Enhanced thermal stability of hierarchical Y zeolites obtained by acid and subsequent base treatments

Vu, Xuan Hoan; Marschall, Mathias S.; Tran, Van Tri; Ngo, Thuy Phuong; Dang, Tuan Thanh; Dinh, Duc Manh; Dao, Thi Kim Thoa; Busse, Oliver; Weigand, Jan J.

doi:10.1016/j.jpcs.2021.109962

Cited by 5 publications

(2 citation statements)

References 24 publications

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“…Acidic EDTA solution can also serve as an etchant for combined acid-base etching. For instance, Vu et al [33] described a process for preparing hierarchical Y zeolites utilizing the acidalkali combined treatment. The parent material NaY was treated initially with an aqueous EDTA solution to extract Al from the framework, and then a NaOH aqueous solution was used to extract Si and modify it with lanthanide ions.…”

Section: Composite Etching By Acid-alkalimentioning

confidence: 99%

Methods for Preparing Hierarchical Zeolites by Chemical Etching and Their Catalytic Applications: A Review

et al. 2023

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Zeolites are widely used in petrochemical processes and refineries due to their well‐ordered microporous network and large surface area. However, the diffusion of reactants and products is hampered by the narrow microporous channels, causing limitations. To overcome this challenge, modifying the pore structure is crucial, and the chemical etching technique is a powerful tool that introduces mesopores and macropores, consequently enhancing mass transfer and accessibility. Diverse chemical etching methods have been invented, including exposure to both acids (organic/inorganic acids), alkali (organic/inorganic alkali), and neutral etchants (e. g., ammonium fluoride). This review summarizes and assesses the chemical etching methods and their relevance to catalytic cracking reactions, methanol to hydrocarbons (MTH), and biomass conversion. The potential of zeolites with modified pore structures has motivated researchers to develop novel methods to tackle the practical challenges associated with their applications.

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Section: Composite Etching By Acid-alkalimentioning

confidence: 99%

Methods for Preparing Hierarchical Zeolites by Chemical Etching and Their Catalytic Applications: A Review

et al. 2023

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“…Brønsted acid sites in zeolites reduce their hydrothermal stability because they attract water molecules to Al tetrahedra, − which can start dealumination reactions. Despite affecting zeolite hydrothermal stability, Brønsted acid sites on zeolites are of great interest due to their catalytic activity in various reactions, not only for petroleum cracking. ,− Upon binding lanthanum, changes in the acid strength of the remaining zeolite Brønsted acid sites have been observed, increasing zeolite stability as well. ,, …”

Section: Introductionmentioning

confidence: 99%

Effect of Lanthanum Ions on the Brønsted Acidity of Faujasite and Implications for Hydrothermal Stability

2021

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Lanthanum stabilizes faujasite in fluid catalytic cracking and allows for longer catalyst material lifetimes in petroleum refining. Despite its extensive use for decades, a thorough, mechanistic understanding of how lanthanum increases the hydrothermal stability of faujasite remains out of reach. Dealumination, the main contributor to loss of zeolitic hydrothermal stability, occurs by reactions that involve water molecules. Brønsted acid sites give desired catalytic properties to zeolites; however, they reduce hydrothermal stability because they attract water molecules to aluminum tetrahedra, promoting dealumination. In this work, the energetically favored binding sites of water molecules and lanthanum ions in hydrogen-exchanged faujasite with a Si/Al ratio of five were determined with density functional theory calculations and ab initio molecular dynamics simulations. Also, the Brønsted acid strength of faujasite was quantified, using constrained ab initio molecular dynamics simulations, with and without lanthanum ions bound to faujasite. Results indicate that water and lanthanum ions are energetically favored to bind in the same sites in faujasite, and that lanthanum ions increase the acidity of Brønsted acid sites adjacent to, and not adjacent to, bound lanthanum ions in faujasite. Implications toward hydrothermal stability are discussed, because lanthanum ions will compete with water molecules for binding sites, as well as change the protonation state, and therefore hydrophilicity, of aluminum tetrahedra in faujasite.

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Synthesis and catalytic performance of hierarchically porous catalysts during pyrolysis of lipids to produce liquid hydrocarbons: A review

Wang,

Guo,

Song

et al. 2024

Applied Catalysis A: General

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Enhanced thermal stability of hierarchical Y zeolites obtained by acid and subsequent base treatments

Cited by 5 publications

References 24 publications

Methods for Preparing Hierarchical Zeolites by Chemical Etching and Their Catalytic Applications: A Review

Methods for Preparing Hierarchical Zeolites by Chemical Etching and Their Catalytic Applications: A Review

Effect of Lanthanum Ions on the Brønsted Acidity of Faujasite and Implications for Hydrothermal Stability

Synthesis and catalytic performance of hierarchically porous catalysts during pyrolysis of lipids to produce liquid hydrocarbons: A review

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