MFI zeolite membranes were evaluated in the hydrophobic separation of 5.0 wt% ethanol/water mixture at 75 °C by pervaporation . The MFI zeolite membrane prepared on the POTS-modified TiO 2 disk shows high pervaporation separation for ethanol recovery. At 75 °C, a separation factor of 103 and total flux of 2.56 kg/m 2 h can be obtained, which is promising to extract bio-alcohols from the fermentation broth.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2020
·
IF 4.551
Haoyang Zhang,Xiaotong Yang,Xiaojing Song,Xinyu Chang,Mingjun Jia
A series of tungsten-tin bimetallic MFI type zeolites (WSn-MFI) with different Sn and W contents were hydrothermally synthesized using tetrapropyl ammonium hydroxide (TPAOH) as a template and polypyrrolidone as a co-surfactant. Tetraethylorthosilicate (TEOS), ammonium tungstate hydrate and tin (IV) chloride pentahydrate were used as the Si, W and Sn sources, respectively. The resultant samples were characterized by various techniques, and were evaluated as catalysts for the epoxidation of cyclohexene with hydrogen peroxide. The results reveal that all the W–Sn bimetallic zeolites have the typical MFI structure, and their relative crystallinities and morphologies change somewhat with the variety of W and Sn contents. Both the isolated framework SnO 4 species and the extra-framework SnO 2 species could be detected in all WSn-MFI samples, while only trace amount of extra-framework W species are present inside the channels/cages of the bimetallic zeolites. Compared with the monometallic zeolites of W-MFI and Sn-MFI, the bimetallic WSn-MFI zeolites exhibit much higher catalytic activity for the epoxidation of cyclohexene. Of these, the sample named WSn-MFI-a could efficiently convert cyclohexene to the corresponding epoxide with a high yield of 79% under an optimized reaction condition. A synergistic effect between the W and Sn species should play critical role in improving the catalytic activity and the epoxide selectivity of the bimetallic zeolite catalysts.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Zhanbo Guo,Chao Feng,Zongnan Shen,Xun Deng,Xinrong Feng,Min Deng,Jie Liu,Wenju Jiang,Lin Yang,Lu Yao,Zhongde Dai
Membranes have been considered as promising alternatives for natural gas sweetening. Mixed matrix membranes (MMMs) possess superior gas separation performance and the potential to combine varieties of polymers and filler materials. In the current work, MMMs have been fabricated via employing Tröger’s base (TB) polymer and zeolites with three different morphologies. Simultaneously, CO2/CH4 and H2/CH4 separation performances of the obtained MMMs were comprehensively investigated. It is found out that the presence of the MFI-type zeolites significantly improved the gas permeability, but the selectivity was somehow reduced. Among the three different nanofillers, nanosheet zeolite-based MMMs presented the highest gas permeability; with 20 wt % nanosheet zeolites, both CO2 and H2 permeabilities were increased to 348.6 and 441.5 Barrer, which were improved by 522.0 and 256.2%, respectively. In addition, SEM, XRD, FTIR, and TGA were also employed to characterize the obtained MMMs.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2022
·Vol. 12
·期 25
·16131-16140
·
IF 4.036
Qiu-Ping He,Ying-Ying Wang,Peng-Fei Wang,Xiao-Ming Dou
Zeolite–polymer composite membranes have become promising and effective materials for the pervaporative separation of liquids, especially for isomeric mixtures. In this paper, silicalite-1/PDMS composite membranes have been used to investigate the separation of dichlorobenzene (DCB) isomers via pervaporation for the first time. Silicalite-1 zeolites modified by the silane coupling agent, NH3–C3H6–Si(OC2H5)3, have been incorporated into polydimethylsiloxane (PDMS). Then, the silicalite-1/PDMS composite membranes have been successfully prepared on porous polyvinylidene fluoride (PVDF) supports. The morphology and structure of the silicalite-1 zeolites and silicalite-1/PDMS composite membranes have been characterized by XRD, FTIR, SEM and BET techniques. The results show that the modified silicalite-1 zeolite particles have smaller pore sizes dispersed more uniformly in the active layers of the silicalite-1/PDMS composite membranes and present fewer aggregation and pinholes formed by the accumulation of zeolite particles. The silicalite-1/PDMS composite membranes are all dense and continuous with good homogeneity. To evaluate the pervaporative separation performance of the DCB isomers, the unmodified and modified silicalite-1/PDMS composite membranes have been further tested in single-isomer and binary-isomer systems at 60 °C. The modified silicalite-1/PDMS composite membranes present higher DCB isomer separation factors. The separation factors of the modified silicalite-1/PDMS composite membranes in the binary-isomer systems for p-/o-DCB and p-/m-DCB are 3.53 and 5.63, respectively. The permeate flux of p-DCB through the modified silicalite-1/PDMS composite membranes in the p-/o-DCB binary-isomer system is 116.7 g m−2 h−1 and in the p-/m-DCB binary-isomer system, it is 93.5 g m−2 h−1. The result provides a new approach towards the pervaporative separation of DCB isomers from their mixture for future industrialization applications.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Peng Zhang,Fan Yang,Xuedong Zhu,Weizhong Zheng
In this work, a kind of ZSM-5 zeolite with one-dimensional fins growing along the [010] direction has been successfully synthesized utilizing both tetrapropylammonium hydroxide (TPAOH) and tetramethylammonium hydroxide (TMAOH) as co-templates. With the aid of molecular dynamic simulations and a series of experimental evidences, the formation mechanism of the one-dimensional feature is determined to arise from the synergic effects between TPA + and TMA + . Two TPA + and three TMA + would co-exist in a unit MFI cell at a certain crystallization period depending on the composition of zeolite and precursor, and this configuration ensures a minimum stabilization energy required for the growth along [010] direction. Investigations manifest these needle-like fins with diameters of ca. 60 nm could function as pseudo nano crystals and introduce additional pores ranging from 10 to 90 nm, which effectively promotes the diffusion capability and substantially improves the catalytic performance in propane aromatization.
研究领域:
材料科学
·
催化化学
✓ 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）