INORGANIC CHEMISTRY
·
2024
·
IF 4.3
Yu Gu,Zhiqiang Tao,Shujia Zhang,Xiaohui Wang,Hao Yan,Xinmei Liu,Lei Wang,Jun Xu,Hui Shi
Methane–propane coaromatization (MPCA) upgrades two abundant and inexpensive light alkanes into value-added aromatic products. While Ga-loaded MFI zeolites represent by far the most promising catalysts for MPCA reaction, they often contain a sizable portion of Ga species at the external surface of zeolites, which are remote from the Brønsted acid sites (BAS) within MFI pores and thus inefficient for MPCA. Here, we show that Ga can be introduced into MFI pores at fairly high loadings via a simple cocrystallization approach, yielding catalysts possessing well-dispersed Ga sites predominantly residing inside the pores and framework. Adjacency between Ga and BAS within the constraints of MFI channels makes these (Ga, Al)-H-MFI catalysts more active toward methane and propane activation and more selective toward aromatics compared to the Ga/MFI counterparts prepared by impregnation that inevitably leaves a large fraction of Ga at the external surface (i.e., without confinement and few adjacent BAS). Further, the effects of the Si/Al ratio on MPCA performance have been investigated for (Ga, Al)-H-MFI catalysts. Due to the multifold roles of BAS in the overall reaction sequence, an increased BAS concentration generally results in higher propane conversion and productivity of aromatics together with lower net methane conversion and severer coking.
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高影响因子
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
·
2020
·Vol. 20
·期 3
·1520-1529
·
IF 1.134
Deng Senlin,Lv Guojun,Zhai Yi,Yang Zebin,Zhu Yongqiang,Li Haichao,Wang Fumin,Zhang Xubin
Highly active and stable framework Fe-doped ZSM-5 (f-Fe-ZSM-5) zeolites with different Fe contents, which were synthesized using a facile one-pot hydrothermal method, could effectively resolve the loss of iron element during the catalytic degradation of basic dyes. The successful introduction
of Fe species into the framework of ZSM-5 was confirmed by elemental mappings, Fourier transform infrared (FT-IR) spectroscopy and Ultraviolet-visible spectroscopy (UV-vis spectra). The operational parameters, such as Fe content, H2O2 concentration, reaction temperature,
types of dyes as well as the stability of the synthesized samples were extensively evaluated. It was demonstrated that the f-Fe(0.10)-ZSM-5 exhibited an efficient catalytic ability and excellent stability even after seven consecutive runs. The degradation efficiency of f-Fe-ZSM-5 for basic
dyes was higher than that for acid dye. Therefore, f-Fe-ZSM-5 zeolites may present major potential for the treatment of basic dyes waste water without adjusting the initial pH value.
研究领域:
催化
·
环境科学
·
材料科学
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2015
·
IF 7.435
Jian Li,Yanqing Yu,Xiangyu Li,Wei Wang,Gang Yu,Shubo Deng,Jun Huang,Bin Wang,Yujue Wang
A series of gallium-containing MFI zeolites were prepared via impregnation of conventional aluminosilicate ZSM-5 with Ga (Ga/ZSM-5) or hydrothermal synthesis of galloaluminosilicate (Ga–Al–Si) and gallosilicate (Ga–Si) MFI zeolites. These Ga-containing zeolites were then tested as the catalysts for co-feed catalytic fast pyrolysis (CFP) of pine wood and low-density polyethylene (LDPE) mixtures. Compared with conventional ZSM-5 zeolites, the Ga-containing MFI zeolites considerably increased the yields of valuable petrochemicals (monoaromatic hydrocarbons and olefins) and decreased the yields of undesired polyaromatic hydrocarbons and low-value alkanes from the co-feed CFP. In addition, Ga–Al–Si and Ga–Si zeolites generally produced both higher yields and selectivities for valuable petrochemicals (e.g., p -xylene and olefins) than Ga/ZSM-5 in the co-feed CFP. The results indicate that Ga-containing zeolites may be used to improve petrochemical production in co-feed CFP of biomass and plastics, and direct hydrothermal synthesis of Ga–Al–Si and Ga–Si MFI zeolites may provide a more convenient and better alternative to post modification of ZSM-5 with Ga to prepare Ga-containing zeolites for co-feed CFP.
