Micro & Nano Letters
·
2023
·Vol. 19
·期 1
·e12182
·
IF 1.3
Weilin Jia,Suyang Wang,Yingying Deng,Jie Shen,Ping Zhao,Zepeng Wang,Jiaojing Shao,Yuanyu Wang,Qi Sun
A simple and effective method was reported for the rapid synthesis of zeolite X from kaolin by adding a template agent. The results of X-ray diffraction confirm the good crystallinity of the synthesized X-zeolite with lamellar structure. Transmission electron microscopy images clearly demonstrate the lamellar structure of the synthesized X-zeolite. The corresponding selective electron diffraction pattern suggests that the crystal structure of X-type zeolite is octahedral. The co-existence and uniform distribution of Si, Al, O, and Na in the layered structure of the synthesized X-type zeolite are detected by element mapping. In addition, N 2 adsorption–desorption measurement indicates that the specific surface area of the lamellar zeolite X is 153.4625 m 2 g −1 . The micropore surface area is 148.8374 m 2 g −1 , and the micropore volume is 0.073377 m 2 g −1 . After exploring the influence of different temperatures on the adsorption of carbon dioxide, the research shows that two-dimensional zeolite X has the best adsorption capacity for carbon dioxide. The adsorption and separation performance of CO 2 /CH 4 was investigated. The study showed that the adsorption and separation coefficient of two-dimensional zeolite X was the highest.
研究领域:
材料科学
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环境科学
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DOI
高影响因子
Nanomaterials
·
2025
·Vol. 15
·期 11
·797
·
IF 4.3
Mingbo Guo,Yijun Wang,Lei Zhang,Junran Lu,Chang Gong,Wanning Zhang,Yuxi Fang,Xinyuan Zhu,Shunai Che
Size restrictions pose increasing challenges to the acoustic performance of microspeakers in portable devices as the size of such devices, and thus the back volume of microspeakers, continues to shrink. Filling the back volume with porous materials, such as zeolites, has been proved to be an effective strategy for improving acoustic performance. In this work, hierarchically structured ZSM-5 zeolites with abundant mesopores were synthesized via the traditional hydrothermal method by adjusting the SiO2/Al2O3ratios (SAR), and their pore structures and morphologies were systematically investigated. Their acoustic enhancement performance was evaluated using a commercial microspeaker. Based on their acoustic properties, the influence of pore structure on acoustic performance was further studied. The ZSM-5 zeolite sample with an SAR of 614, which exhibited the maximum mesopore volume, demonstrated exceptional acoustic enhancement performance with a resonance offset of 199.53 Hz and an enhanced sound pressure level of 4.74 dB at 500 Hz. The presence of mesopores significantly facilitates diffusion within the zeolite crystals, enabling air molecules to access more micropores for efficient sorption–desorption processes during diaphragm vibration in microspeakers. Furthermore, supermicropores were found to contribute to improved performance by adsorbing air molecules during diaphragm vibration, complementing the role of micropores.
研究领域:
材料科学
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声学工程
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DOI
PubMed
高影响因子
FUEL
·
2019
·
IF 5.128
Han Jiang,Bin Guan,He Lin,Zhen Huang
This study focuses on investigating the influence of Si/Al ratio on the performance of hydrothermally aged Cu/SSZ-13 catalysts prepared by in situ hydrothermal synthesis method. It was found that NH 3 -SCR performance and hydrothermal stability of Cu/SSZ-13 decreased with increasing Si/Al ratio. Fresh and hydrothermally aged Cu/SSZ-13 with Si/Al ratio of 6.5 showed the best SCR activity and N 2 selectivity in a broad temperature of 200–500 °C, in which more than 90% NO x was reduced with superior N 2 selectivity above 95%. The effect of Si/Al ratio on the properties of the physicochemical structure, the change of acidity intensity, and Cu species migration or transformation of the fresh and aged Cu/SSZ-13 catalysts were comprehensively characterized by NH 3 -TPO, NH 3 -TPD, H 2 -TPR, N 2 physisorption, XRD, ICP-AES, and XPS. The increase of the surface CuO species, the decrease of the amount of Cu 2+ in active sites, the chemisorption NH 3 species, the specific surface area, the total pore volume, and the increase of average pore diameter, may be the main reasons for performance deterioration over high-Si/Al-ratio catalysts after hydrothermal aging. Furthermore, in situ DRIFTS indicate that, with the increasing Si/Al ratio, the zeolitic structure was easy to collapse, and that the surface acid sites, the active copper species, as well as the adsorbed surface nitrate, decreased after hydrothermally aged. After hydrothermal aging, the amount of isolated Cu 2+ decreased, and more CuO species were aggregated, mainly coming from the conversion of the unstable isolated Cu 2+ species in D6R or CHA cages. The decrease of isolated Cu 2+ and CuO species aggregation were significant in Cu/SSZ-13 with high Si/Al ratios. The CuO leaded to the instability of the SSZ-13 skeleton structure and NH 3 oxidation promotion, resulting in catalysts deactivation.
