De novo assembly of a mesoporous beta zeolite with intracrystalline channels and its catalytic performance for biodiesel production

Zhang, Qiangqiang; Ming, Weixing; Ma, Jinghong; Zhang, Jilong; Wang, Qianqian; Li, Ruifeng

doi:10.1039/c4ta00030g

Cited by 45 publications

(23 citation statements)

References 21 publications

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“…The mesoporous Beta zeolite samples used in this work were hydrothermally synthesized by employing organfunctioned nano-silica as silicon source, which was described in the previous paper [38]. Firstly, fumed silica (Aerosil 200, Degussa, Marl, NRW, Germany) was organic functioned with phenylaminopropyl-trimethoxysilane (PHAPTMS, Aldrich, Saint Louis, MO, USA), then obtained organo-silylated nano-SiO2 was used as silicon source, according to the molar composition of Al2O3: 38 org-SiO2: 1.5 Na2O: 10 TEAOH: 532 H2O, three mesoporous Beta zeolite samples with different mesoporosities were synthesized by adjusting silanization degree of nano-silica, and coded as Beta-n (n = 1, 2, 3).…”

Section: Materials and Characterizationmentioning

confidence: 99%

Adsorption and Diffusion of Xylene Isomers on Mesoporous Beta Zeolite

Song

et al. 2015

Catalysts

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Abstract:A systematic and detailed analysis of adsorption and diffusion properties of xylene isomers over Beta zeolites with different mesoporosity was conducted. Adsorption isotherms of xylene isomers over microporous and mesoporous Beta zeolites through gravimetric methods were applied to investigate the impact of mesopores inside Beta zeolites on the adsorption properties of xylene isomers in the pressure range of lower 20 mbar. It is seen that the adsorption isotherms of three xylene isomers over microporous and mesoporous Beta zeolites could be successfully described by the single-site Toth model and the dual-site Toth model, respectively. The enhanced adsorption capacities and decreased Henry's constants (KH) and the initial heats of adsorption (Qst) for the all xylene isomers are observed after the introduction of mesopores in the zeolites. For three xylene isomers, the order of Henry's constant is o-xylene > m-xylene > p-xylene, whereas the adsorption capacities of Beta zeolite samples for xylene isomers execute the following order of o-xylene > p-xylene > m-xylene, due to the comprehensive effects from the molecular configuration and electrostatic interaction. At the same time, the diffusion properties of xylene isomers in the mesoporous Beta zeolites were also studied through the desorption curves measured by the zero length column (ZLC) method at 333-373 K. It turned out that the effective diffusion time constant (Deff/R 2 ) is a growing trend with the increasing mesoporosity, whereas the tendency of the activation energy is just the reverse, indicating the contribution of mesopores to facilitate molecule diffusion by shortening diffusion paths and reducing diffusion resistances. Moreover, the diffusivities of three xylene isomers in all Beta zeolites follow an order of p-xylene > m-xylene > o-xylene OPEN ACCESSCatalysts 2015, 5 2099 as opposed to KH, conforming the significant effects of adsorbate-adsorbent interaction on the diffusion.

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Section: Materials and Characterizationmentioning

confidence: 99%

Adsorption and Diffusion of Xylene Isomers on Mesoporous Beta Zeolite

Song

et al. 2015

Catalysts

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“…deactivates rapidly and the methanol conversion reduces sharply to lower than 80%. Whereas HZSM-5(at) keeps high methanol conversion for more than 10 h, and decreases to less than 80% after 20 h. With the increase of surface area of catalyst by the introduction of mesopores into the microporous zeolite, more active sites are exposed to reactants and diffusion path length is decreased obviously, 51,54,65 resulting in the higher conversion rate and longer catalyst life in the catalyst HZSM-5(at). Therefore, the introduction of mesopore would be an important factor to obtain an active and stable catalyst.…”

Section: Resultsmentioning

confidence: 91%

“…catalyst is only 12% initially and then decreases to 5% after 12 h. Owing to the existence of intracrystalline mesopores, HZSM-5(at) offers a short diffusion path and a high diffusion rate. 51,54,65 The facts result in a high yield of fuel oil and lower cracking probability of long chain hydrocarbons to lighter paraffins, thus enhancing the resistance of the catalyst against deactivation.…”