研究领域:
化学工程
·
材料科学
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2022
·
IF 5.876
Guojun Lv,Yan Chen,Xuyang Zou,Jiangzhang Wang,Tao Wang,Fumin Wang,Xubin Zhang
Simultaneous insertion of double heteroatom in the MFI framework generally gives rise to synergistic catalysis effect, however the specific origins for synergistic catalysis is still nebulous. In this study, vanadium-titanium doped MFI zeolite was synthesized via one-pot hydrothermal synthesis with the addition of (NH 4 ) 2 CO 3 and applied as heterogeneous catalyst for the synergistic catalysis of 1-hexene and cyclohexene epoxidation. Simultaneous incorporation of vanadium and titanium induced the partial charge transformation of titanium (Ⅳ) into titanium (Ⅲ), which was verified by EPR and XPS characterizations. UV-Raman and UV–Vis spectra disclosed that partial charge transformation mainly occurred for framework titanium (Ⅳ). In addition, simultaneous insertion of vanadium and titanium gave rise to more Lewis acid sites as well as larger external surface area for VTS(0.15) zeolite in comparison to VS(0.15) and TS(0.15) zeolite. The prepared VTS(0.15) zeolite presented a TOF value of 118.8 h −1 for 1-hexene epoxidation, which is 7.8 folds and 1.3 folds of VS(0.15) and TS(0.15) respectively. Partial charge transformation of framework titanium (Ⅳ) into titanium (Ⅲ), robust Lewis acid sites as large external surface area may induce the synergistic catalysis effect for VTS(0.15) zeolite in the epoxidation reactions. Moreover, the obtained VTS(0.15) zeolite particles showed good reusability for more than five cycles.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2022
·
IF 9.965
Zeyu Jiang,Rui Dong,Mingjiao Tian,Chi He,Yani Wu,Mudi Ma,Shouning Chai
Realizing the simultaneous adsorption and activation of O 2 and reactants over supported noble metal catalysts is crucial for the oxidation of organic hydrocarbons. Herein, we report a facile one-step ethylene glycol reduction method to synthesize difunctional Au(OH)K x sites, which were anchored on a hierarchical hollow MFI support and adopted for acetone decomposition. The alkali ion-associated adjacent surface hydroxyl groups were coordinated with Au nanoparticles , resulting in partially oxidized Au 1+ sites with improved dispersion. The results obtained from exclusive ex situ and in situ experiments illustrated that the proper content of K and hydroxyl groups significantly enhanced the adsorption of surface O 2 and acetone molecules around the Au sites simultaneously, whereas the excess K species inhibited the catalytic performance by blocking the pore structure and decreasing the acidity of catalysts. The Au(OH)K 0.7 /h-MFI catalyst exhibited the highest efficiency for acetone oxidation, over which 1500 ppm acetone can be completely oxidized at just 280 °C with an extremely low activation energy of 32.5 kJ mol −1 . The carbonate species were detected as the main intermediates during acetone decomposition over the difunctional Au(OH)K x sites through a Langmuir − Hinshelwood (L − H) mechanism. This finding paves the way for designing and constructing efficient functional active sites for the complete oxidation of hydrocarbons.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Qing Zhang,Yi Zhai,Fumin Wang,Xubin Zhang,Guojun Lv,Yongkui Liu,Mengyue Li,Mengyao Li
Hierarchical Fe-doped MFI/MCM-41 composites (Fe-HMZs) were one-pot hydrothermal synthesized by partial transformation strategy using conventional CTAB as a dual-functional template. The hierarchical Fe-doped MFI/MCM-41 composites possess ordered mesopores and crystallized MFI structure. The effect of addition amount of NaOH and CTAB as well as the type of the alkali source on the formation of hierarchical Fe-MFI/MCM-41 composites have been investigated in detail. In addition, the temperature-gradient treatment plays the vital roles in the formation of MFI and the possible formation mechanism has been proposed. The obtained hierarchical Fe-HMZ-40 sample exhibits outstanding catalytic performance for phenol hydroxylation and 48% of phenol conversion as well as 89% of dihydroxybenzene selectivity could be achieved, which are ascribed to the more accessible active sites endowed by the significant diffusion ability of ordered mesopores. Compared with Fe-MCM-41 sample, the hydrothermal stability is improved because of the presence of MFI structure.