研究领域:
催化化学
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环境科学
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产品关联
DOI
高影响因子
Molecular Catalysis
·
2024
·
IF 3.9
Fuxin Liang,Yulin Wei,Yuhang Du,Fan Yang,Zhe Pang,Haochen Dang,Junyan Wu,Sai Huang,Honglei Wang,Qinggang Li,Chao Wu,Zhi Wang,Guopu Shi
In drug synthesis, ethyl nicotinate hydrogenation is commonly performed to prepare ethyl 3-piperidine-carboxylate. For this hydrogenation, it is crucial to explore a catalyst with high catalytic activity and selectivity to form the desired product. To this end, a series of Pd/Al 2 O 3 -SiO 2 catalysts with various SiO 2 contents were prepared via coprecipitation on the surface of foam ceramics. We investigated the effect of SiO 2 incorporation on the physical and chemical properties of the catalysts, such as specific surface area, pore structure, number of acidic sites, metal–support interactions, and catalytic activity. The addition of Si was found to weaken the metal–support interactions, facilitate the reduction of PdO, provide more metal sites, and increase the catalytic efficiency of catalyst. The effects of temperature and pressure on the hydrogenation reaction were also investigated, and under optimal reaction conditions, product yields of up to 85.53 % were achieved. This study offers a novel approach for the catalytic hydrogenation of ethyl nicotinate using carrier-modified metal–acid catalysts.
研究领域:
催化化学
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药物合成
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材料科学
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DOI
高影响因子
GREEN CHEMISTRY
·
2020
·Vol. 22
·期 5
·1630-1638
·
IF 9.48
Bin Zhang,Mark Douthwaite,Qiang Liu,Chao Zhang,Qifan Wu,Ruhui Shi,Peixuan Wu,Ke Liu,Zhuangqing Wang,Weiwei Lin,Haiyang Cheng,Ding Ma,Fengyu Zhao,Graham J. Hutchings
A novel method for the synthesis of MFI zeolites has been developed, which does not require any crystal seeds or solvent. The adaptability of this method was also evidenced; a series of ZSM-5 zeolites with differing Si/Al ratios (18∼∞) were synthesized, which to date, has been a challenge in the field of solvent-free synthesis. The materials were probed by in situ DRIFTS and 2D 27Al–19F HETCOR NMR spectroscopy, the results from which indicated that fluorine-containing species play a crucial role in the crystallization of ZSM-5. During the crystallization process F− anions coordinate with Al3+ cations, resulting in the formation of 6-coordinated “F–Al–O–Si” species. It is these intermediate species which drive the formation of tetrahedral [AlO4]− units in the zeolitic framework. The effectiveness of these materials as catalyst supports was subsequently assessed in the hydrogenation of levulinic acid and glucose, which exhibited a comparable performance to commercial ZSM-5. The simple, efficient and low-cost method presented herein provides an alternative approach for the green scaled-up synthesis of zeolites.
研究领域:
材料科学
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催化化学
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产品关联
DOI
高影响因子
ACS Omega
·
2020
·
IF 2.87
Hong Hai Wang,Zhi Ling Liu,Yu Cong Song,Hao Li
Hydrodeoxygenation (HDO) is one of the effective methods to upgrade biomass pyrolysis oil, but the development of a low-cost, high-performance HDO catalyst still faces enormous challenges. In this work, a facile and eco-friendly approach is developed to synthesize the Ni2P@hierarchical HZSM-5 catalyst. Structure and acidity of the catalyst can be controlled by simply adjusting the proportions of ammonia solution and the silicon to aluminum ratio, which are closely related to the performance of the catalyst. Experimental results reveal that the Ni2P@hierarchical HZSM-5 catalyst with Si/Al = 85 under NH3·H2O/Ni = 14 exhibits the highest activity of 98% guaiacol conversion, along with a 78.8% yield of cyclohexane (reaction conditions: 300 °C, 3 MPa H2). In addition, the guaiacol reaction network is provided.
