Journal of Materials Chemistry A
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2021
·Vol. 9
·期 27
·15238-15245
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IF 12.732
Linying Wang,Dali Zhu,Juan Wang,Wenhao Cui,Jingfeng Han,Bing Li,Dong Fan,Peng Tian,Zhongmin Liu
An X-ray amorphous material with a CHA-like structure, named embryonic CHA zeolite, has been designed and employed for the synthesis of SSZ-13, which leads to ultra-fast crystallization (1.5–12 h), wide product SiO2/Al2O3 ratio (SAR = 22–100) and high yield (82.8–92.9%). The usage of N,N,N-trimethyl-1-adamantammonium hydroxide (TMAdaOH) for the synthesis can be controlled at unprecedentedly low amounts (TMAdaOH/SiO2 = 0.035–0.050). Characterization results reveal that the embryonic zeolite has a small particle size of 10–20 nm, large micro/mesopore volume and abundant double 6-ring units (subunits of the CHA structure). It provides ample active surface and subunits for the formation of the CHA structure and promotes the fast synthesis of SSZ-13 with a wide phase region. The resultant material (SAR = 23.2), after Cu2+ exchange, exhibits superior NH3-SCR activity and extraordinary hydrothermal stability (steaming at 800 °C for 16 h), implying its promising application for NOx removal. In addition, high-silica SSZ-13 shows good catalytic performance for the MTO reaction. It is anticipated that the embryonic zeolite-assisted strategy will benefit the synthesis of more industrially important zeolites.
研究领域:
材料科学
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催化化学
✓ 已验证
DOI
高影响因子
MOLECULES
·
2024
·Vol. 29
·期 9
·2037
·
IF 4.2
Zhaohui Liu,Min Mao,Ruixue Yangcheng,Shuang Lv
Small-pore zeolites catalyze the methanol-to-olefins (MTO) reaction via a dual-cycle mechanism, encompassing both olefin- and aromatic-based cycles. Zeolite topology is crucial in determining both the catalytic pathway and the product selectivity of the MTO reaction. Herein, we investigate the mechanistic influence of MCM-35 zeolite on the MTO process. The structural properties of the as-synthesized MCM-35 catalyst, including its confined cages (6.19 Å), were characterized, confirming them as the catalytic centers. Then, the MTO reactions were systematically performed and investigated over a MCM-35 catalyst. Feeding pure methanol to the reactor yielded minimal MTO activity despite the formation of some aromatic species within the zeolite. The results suggest that the aromatic-based cycle is entirely suppressed in MCM-35, preventing the simultaneous occurrence of the olefin-based cycle. However, cofeeding a small amount of propene in methanol can obviously enhance the methanol conversion under the same studied reaction conditions. Thus, the exclusive operation of the olefin-based cycle in the MTO reaction, independent of the aromatic-based cycle, was demonstrated in MCM-35 zeolite.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
·
2020
·Vol. 2020
·期 22
·2170-2176
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IF 2.529
Xueshuai Chen,Rongli Jiang,Zihan Zhou,Xingwen Wang
Graphical SAPO-34 zeolite was successfully synthesized from laponite as the single Si source. Laponite itself contains Li and Mg atoms, which were subsequently introduced into the structure of SAPO-34 via depolymerization-reorganization of laponite. Metal incorporation can reduce the amount of stronger acid sites and enhance the catalytic performance in the MTO reaction. In this work, SAPO-34 zeolite with high catalytic activity was successfully synthesized by hydrothermal method from laponite as the single Si source. Compared with the traditional method of synthesizing zeolites from clay, the laponite after swelling can be directly used in the synthesis process of zeolite. The crystallization behavior of SAPO-34 synthesized from laponite was investigated by XRD, FTIR, N 2 adsorption–desorption, SEM-EDX, ICP-MS, and DR-UV/Vis. The process can be summarized as follows: the Si and Mg elements were produced by the depolymerization of laponite, then the primary building units of SAPO-34 zeolite were formed under hydrothermal conditions; finally, the crystal nucleus began to form, and crystallization was triggered. Compared with the conventional SAPO-34 synthesized from TEOS, the SAPO-34 synthesized from laponite exhibited higher selectivity to light olefins and longer lifetime, which can be attributed to the suitable strength of acidity. This work points to a straightforward route to the synthesis of SAPO-34 from laponite.
研究领域:
材料科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2018
·Vol. 6
·期 18
·8705-8711
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IF 9.931
Hao Xu,Qinming Wu,Yueying Chu,Jingang Jiang,Ling Zhang,Shuxiang Pan,Changsheng Zhang,Longfeng Zhu,Feng Deng,Xiangju Meng,Stefan Maurer,Robert McGuire,Andrei-Nicolae Parvulescu,Ulrich Müller,Feng-Shou Xiao
2,6-methyl-N-methylpyridinium, as a novel organic template, is employed for the synthesis of RTH aluminosilicate zeolite with a SiO2/Al2O3 ratio of 17.6. The amount of 2,6-methyl-N-methylpyridinium template, the Na2O/SiO2 ratio, the SiO2/Al2O3 ratio, and the H2O/SiO2 ratio in the starting gel significantly influence the crystallization of RTH zeolite. Several analytical methods such as XRD, SEM, N2 sorption, TG-DTA, DRIFT and NMR were employed for the characterisation of the obtained RTH zeolites and to understand the crystallization process with the new template. Very interestingly, the crystallization of RTH zeolite with the new template takes a very short time (12 h at 130 °C and 50 min at 240 °C) compared with conventional RTH zeolite synthesis reported in the literature (72 h at 130 °C). Theoretical calculations show that this novel organic template has lower interaction energies for zeolite cage space filling than those of the organic templates previously reported in the literature, which lead to stronger structural directing. Kinetic results show that the activation energy of this novel organic template is much lower than that of the traditional one. Catalytic tests show that copper exchanged RTH zeolite (Cu-RTH) exhibits good catalytic properties in the NH3-SCR reaction and the H-RTH zeolite catalyst has excellent selectivities for ethylene and propylene in MTO reactions.
