Facile Preparation of a Binderless Hierarchical Beta Zeolite in Shaped Form and with Improved Acidity for Catalysis

Author(s):  
Jiaxu Liu ◽  
Zhenmei Zhang ◽  
Chunyan Liu ◽  
Gianvito Vilé ◽  
Guang Xiong ◽  
...  

<div> <div> <div> <div> <p>The synthesis of a technical hierarchical nanosized zeolite catalysts without growth modifiers and binders remains a major challenge in catalysis. Herein, we report a new synthetic approach to directly produce hierarchical nanosized Beta zeolites in technical form, without any binders in the final material. The synthesis consists of two steps, where a Beta zeolite powder is first shaped using tetraethyl orthosilicate; the extrude is then recrystallized at high temperature in the presence of tetraethylammonium hydroxide solution. This transforms the SiO2 binders into zeolite framework. A variety of characterization methods were applied to unlock structure-properties relationships of the materials and demostrate their catalytic functionality. We believe that this work opens avenues for the advanced manufacturing of hierarchical zeolite materials in shaped form, and will find useful applications in catalysis and materials science. </p> </div> </div> </div> </div>

2020 ◽  
Author(s):  
Jiaxu Liu ◽  
Zhenmei Zhang ◽  
Chunyan Liu ◽  
Gianvito Vilé ◽  
Guang Xiong ◽  
...  

<div> <div> <div> <div> <p>The synthesis of a technical hierarchical nanosized zeolite catalysts without growth modifiers and binders remains a major challenge in catalysis. Herein, we report a new synthetic approach to directly produce hierarchical nanosized Beta zeolites in technical form, without any binders in the final material. The synthesis consists of two steps, where a Beta zeolite powder is first shaped using tetraethyl orthosilicate; the extrude is then recrystallized at high temperature in the presence of tetraethylammonium hydroxide solution. This transforms the SiO2 binders into zeolite framework. A variety of characterization methods were applied to unlock structure-properties relationships of the materials and demostrate their catalytic functionality. We believe that this work opens avenues for the advanced manufacturing of hierarchical zeolite materials in shaped form, and will find useful applications in catalysis and materials science. </p> </div> </div> </div> </div>


Author(s):  
Chuanyu Yang ◽  
Zhongwen Dong ◽  
Weifeng Chu ◽  
Yanan Wang ◽  
Dongpu Zhao ◽  
...  

A series of Beta zeolite catalysts with controllable particle sizes and similar Si/Al ratios were prepared by introducing imidazole (IMD) into the synthesis system and used for a liquid-phase transalkylation...


Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 504 ◽  
Author(s):  
Wenming Hao ◽  
Weimin Zhang ◽  
Zaibin Guo ◽  
Jinghong Ma ◽  
Ruifeng Li

To improve the catalytic performance of zeolite catalysts in reactions involving bulky molecules, a series of mesoporous Beta zeolite were prepared using organic functionalized fumed silica as the silicon source, which were thoroughly characterized in terms of porosity and acidity. The peaks in X-ray diffraction (XRD) patterns showed broadening, and the external surface area and mesoporosity increased progressively when the content of organic functionalization increased. An infrared (IR) spectroscopy study of adsorbed probe molecules, including pyridine (Py-IR), 2,6-ditertbutylpyridine (DTBPy-IR) and pivalonitrile (Pn-IR), showed that the improvement of mesoporosity increased the accessibility of acidic sites. In the catalytic benzylation of naphthalene with benzyl chloride (BC) over the mesoporous Beta zeolite catalysts, the conversion of BC was significantly increased when the accessibility of Brönsted acid sites improved. The increase of mesoporosity not only improved the diffusion ability of the reactants and products, but also increased the accessibility of acid sites, which greatly enhanced the activity of the mesoporous Beta zeolite catalysts. It is highlighted that the interdependence of mesoporosity, acid type, acid concentration, and strength of the mesoporous Beta zeolites on the catalytic performance in the benzylation of naphthalene with BC was comprehensively studied.


2020 ◽  
Vol 849 ◽  
pp. 34-39
Author(s):  
Dijan Supramono ◽  
Syafira Tiaradiba

The non-oxygenated fraction of bio-oil is precursor of the formation of biofuel because it contains hydrocarbon only. Zeolite catalysts have been proved to improve the yields of non-polar fraction of bio-oil in case of fast co-pyrolysis. In the present work, the catalysts were applied to slow co-pyrolysis to investigate their effect on the yields and compositions of non-oxygenated fractions of bio-oil. The co-pyrolysis was conducted in a stirred tank reactor using non catalyst (thermal co-pyrolysis), natural zeolite and H-beta zeolite catalysts with heating rate of 5°C/minute from ambient temperature to 500°C and PP composition in combined feed varied 0, 50, and 100% weight of PP. As biomass, the present study used corn cobs. The results show that synergistic effect on the yield of non-oxygenated fraction in co-pyrolysis involving natural zeolite was lower than that in thermal co-pyrolysis and co-pyrolysis involving H-beta-zeolite exhibited negative synergistic effect. H-NMR analysis of the fraction from co-pyrolysis involving 50% weight of PP shows that the bio-oil contained approximately methyl H of about 55% by mol, methine H of 20% and methylene H of about 15% irrespective of catalysts used. This composition was closer to that of commercial gasoline rather than commercial diesel compositions.


2018 ◽  
Author(s):  
Felix Hemmann ◽  
Jonathan Hackebeil ◽  
Andreas Lißner ◽  
Florian Mertens

Molecular sieves with beta zeolite topology are promising catalysts for various reactions as they exhibits extraordinary Lewis acidity. However, their industrial application and related research in academica is hindered because their synthesis is time consuming and typically involves toxic chemicals as hydrofluoric acid. Therefore, tetraethylammonium fluorid was tested as a non-toxic fluotide source for the synthesis of beta zeolites. In combination with the previously reported nano-seeded growth method, a fast synthesis of beta zeolites only involving non-toxic chemicals was possible. Synthesized zeolites show comparable selectivity in the Bayer-Villinger oxidation as conventional zeolites synthesized with hydrofluoric acid.<br>


2005 ◽  
Vol 23 (3) ◽  
pp. 255-266 ◽  
Author(s):  
J. O'Brien ◽  
T. Curtin ◽  
T.F. O'Dwyer

Zeolite beta, a large-pore zeolite, was investigated in this study with a view to examining it as a potential adsorbent for the removal of aniline from aqueous solutions. Two different metal-loaded zeolites were prepared by exchanging H-beta zeolite (SiO2/Al2O3 = 75:1) with copper. The influence of exchanged copper on the uptake level was assessed. The effect of varying the silica-to-alumina ratio of the H-beta zeolite on the aniline uptake level was also examined, using three different H-beta zeolites with ratios of 25:1, 75:1 and 150:1 as adsorbents. The sorption experiments indicated an uptake level of ca. 110–120 mg/g for each zeolite and this level was also adsorbed by the copper-modified H-beta zeolites (SiO2/Al2O3 = 75:1). In all cases, the adsorption process followed the Langmuir model for adsorption and the level of aniline adsorbed was largely unaffected by a change in temperature or the presence of extra framework copper. The stability of the exchanged copper on these zeolites was then examined by measuring the quantity of copper leached from each zeolite into solution as a function of pH. Minimum copper leaching was observed in the pH range 5–11. This provided a stable pH working range for the adsorbent materials.


Author(s):  
Yunlong Xu ◽  
Yuanyuan Fang ◽  
Jingjing Cao ◽  
Ping Sun ◽  
Cheng Min ◽  
...  

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