MICROPOROUS AND MESOPOROUS MATERIALS
·
2016
·
IF 3.349
Chen Liu,Lu Bai,Jianming Zhang,Deng Hu,Meng Li,Gaofeng Zeng,Yanfeng Zhang,Wei Wei,Yuhan Sun
Rapid synthesis and characterization of all-silica Deca-Dodecasil 3 Rhombohedral (DD3R) zeolite were systematically studied with (NH 4 ) 2 SiF 6 as silica source. The effects of gel recipe, synthesis temperature and time, seeding, aging and silica source were investigated systematically. Big DD3R crystals (50–150 μm) with various morphologies (hexagonal plate, polyhedron and rhombohedron) were obtained by tuning the synthesis temperature, time, seeding and aging. Compared with other silica sources, (NH 4 ) 2 SiF 6 is very reactive which enhances the nucleation and crystal growth of DD3R zeolite significantly. At 220 °C, highly crystalline DD3R was obtained in 12 h without seeding, which is the fastest synthesis up to now. Aging and seeding reduced the synthesis time substantially and led to smaller crystals. With the help of seeding and aging, pure DD3R crystals were obtained in 6 d at 100 °C, which opens the door to synthesis at low temperature and ambient pressure. Mixed silica sources can reduce the consumption of expensive (NH 4 ) 2 SiF 6 . Higher calcination temperature is required for the complete template removal of the big DD3R crystals obtained in this study, which hinders the diffusion of oxidation products from the template. Zeolites SGT and DOH are competing phases in the synthesis of DD3R. The introduction of Al into the mother liquor led to the formation of zeolite SGT.
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
MATERIALS SCIENCE FORUM
·
2020
·
IF 0
Zhi Wei He,Hong Xiao Lin,Chun Yan Li,Ashok M. Mahajan,Swati A. Gupta,Mei Zhou
Effect of various silicon sources, such as TEOS, MTES mixed with TEOS and 1,3,5-tris(triethoxymethyl) on SiO2 films was investigated. The synthesized solutions were used as silicon sources to prepare silica-like backbone films. The investigation showed that all precursors can able to produce the flat and uniform films. An FTIR spectrum confirmed the formation of SiO2 in film matrix. The results indicated that the internal microstructure of each film is different. The incorporation of less polar bonds such as F and C was carried out using various Si sources, while the introduction of these sources confirmed through FTIR spectra. Optical properties of the films were carried out by using ellipsometric porosometry (EP) measurement. The leakage current density for the films prepared by using TEOS, MTES and 135TTEB was observed to be 2.8 × 10-7 A/cm2, 2.9 × 10-8 A / cm2, and 4.1 × 10-6 A / cm2, respectively, at 1 MV/cm electric field strength by the IV curves obtained by semiconductor characterization after fabricating MIS devices. The calculated dielectric constants from RI of the deposited SiO2 films were 2.0, 1.9 and 2.5 respectively. When the microstructure of the precursor solution changed, the introduction of atomic morphology or terminal inerted group ratio changed the internal bridging mode of SiO2, and thereby significantly reduced the dielectric constant and improved insulation.
研究领域:
材料科学
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电子工程
✓ 已验证
DOI
Energies
·
2024
·Vol. 17
·期 9
·2180
·
IF 3
Xicheng Wang,Wentao Xia,Wenlong Xu,Zengqiao Chen,Xiaohan Ren,Yuandong Yang
Thermochemical energy storage (TCES) is one of the key technologies facilitating the integration of renewable energy sources and mitigating the climate crisis. Recently, Li4SiO4has been reported to be a promising heat carrier material for TCES applications, owing to its moderate operation temperature and stability. During the synthetic processes, the properties of the Si source used directly influence the performance of derived Li4SiO4materials; however, the internal relations and effects are not yet clear. Hence, in this work, six kinds of SiO2sources with different phases, morphology, particle size, and surface area were selected to synthesize a Li4SiO4-based TCES heat carrier. The physicochemical properties of the SiO2and the corresponding derived Li4SiO4were characterized, and the comprehensive performance (e.g., heat storage/releasing capacity, rate, and cyclic stability) of the Li4SiO4samples was systematically tested. It was found that the silica microspheres (SPs), which possess an amorphous phase, uniform micro-scale structure, and small particle size, could generate Li4SiO4TCES materials with a highest initial capacity of 777.7 kJ/kg at 720 °C/900 °C under pure CO2. As a result, the SP-L showed an excellent cumulative heat storage amount of 5.84 MJ/kg within 10 heat-releasing/storage cycles, which was nearly 1.5 times greater than the value of Li4SiO4derived from commonly used silicon dioxide. Furthermore, the effects of the utilized Si source on the performance of as-prepared Li4SiO4and corresponding mechanisms were discussed, which offers guidance for the future selection of Si sources to produce high-performance Li4SiO4-based TCES heat carriers.