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ENERGY & FUELS
·
2019
·
IF 3.021
Mingxue Su,Wenzhi Li,Qiaozhi Ma,Song Li,Tao Yang,Xiaomeng Dou
A water-tolerant, basic, and hierarchical MFI zeolite catalyst was synthesized and applied in the aldol condensation reaction between biomass-derived furfural and levulinic acid. The results showed that the addition of poly(diallyl dimethylammonium chloride) significantly affected the textural and acid–base properties of hierarchical zeolite, which subsequently influenced the catalytic performance of hierarchical zeolite. In the aqueous phase, potassium-modified, hierarchical MFI zeolite (K/H-MFI-n) was more active for aldol condensation between furfural and levulinic acid than the potassium-modified, conventional MFI zeolite (K/MFI). This was ascribed to higher basic sites density and improved diffusion limitation of K/H-MFI-n. A 70.6% yield of aldol condensation product was achieved with a complete conversion of furfural at 100 °C for 9 h by K/H-MFI-0.6. However, only 27.4% yield of aldol condensation product with 55.1% furfural conversion was obtained by K/MFI at the same condition. Two major isomeric aldol products, β-furfurylidenelevulinic acid and δ-furfurylidenelevulinic acid (β-FDLA and δ-FDLA), were obtained after acidification. K/H-MFI-n displayed an enhanced selectivity (54.9%) to δ-FDLA, owing to the stronger basicity of K/H-MFI-n. However, K/MFI showed a preferred selectivity to β-FDLA (42.7%), owing to the dominant Lewis acidity. Recyclability research showed that the catalytic performance of potassium-modified, hierarchical MFI zeolite was acceptable after five runs.
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ACS Applied Materials & Interfaces
·
2022
·
IF 10.383
Chao Miao,Shumei Chen,Kaixuan Shang,Lixing Liang,Jing Ouyang
The dry reforming of methane (DRM) is a new potential technology that converts two major greenhouse gases into useful chemical feedstocks. The main challenge faced by this process is maintaining the catalyst with high catalytic activity and long-term stability. Here, a simple and effective preparation route for the synthesis of functional nanomolecular sieve catalysts (NiRuxCZZ5) from kaolinite tailings was developed for dry reforming of methane with CO2. The silica monoliths with flower-like spherical and micropore structures (ZSM-5) were prepared by crystal growth method, and the metal components were loaded by ultrasonic-assisted impregnation method. The NiRu0.5CZZ5 catalyst exhibited excellent catalytic performance (maxmium CO2 and CH4 conversions up to 100 and 95.6%, respectively) and very good stability (up to 100h). The interfacial confinement and the strong support interaction are principally responsible for the excellent catalytic activity of the catalyst. The in situ DRIFTS was used to elucidate the possible carbon conversion steps, and stable surface intermediates were also identified.
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ChemSusChem
·
2019
·Vol. 12
·期 16
·3871-3877
·
IF 7.804
Dan Wu,Xing Yu,Xinqing Chen,Gan Yu,Kun Zhang,Minghuang Qiu,Wenjie Xue,Chengguang Yang,Ziyu Liu,Yuhan Sun
Graphical Stacks on ! H-type MFI zeolite catalysts with a unique stacked structure are synthesized in a one-pot procedure in the presence of NH 4 F with the help of zeolite confinement through a solvent-free route without further ion-exchange procedures. The catalysts display excellent catalytic performance in methanol-to-gasoline reactions. H-type aluminosilicate zeolites are extensively used as solid-acid catalysts and support materials in industrial catalysis. However, the conventional synthesis methods involving hydrothermal syntheses and ion-exchange processes suffer from severe water pollution and toxic gas emissions. Herein, H-type MFI zeolite catalysts with a unique stacked structure were directly synthesized in the presence of NH 4 F and with the help of zeolite confinement through a solvent-free route without further ion-exchange procedures. A range of ex situ and in situ characterization procedures were used to provide evidence of the simultaneous use of pre-made ZSM-5 and NH 4 F as a confined Al source and mineralizer, respectively. The confined zeolite framework of ZSM-5 prevented the formation of AlF x species between NH 4 F and Al atoms, ensuring that the prepared samples had desirable acidic properties. Moreover, the resulting morphology could be controlled by using different silica substrates. The obtained H-type MFI zeolites showed excellent catalytic performance in methanol-to-gasoline reactions owing to their unique structure and directly exposed acidic sites. The developed one-pot strategy provides an alternative method for the facile synthesis of H-type zeolites with defined morphology.