研究领域:
催化材料
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化学工程
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 53
·47864-47872
·
IF 3.289
Chan Wang,Miao Yang,Wenna Zhang,Xiong Su,Shutao Xu,Peng Tian,Zhongmin Liu
With the aid of self-designed organophosphorous surfactant [2-(diethoxylphosphono)propyl]hexadecyldimethylammonium bromide (DPHAB), SAPO-34s with various special morphologies have been hydrothermally synthesized by using tetraethylammonium hydroxide (TEAOH), diethylamine (DEA) and triethylamine (TEA) as templates, respectively. The synthesized SAPO-34s were well characterized by XRD, XRF, SEM, N2 adsorption–desorption, solid state NMR and NH3-TPD measurements. The status of DPHAB was also investigated by using FT-IR, 13C NMR, TG–DTA and 31P NMR measurements as well as density functional theory calculations. It is found that the addition of DPHAB changes the crystal morphology dramatically and the aggregation degree of the crystals increases with the rising DPHAB/H3PO4 ratio. Moreover, microporous templates play an important role in the synthesis of mesoporous SAPO-34. TEAOH, which has the strongest interaction energy with the CHA framework among the investigated templates, shows the best cooperating ability with an organophosphorous surfactant to direct the formation of nanosized and mesoporous SAPO-34. The prepared SAPO-34s showed improved catalytic properties in the methanol-to-olefins (MTO) reaction.
研究领域:
化学工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2023
·
IF 5.5
Jinbo Zhu,Xu Chen,Xiangge Sang,Gang Yang
SAPO-34 catalysts with high selectivity for light olefins were first synthesized via the introduction of phosphomolybdic acid (HPMo) and AlPO 4 -5 zeolite into the initial gel. The physical and chemical characteristics of the synthesized catalysts were determined by a series of techniques and the catalytic performance of the modified composite zeolites for the methanol-to-olefin (MTO) reaction was investigated. The results indicated that HPMo-modified SAPO-34 was featured with more Brønsted acid sites, more mesopores, and a smaller crystal size, thereby demonstrating superior catalytic performance. The further combination with AlPO 4 -5 (16.7 wt%) prolonged the lifetime of the HPMo-modified SAPO-34, which is thought in this paper related to its 12-ring straight channel (0.7–0.8 nm) and the absence of any Brønsted acid sites. The MTO tests showed that the light olefins selectivity for the modified composite zeolites reached 95.1 %, while the catalyst lifetime remained at 445 min
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CRYSTENGCOMM
·
2021
·Vol. 23
·期 15
·2793-2800
·
IF 3.545
Xueshuai Chen,Rongli Jiang,Yu Gao,Zihan Zhou,Xingwen Wang
In this work, nano-ZSM-5 zeolite with superior catalytic properties was synthesized from LAPONITE® as one of the Si sources by a dry gel conversion (DGC) method, and its crystallization mechanism was investigated as well. The properties of ZSM-5(Z-L) synthesized from LAPONITE® as one of the Si sources and ZSM-5(Z-T) synthesized from tetraethylorthosilicate (TEOS) as a single Si source have been compared. The results show that LAPONITE® is an important factor for the formation of nanocrystals with high crystallinity. It can not only act as the Mg and Si source for the zeolite synthesis but also exert a “confined space” effect to control ZSM-5 crystal growth. The Z-L sample with nanosized crystals can shorten the reactant and product diffusion path length, which seriously improves diffusion efficiency and results in longer catalytic stability. This work provides a novel and efficient route for synthesis of nano-ZSM-5 zeolite.
研究领域:
材料科学
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化学工程
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催化
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2015
·Vol. 3
·期 10
·5608-5616
·
IF 7.443
Chan Wang,Miao Yang,Peng Tian,Shutao Xu,Yue Yang,Dehua Wang,Yangyang Yuan,Zhongmin Liu
A spherical self-assembly of SAPO-34 nanosheets was hydrothermally synthesized by using a quaternary ammonium-type organosilane surfactant [3-(trimethoxysilyl)propyl]octadecyldimethylammonium chloride (TPOAC) as the mesoporogen and a part of the silica source, and diethylamine (DEA) as the microporous template. The prepared materials were well characterized by XRD, XRF, SEM, TEM, N2 adsorption–desorption, NH3-TPD, NH3-adsorbed IR and pyridine-adsorbed IR measurements. It revealed that the morphologies, compositions and acidity of the SAPO-34 products changed significantly with the increased TPOAC/TEOS ratio, showing that the TPOAC/TEOS ratio had a significant impact on the crystallization process of SAPO-34. Solid state 13C, 29Si NMR and TG-DTA analyses were further conducted to investigate the status of TPOAC in the final products. A possible crystallization process involving TPOAC was proposed. The catalytic performances of the synthesized SAPO-34s were evaluated using the MTO reaction. The optimal SAPO-34 nanosheet assemblies with a hierarchical porous structure displayed a remarkably enhanced catalytic lifetime and high yields of light olefins.
研究领域:
材料科学
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化学工程
·
催化
·
无机化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）