研究领域:
材料科学
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能源存储技术
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
·
2019
·Vol. 2020
·期 3
·318-326
·
IF 2.578
Mingjian Luo,Mingxu Liu,Yadong Fu,Wenxin Chen,Baohui Wang,Guoliang Mao
Graphical Three-stage SAPO-34s have higher purity, smaller crystal size, more acidic sites, longer catalytic lifetime and better olefin selectivity. The crystallization mechanism and the relationship between properties and performance are discussed. Acidity and 2–4 nm mesopores have little effect on MTO performance, which mainly depends on the size and dispersity of the crystallites and the purity of SAPO-34. SAPO-34 zeolites were synthesized by one-, two-, and three-stage crystallization processes with fumed silica (FS), acidic silica sol (AS), basic silica sol (BS) and tetraethoxysilane (TEOS) as silicon sources. Properties of samples were characterized by XRD, SEM, EDX, N 2 -adsorption/desorption, NH 3 -TPD and 29 Si NMR. In contrast with one- and two-stage processes, the three-stage one favors the formation of SAPO-34s with higher purity, higher Si/Al ratio, smaller crystallite/crystal size, better dispersion and more acidic sites. Crystallization mechanism was proposed. It is supposed that three-stage process favors the formation of high supersaturated SBUs (secondary building units) and CBUs (composite building units) before nucleation. Thus massive nuclei are formed during nucleation and well-dispersed small size SAPO-34 crystals are formed in three-stage process. Three-stage SAPO-34s are longer catalytic lifetime and better olefin selectivity in MTO process. TEOS-3 has the best MTO performance. It was found that acidity of sample and mesopores in 2–4 nm range have little effect on the MTO performance of SAPO-34. Catalytic lifetime and olefin selectivity are mainly depending on the size of crystallites, the dispersity of crystallites, and the purity of SAPO-34.
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
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2016
·
IF 1.207
Fang Jin,Xianqiao Wang,Tieliang Liu,Linbo Xiao,Ming Yuan,Yangchun Fan
A new effective process to improve the utilization of industrial fluorosilicic acid of phosphate fertilizer by-product has been investigated to comprehensive application of the silicon and fluorine source. Two-step ammoniation was applied to recover high-quality silica. The recovered silica can be used to hydrothermal synthesize ZSM-5 zeolite without impurity phase contamination, which was confirmed by XRD, TG, SEM, BET and EDS characteristic techniques. It was found that with the increase of SiO 2 /Al 2 O 3 ratio and the extension of reaction time, the crystal type transform from the orthorhombic to the monoclinic phase. The impurity fluorine content of the recovered SiO 2 from H 2 SiF 6 has great influence on the hydrothermal process for ZSM-5 crystal structure formation. Moreover, the increase of fluorine ions content in the hydrothermal process can control the crystal morphology and size of synthesized ZSM-5. Catalytic properties of synthesized HZSM-5 with different SiO 2 /Al 2 O 3 ratio in transalkylation of toluene and 1,2,4-trimethylbenzene show good and stable catalytic performance. The ZSM-5 synthesized with recovered silica source exhibits similar catalyst life as the performance of small particle size HZSM-5, because the ZSM-5 synthesized with the silica source from industrial hexafluorosilicic acid prefers a thin disk crystal along the b axis direction, which shortens the diffusion distance of generated products.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2024
·
IF 4.8
Jialin Ma,Xinrui Du,Mingxiang Wu,Haoyang Geng,Yonghao Wu,Mingxuan Wang,Qiule Zhang,Meijun Ji,Yanfeng Zhang
Zeolite DDR is a small pore zeolite with high application potential in catalysis, adsorption and membrane separation . However, its application is greatly limited by lengthy synthesis time. Various approaches, such as fast heating, reactive raw silica source, special mineralizing agent, seeding, and high synthesis temperature were combined to accelerate crystallization kinetics . The obtained DDR samples were systematically characterized by XRD , SEM, NMR and nitrogen adsorption-desorption. The fastest synthesis was realized by combining microwave radiation , and active (NH 4 ) 2 SiF 6 as silica source, in which high quality DDR zeolite with high yield was obtained in only 5 min. Moreover, replacing toxic (NH 4 ) 2 SiF 6 with safe silica sol led to improved process environment-friendliness and longer synthesis time of 10 min. Finally, replacing expensive microwave heating with economical oil-bath heating resulted into efficient synthesis of zeolite DDR in only 15 min, which would facilitate its commercial applications in adsorption, catalysis and membrane separation.
