Mesoporous Zeolitic Materials (MZMs) Derived From Zeolite Y Using a Microwave Method for Catalysis

Abstract

Mesostructured zeolitic materials (MZMs) with relatively high acidity in comparison with the mesoporous siliceous MCM-41 were prepared via an efficient, mild, and simple post-synthetic treatment of Y zeolite facilitated by microwave irradiation, i.e., microwave-assisted chelation (MWAC). The disordered mesoporous aluminosilicates materials (DMASs) of MZM were created from Y zeolite in the absence of using mesoscale templates. The prepared DMASs showed the good mesoporous features with the mesopore area and volume of ∼260 m 2 g −1 and ∼0.37 cm 3 g −1 , respectively, and with the mesopore sizes distributed in a range of 2-10 nm. MZMs possess a total acidity of about 0.6 mmol g −1 and exhibited comparatively superior catalytic activity to the parent Y zeolite and MCM-41 in the vapor phase catalytic dealkylation of 1,3,5-triisopropylbenzene (TiPBz) and liquid phase catalytic aldol condensation of benzaldehyde with 1-heptanal. Although the yield loss was inevitable for preparing MZMs using the MWAC method, the preliminary economic analysis of the preparation cost of MZMs showed the promise. Additionally, a comprehensive comparison of the state-of-the-art mesoporous materials concerning their sustainable aspects was made, showing that MZMs are promising mesoporous materials for further development and functionalization for catalysis.

An efficient microwave-assisted chelation (MWAC) post-synthetic modification method to produce hierarchical Y zeolites

“…Additionally, MW-assisted post-synthetic modification of zeolites and zeotypes (in the liquid-phase) regarding the acidity [21][22][23][24] and porosity [25][26][27][28] was also attempted using the mineral acids and bases. Especially, our recent work has shown that the combination of chelation dealumination with the microwave irradiation was highly efficient to prepare mesoporous zeolitic materials [29,30].…”

“…Here we report the extended investigation of the post-synthetic treatment protocol involving chelation dealumination under MW irradiation (i.e., MW-Assisted Chelation, MWAC [29,30]) for producing the modified synthetic zeolites with hierarchical pore structures. Specifically, and significantly, the MWAC method has enabled the preparation of hierarchical FAU zeolite Y on the minute timescale, and the obtained Y zeolites show exceptional hierarchical mesoporous features with the specific external surface area (Sext.)…”

State of the Art and Perspectives of Hierarchical Zeolites: Practical Overview of Synthesis Methods and Use in Catalysis

“…This proves that the MWAC method is a time-(and cost-) effective method, which may be classified as environmentally friendly and sustainable. [297] Top-Down Methods-Desilication: Like previously mentioned, a dealumination step may be required previous to desilication to remove protective Al species. Starting with a publication from Li et al, this group performed such an alkaline treatment that was preceded by two dealumination steps: I) a steam treatment and II) an acid treatment (e.g., fluorosilicic acid, HCl).…”

“…This proves that the MWAC method is a time‐ (and cost‐) effective method, which may be classified as environmentally friendly and sustainable. [ 297 ]…”

Palladium-doped hierarchical ZSM-5 for catalytic selective oxidation of allylic and benzylic alcohols

“…One major drawback of zeolites is their microporous nature, which can hinder mass diffusion leading to coking and reduced in-pore diffusion of substrates. Incorporating complementary secondary porosity, either mesopores or macropores, has been demonstrated to help alleviate coking during gas-phase reactions [18][19][20]. It also can impart beneficial attributes to liquid-phase reactions through increased accessibility of active sites [21].…”