研究领域:
催化化学
·
能源化学
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产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2013
·
IF 3.365
Danhua Yuan,Shutao Xu,Mozhi Zhang,Yingxu Wei,Xinglong Dong,Yanli He,Shuliang Xu,Zhongmin Liu,Yunpeng Xu
ZSM-2 nanorods with crystal size around 50 nm were successfully synthesized at ambient temperature (30 °C). The crystallization process of ZSM-2 zeolite under ambient temperature was studied and discussed according to the measurement of crystallization kinetic curve, and characterizations with multiple techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), low-temperature N 2 adsorption/desorption analysis, thermogravimetry analysis (TG) and nuclear magnetic resonance (NMR) etc. The ZSM-2 zeolite synthesized at ambient temperature presented different crystal morphologies and large specific area as compared with the sample synthesized at high temperature (100 °C). Furthermore, 29 Si MAS-NMR showed that the nanoscale ZSM-2 obtained by ambient synthesis contained more EMT phase and lower Si/Al ratio than that of micrometer-sized ZSM-2 crystals obtained at 100 °C. More interestingly, NMR and low-temperature N 2 adsorption/desorption characterizations revealed that the local environment of Al did not change much while that of Si did change a lot during the ambient crystallization process, and the micropore area increased rapidly while the micropore size distributions of the samples changed little with increasing crystallization time.
研究领域:
材料科学
·
化学工程
·
物理化学
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产品关联
DOI
高影响因子
Nanomaterials
·
2022
·Vol. 12
·期 11
·1803
·
IF 5.719
Tinglong Yang,Mengqin Yao,Jun Ma,Peng Chen,Tianxiang Zhao,Chunliang Yang,Fei Liu,Jianxin Cao
In this paper, the molecular sieve NaZSM-5 was modified with zirconium dioxide (ZrO2) by a hydrothermal coating process and other methods. By comparing the effects of the crystal phase structure of ZrO2and the compositing method on the physicochemical properties and catalytic performance of the obtained composites, the structure–performance relationship of these composite catalysts was revealed. The results indicate that in the hydrothermal system used for the preparation of NaZSM-5, Zr4+is more likely to dissolve from m-ZrO2than from t-ZrO2, which can subsequently enter the molecular sieve, causing a greater degree of desiliconization of the framework. The larger specific surface area (360 m2/g) and pore volume (0.52 cm3/g) of the m-ZrO2/NaZSM-5 composite catalyst increase the exposure of its abundant acidic (0.078 mmol/g) and basic (0.081 mmol/g) active centers compared with other composites. Therefore, this catalyst exhibits a shorter induction period and better catalytic performance. Furthermore, compared with the impregnation method and mechanochemical method, the hydrothermal coating method produces a greater variety of acid–base active centers in the composite catalyst due to the hydrothermal modifying effect.Keywords:ZrO2crystalline phase;NaZSM-5 modification;hydrothermal coating strategy;Si/Al ratio;methanol thiolation
研究领域:
催化化学
·
材料科学
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产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2018
·
IF 3.649
Baoyu Liu,Zhipeng Chen,Jiajin Huang,Huiyong Chen,Yanxiong Fang
The MFI zeolites with nanosheet assemblies morphology were prepared by a seed-assisted strategy using specially designed bolaform surfactant [C 6 H 13 -N + (CH 3 ) 2 -C 6 H 12 -N + (CH 3 ) 2 -(CH 2 ) 12 -O-(p-C 6 H 4 ) 2 -O-(CH 2 ) 12 -N + (CH 3 ) 2 -C 6 H 12 -N + (CH 3 ) 2 -C 6 H 13 ] [Br − ] 4 (C 6-12-diphe ) as a structure-directing agent. The MFI zeolite nanosheet assemblies were composed of MFI nanosheets with randomly organized structure, exhibiting a narrow mesopore distribution. By tuning the Si/Al ratios of MFI zeolite nanosheet assemblies from 60 to 10, the morphology of resultant zeolites changed from nanosheet stacks to house-of-cards-like structures, and to nanosponges. In addition, the porosity and Brønsted acid/Lewis acid ratio exhibited a parabola-type dependence on the Si/Al ratios of obtained zeolites, indicating that meso-/microporosity and acidity of MFI nanosheet assemblies can be systematically tailored by changing the constituents of zeolites. Catalytic performance of MFI zeolite nanosheet assemblies was investigated in the benzylation of benzyl alcohol with mesitylene. The results revealed that MFI zeolite nanosheet assemblies exhibited extraordinary catalytic activity compared to conventional ZSM-5 zeolite. The conversion of benzyl alcohol and selectivity (1,3,5-trimethyl-2-benzylbenzene vs dibenzyl ether) of zeolite catalysts were linearly dependent on the Brønsted acid/Lewis acid ratio, and they exhibited a parabola-type dependence on the S ext /S BET , indicating that a balance between acidity and porosity of zeolites can be realized to modulate the catalytic properties of MFI zeolite nanosheet assemblies guided by C 6-12-diphe .