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
MATERIALS CHEMISTRY AND PHYSICS
·
2021
·
IF 4.094
Shengqiang Zhou,Lipeng Zhou,Yunlai Su,Xiaomei Yang,Hao He
Sn-Beta zeolite is a promising heterogeneous Lewis acid catalyst. Hydrothermal synthesis of Sn-Beta(TEOS) using tetraethyl orthosilicate (TEOS) as silica source is a classical method. However, the hydrolysis of TEOS generates considerable ethanol, which is unfavorable for scalable production of Sn-Beta. Herein, cheap fumed silica and silica sol were used as Si sources to synthesize Sn-Beta and compared with that synthesized from TEOS . The crystalline phase, morphology, physicochemical properties, and the state of Sn were characterized. It was found that Sn-Beta can be successfully prepared with fumed silica and silica sol as well as TEOS as silica source. Sn was introduced into the framework of these samples. Sn-Beta synthesized from fumed silica (Sn-Beta(FS)) and silica sol (Sn-Beta(Sol)) had similar crystallization behavior and full crystallization time as well as morphology, crystal size with that from TEOS. Sn-Beta(Sol) has less silanols and lowest ratio of open/closed tin site among these samples. It exhibited higher catalytic activity for the conversion of glucose to methyl lactate and lower catalytic activity for the isomerization of glucose as compared with the other two samples. Sn-Beta(FS) showed similar catalytic performance in the studied reactions with Sn-Beta(TEOS).
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
JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Na Zhang,Qiang Li,Chunhui Li,Zhen Li,Li Zhao,Xiaotai Zhang,Yi Wang,Zhenghua Li,Xianghua Dou,Wanling Cui,Saisai Li
In this report, a highly ordered mesostructured flexible silica-based nanofiltration membrane is fabricated using tetraethyl orthosilicate (TEOS) as a silica source and Pluronic F127 copolymer as a structure directing agent , and hydrolyzed polyacrylonitrile ultrafiltration membrane as a substrate by an evaporation induced self-assembly approach. The results show the fabricated silica/F127 (SF) composite membrane possesses ordered mesostructures with different space groups depending on the mass ratios of TEOS/F127. The membrane is negatively charged with an isoelectric point at pH 2.9, and it also has a very hydrophilic surface. The pure water permeability of the membrane is 32 Lm −2 h −1 bar −1 . The membrane also has high rejections to methyl blue (100%) and multivalent salts ( > 95%), and moderate rejection to divalent salt (78.5% for Na 2 SO 4 ). The ordering of the mesostructure enhances the membrane compactness, favoring the improvement of the separation performance. Additionally, the membrane possesses satisfactory resistances to humic acid (HA) and bull serum albumin (BSA) fouling, and bacteria adhesion due to the smooth and hydrophilic surface. Additionally, the salt rejection is stable in 0.5 M HCl for 11 h and/or active chlorine solution (pH = 5) with 9000 ppm·h chlorination strength accompanied by an obvious increase in permeate flux. The membrane also exhibits satisfactory performance stability in a long-term (168 h) running.