Section: Resultsmentioning

confidence: 98%

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Structural features of core–shell zeolite–zeolite composite and its performance for methanol conversion into gasoline and diesel

Zheng

Sun

et al. 2016

J. Mater. Res.

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Zeolite-zeolite composite composed of alumina-rich hierarchically porous ZSM-5 cores and high-silicon MFI shells was prepared by a hydrothermal synthesis procedure, in which a commercial ZSM-5 zeolite with a SiO 2 /Al 2 O 3 of 36 was treated by an alkaline solution and then used as a supporter for epitaxial growth of a polycrystalline Silicalite-1 zeolite shell (denoted as MMZsa). Acid sites associated with framework Al on exterior surfaces of ZSM-5 zeolite cores are therefore passivated in different degrees by the epitaxial MFI zeolite shell. The structural, crystalline, and textural properties of the as-synthesized samples were characterized by x-ray powder diffraction (XRD), energy-dispersive x-ray spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), N 2 adsorption-desorption, in situ IR spectra of pyridine and NH 3 -TPD. Aluminum species were observed to transfer from the alumina-rich cores to the high-silica shells. The adjustable thickness and SiO 2 /Al 2 O 3 ratio of the shell offer the as-synthesized composite a potential and high-efficiency catalyst for methanol conversion into gasoline and diesel. As compared with the commercial ZSM-5 zeolite, the composite catalyst exhibits excellent catalytic performances with a longer catalytic life as well as a higher conversion and a slightly higher yield of diesel oil.

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“…In the present work, we report the preparation of hierarchical zeolite CaA single crystals with micro-, meso-and macroporous structure by using organo-functionalized mesoporous silica (MS) as silica sources in a one-pot hydrothermal system, which is based on bond-blocking principles of organic moiety linked on the surface of the silica through Si-C covalent bonds established by our research group [25,26]. The resultant CaA zeolites are characterized by XRD, SEM/TEM, N 2 adsorption/desorption and NH 3 -TPD techniques to investigate the influence of silanization degree over the MS surface on the crystalline and pore structure as well as acidity of synthesized samples.…”

Section: Introductionmentioning

confidence: 99%

A Hierarchically Micro-Meso-Macroporous Zeolite CaA for Methanol Conversion to Dimethyl Ether

et al. 2016

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Abstract:A hierarchical zeolite CaA with microporous, mesoporous and macroporous structure was hydrothermally synthesized by a "Bond-Blocking" method using organo-functionalized mesoporous silica (MS) as a silica source. The characterization by XRD, SEM/TEM and N 2 adsorption/desorption techniques showed that the prepared material had well-crystalline zeolite Linde Type A (LTA) topological structure, microspherical particle morphologies, and hierarchically intracrystalline micro-meso-macropores structure. With the Bond-Blocking principle, the external surface area and macro-mesoporosity of the hierarchical zeolite CaA can be adjusted by varying the organo-functionalized degree of the mesoporous silica surface. Similarly, the distribution of the micro-meso-macroporous structure in the zeolite CaA can be controlled purposely. Compared with the conventional microporous zeolite CaA, the hierarchical zeolite CaA as a catalyst in the conversion of methanol to dimethyl ether (DME), exhibited complete DME selectivity and stable catalytic activity with high methanol conversion. The catalytic performances of the hierarchical zeolite CaA results clearly from the micro-meso-macroporous structure, improving diffusion properties, favoring the access to the active surface and avoiding secondary reactions (no hydrocarbon products were detected after 3 h of reaction).

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De novo assembly of a mesoporous beta zeolite with intracrystalline channels and its catalytic performance for biodiesel production

Abstract: A mesoporous beta zeolite was hydrothermally prepared directly by silanizing silica without any mesoporous template via the bond-blocking principle.

Cited by 45 publications

References 21 publications

Adsorption and Diffusion of Xylene Isomers on Mesoporous Beta Zeolite

Adsorption and Diffusion of Xylene Isomers on Mesoporous Beta Zeolite

Structural features of core–shell zeolite–zeolite composite and its performance for methanol conversion into gasoline and diesel

A Hierarchically Micro-Meso-Macroporous Zeolite CaA for Methanol Conversion to Dimethyl Ether

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