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CRYSTENGCOMM
·
2022
·Vol. 24
·期 14
·2697-2704
·
IF 3.756
Siyu Zhang,Xiaomin Zhang,Lei Dong,Shengjie Zhu,Yangyang Yuan,Lei Xu
In this work, Pt nanoparticles (NPs) were directly encapsulated into MFI-type zeolite (Pt@S-1) via a steam-assisted dry-gel conversion method. The synthesis process included the disaggregation of Pt immobilized SiO2–SH spheres and the in situ crystallization for the synthesis of Pt@S-1. The Pt NPs remained stable during the whole crystallization process and the average size of Pt NPs in the synthesized Pt@S-1 was from 1.54 to 2.34 nm. The highest encapsulation degree of Pt NPs was calculated as 93.8% and decreased slightly to 84.9% with the increase of Pt loading. Owing to the high encapsulation degree of Pt NPs in MFI crystals, the size of Pt NPs after calcination at 800 °C only grew up to 3.19 nm showing significantly high thermal stability. The uniform microporous pores of silicalite-1 zeolite as well as the small size and stable Pt NPs endow the Pt@S-1 catalyst with high activity and stability in the nitrobenzene hydrogenation reaction.
研究领域:
材料科学
·
催化化学
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Inorganic Chemistry Frontiers
·
2025
·
IF 6.4
Hao Wu,Yi Wang,Pingping Wu,Hongchao Fan,Yuanhao Liu,Shuyan Liu,Peng Bai,Zi-Feng Yan,Svetlana Mintova
Addressing the global challenge of waste plastic management, catalytic cracking utilizing zeolite catalysts offers a sustainable approach for converting plastics into valuable products. The acidity and diffusion of zeolites play a critical role in determining the efficiency of this process. However, conventional aluminum-containing zeolites exhibit excessive acidity, which results in increased gas formation and a diminished yield of liquid products. Additionally, microporous zeolites with limited diffusion of large molecules significantly impair their activity and overall utilization efficiency. In this study, we developed gallium-modified MFI zeolite catalysts (Ga-MFI) that possess a well-balanced micro- and mesoporosity along with controlled acidity. These Ga-MFI catalysts exhibited enhanced diffusion properties and moderate acidity, which contributed to an improved gasoline yield (64.84–77.69%), alongside a significant reduction in liquefied gas yield (from 23.21% to 13.07%) during the catalytic cracking of low-density polyethylene (LDPE) when compared to the ZSM-5 catalyst. Furthermore, the Ga-MFI catalysts demonstrated a significant enhancement in the selectivity for cycloalkenes within the liquid products, increasing from 35.62% to 51.53%. This improvement can be attributed to the promotion of bimolecular cracking reactions occurring on moderate acidic sites, which facilitate olefin formation, as well as the high concentration of Lewis acid sites that aid in the dehydrogenation of cycloalkanes to cyclo-olefins. These findings underscore the potential of Ga-MFI zeolite as a promising catalyst for the sustainable conversion of plastic wastes.
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Nano Research
·
2021
·Vol. 14
·期 11
·4304-4313
·
IF 8.897
Zhai Yi,Wang Fumin,Zhang Xubin,Lv Guojun,Wu Yuzhou,Jiang Tao,Zhang Qing,Li Mengyue,Li Mengyao,Liu Yongkui
How to directionally design the hollow zeolite via a green route is of great significance. Here, we successfully synthesized the hollow Fe-silicate-1 encapsulated ultra-small Fe 2 O 3 nanoparticles (2.5 nm) with higher yield (85.2%) by mother liquid than traditional dissolution-recrystallization for the first time, which was achieved by precisely regulating the number and distribution of defects in zeolite and cleverly utilizing the TPAOH and nuclei in mother liquor. The effects of synthetic temperature, synthetic period and addition amount of parent zeolite on the formation of hollow zeolite have been investigated and the effect of synthetic conditions on the defects in parent zeolite has been also firstly quantified. The corresponding formation mechanism has been proposed. The abundant inner defects provided by the zeolite synthesized at 130 °C for 1 day and large amount of TPAOH remaining in mother liquid are conducive to the formation of hollow zeolite. Meanwhile, both parent zeolite and nuclei (4-, 5-member rings and structure units) in mother liquid obtained at 130 °C play the crucial roles in enhancing the zeolite yield. Notably, Fe 2 O 3 nanoparticles could decompose into small fragments by the interaction with nuclei in mother liquid. Partial ultra-small Fe 2 O 3 nanoparticles would be encapsulated in cavity and the rest could be inserted in the zeolite framework, which is significantly different from the conventional dissolution-recrystallization mechanism. The obtained encapsulated catalyst shows the superior catalytic performance and stability in phenol and tetracycline degradation reactions.
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