研究领域:
材料科学
·
环境工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Water Process Engineering
·
2025
·
IF 6.7
Lei Xu,Kangwei Li,Yijia Xu,Song He
This paper reports a novel flexible silica aerogel prepared under ambient pressure using a multi-silica source precursor system. Compared with the single-silica-source system, the new aerogel exhibits excellent flexibility and can be bent up to 180° and compressed to 75 % of its original size without destroying its structure. It shows high adsorption capacity for a wide range of organic solvents, in particular for methylene chloride with an adsorption capacity of 13.7 g/g. In addition, the water contact angle of this aerogel was as high as 141°. The specimens were thoroughly characterised and tested to explore their physicochemical properties. The pore structure was analysed in detail using mercuric pressure and gas adsorption methods, revealing the mechanism behind the high adsorption of organic solvents. These excellent properties make this aerogel have significant potential for application in oil-water separation. Both gravity-assisted filtration and peristaltic pump-assisted filtration can be used for oil-water separation.
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
MATERIALS LETTERS
·
2025
·
IF 2.7
Feng Ye,Shuanshi Fan,Yanhong Wang,Xuemei Lang,Yihui Lv,Weibo Chen,Gang Li
The facile synthesis of hierarchical ZSM-5 zeolites without mesoporogens is highly desirable for industrial applications. In this study, hierarchical ZSM-5 zeolites with abundant mesopores and a nearly single-crystalline structure were rapidly synthesized in a mesoporogen-free system. Under conventional heating, the synthesis time was significantly reduced to just 15 min, significantly improving production efficiency. The key to this ultrafast process was the use of a tubular reactor, combined with the strategic selection of silicon and aluminum sources.
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
MICROPOROUS AND MESOPOROUS MATERIALS
·
2017
·
IF 3.615
Yueyang Liu,Ming Zhao,Linjuan Cheng,Jianhua Yang,Liping Liu,Jinqu Wang,Dehong Yin,Jinming Lu,Yan Zhang
A facile one-pot method through controlled nucleation and release of reactive nutrient species by using bulk silicon dioxide as the Si source and seeds as liberated nuclei was reported for the fabrication of hierarchical ZSM-5 zeolites . This ZSM-5 aggregation (ZSM-5-B) was hierarchically constructed by many flaky ZSM-5 crystals. High methane conversion, high selectivity of aromatics and excellent anti-coking stability were achieved in the catalytic methane dehydroaromatization reaction (MDA) as a model reaction using the Mo-modified ZSM-5-B catalyst. Structure-properties relevance studies indicated the synergistic integration of the suitable acidity, higher external surface and hierarchical porosity contributed to the largely improved MDA catalytic performance. The work demonstrates a much simpler and more economical route for practical application of hierarchical zeolite.
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
Catalysts
·
2018
·Vol. 9
·期 1
·13
·
IF 3.465
Jianguang Zhang,Xiangping Li,Juping Liu,Chuanbin Wang
In this paper, a comparative study of MFI zeolite derived from different silica sources is presented. Dry gel conversion (DGC) method is used to synthesize silicalite-1 and ZSM-5 with MFI structure. Two kinds of silica sources with different particle sizes are used during the synthesis of MFI zeolite. The as-prepared samples were characterized by X-ray diffraction (XRD), N2-sorption, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and X-ray fluorescence spectrometer (XRF). From the characterization results, it could be seen that the high-quality coffin-like silicalite-1 was synthesized using silica sphere with particle size of 300 nm as silica source, with crystallization time being shortened to 2 h. The schematic diagram of silicalite-1 formation using silica sources with different particle sizes is summarized. ZSM-5 was obtained by adding Al atoms to raw materials during the synthesis of MFI zeolite. The performance of aqueous phase eugenol hydrodeoxygenation over Pd/C-ZSM-5 catalyst is evaluated.Keywords:dry gel conversion;MFI zeolite;particle sizes;silica sources;hydrodeoxygenation
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）