研究领域:
材料科学
·
催化化学
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产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2022
·
IF 6.562
Yifan Zheng,Hongxin Ding,Enhui Xing,Jinghua Zhou,Yibin Luo,Jichang Liu,Kake Zhu
ZSM-48 is a unidimensional zeolite that is frequently used as acid component of bi-functional hydroisomerization catalyst. As selectivity towards unwanted cracking products increases with retention time of isomerized products inside micropores, shortening their retention time inside the micropores by reducing channel length offers an effective way to improve isomerization selectivity. Direct synthesis of unidimensional zeolitic crystals with reduced channel axis is particularly difficult, since they habitually grow into rod-like shape along their channel direction. Post-synthetic bead-milling is a cost effective, mechanochemical method to decrease crystal size of zeolites from micro meter to nano meter scale, but suffers from amorphization or partial destruction of zeolitic crystals. Consequently, a post-milling recrystallization process is often entailed to remedy the destructed domains, which, nonetheless, readily causes secondary crystal growth and formation of bulky crystals that compromises the effect of bead-milling. Here, we show that porogen-assisted recrystallization can overcome the problem to fabricate channel axis reduced ZSM-48 nanocrystals. The Si/Al ratio is tunable between 30 and 200 and the acidity is largely preserved after recrystallization. The catalytic advantages of the obtained material are demonstrated in catalytic n -heptane hydroisomerization. The obtained ZSM-48 nanocrystal with Si/Al ratio of 100 outperforms the rest samples and shows enhanced isomerization yield (72% vs 62%) with respect to the parent sample. By combined diagnoses of the impact of diffusion length on product selectivity (product shape selectivity) and kinetic studies , selectivities to monomethyl branched isomers (2-methyl hexane and 3-methyl hexane) and small bulky dimethyl branched isomers (2,3- and 2,4-dimethyl pentane) are attributed to product shape selectivity, whereas the formation to bulky dimethyl branched isomers (2,2- and 3,3-dimethyl pentane) is hindered mainly by transition-state shape selectivity. The combined destructive-constructive synthetic protocol and the revelation of the origin of shape-selectivity in n -heptane hydroisomerization are useful for hydroisomerization catalyst design.
研究领域:
催化材料
·
化学工程
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Cheng Wang,Shaozheng Leng,Huidong Guo,Jiale Yu,Wenjie Li,Liyun Cao,Jianfeng Huang
Acid treatment is an effective way to arrange SiO 2 /Al 2 O 3 ratio of natural zeolite . However, limited researches have been done on quantitative regulation of SiO 2 /Al 2 O 3 ratio of natural zeolite . In this paper, an orthogonal test was designed to optimize the acid treated conditions. Acid concentration, treated time and temperature were then employed to quantitatively arrange the SiO 2 /Al 2 O 3 ratio of natural zeolite, respectively. The results showed that the primary and secondary factors of acid treatment were acid treated time, acid concentration and acid treated temperature, respectively. The extent of dealumination of zeolite and its corresponding SiO 2 /Al 2 O 3 ratio of natural zeolite could rise up to 98.4% and 372.7 under the optimized condition for 48 h, 8 M and 70 °C, respectively. Acid concentration, treated time and temperature could effective quantitatively arrange the extent of dealumination of zeolite and SiO 2 /Al 2 O 3 ratio of natural zeolite. The as-prepared acid treated zeolites with different SiO 2 /Al 2 O 3 ratio regulated by acid concentration had higher specific surface area , micropore volume, silanol group content and hydrophobicity than those for the natural zeolite.
研究领域:
材料科学
·
无机化学
·
多孔材料
·
矿物加工
·
表面改性
✓ 已验证
DOI
高影响因子
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
·
2022
·
IF 4.383
Cheng Wang,Jiale Yu,Kai Feng,Huidong Guo,Lipeng Wang
In this study, natural clinoptilolite was treated with NaOH solutions of different concentrations under mild ambient conditions. The composition and structure of the as-prepared samples were characterized, and their performance was assessed in terms of the removal of the heavy metal ions Cd 2+ , Cu 2+ , and Cr 3+ from the aqueous solution. The results showed that the composition, structure, and capability of removal of heavy metal ions of the samples were significantly influenced by the NaOH concentrations. The crystal structure of clinoptilolite remained invariant under a relatively low NaOH concentration (≤0.5 M), began transforming into zeolite Na–P under a medium NaOH concentration (∼1.0 M), and then completely transformed into it under a high NaOH concentration (2.0–4.0 M). The samples treated with NaOH had lower SiO 2 /Al 2 O 3 ratios, and were superior to unmodified natural zeolite in removing the heavy metal ions. This method of treatment with relatively high concentrations of NaOH is a simple and effective way to transform natural clinoptilolite into the zeolite Na-P rich ion exchanger, which is suitable for removing heavy metal ions.
研究领域:
环境科学
·
材料科学
✓ 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）