Dual Template Preparation of MFI Zeolites with Tuning Catalytic Properties in Alkylation of Mesitylene with Benzyl Alcohol

Synthesis of Two-Dimensional Zeolite Nanosheets Applied to the Catalytic Cracking of a Waste Cooking Oil Model Compound to Produce Light Olefins

Hierarchical zeolites can provide multidimensional spatial networks and, therefore, have significant potential as catalysts for the cracking of biomass to generate light olefins. The present work synthesized the diquaternary ammonium-type surfactant [C18H37-N+(CH3)2-(CH2)6-N+(CH3)2-C6H13]Br2, incorporating hydrophobic 18-carbon alkyl groups for usage as a structure-directing agent. This compound was subsequently used to prepare nanosheets of a hierarchical ZSM-5 two-dimensional zeolite (HNZSM-5) through a one-pot hydrothermal method. The crystal phase, morphology, and hierarchical structure of the HNZSM-5 were analyzed using various techniques, including X-ray diffraction, electron microscopy, and N2 adsorption/desorption. When applied to the catalytic cracking of a waste cooking oil model compound, the HNZSM-5 exhibited superior activity and stability compared with a conventional ZSM-5. This performance was attributed to the more accessible acid sites and unique lamellar structure of the former material. The HNZSM-5 also outlasted the conventional zeolite, showing deactivation after 45 h of reaction compared with 20 h, indicating exceptional stability and excellent resistance to coking.

Facile Synthesis of Nanosheet-Stacked Hierarchical ZSM-5 Zeolite for Efficient Catalytic Cracking of n-Octane to Produce Light Olefins

The development of an effective strategy for synthesizing two-dimensional MFI zeolites has attracted more and more attention. Herein, nanosheet-stacked hierarchical ZSM-5 zeolite was obtained by a seed-assisted hydrothermal synthesis route using a small amount of [C18H37-N+(CH3)2-C6H12-N+(CH3)2-C6H12]Br2 (C18-6-6Br2) as a zeolite structure-directing agent and triethylamine (TEA) as a zeolite growth modifier. By varying the molar ratio of C18-6-6Br2/TEA from 2.5/0 to 2.5/40, the morphologies and textural properties of the resultant HZ5-2.5/x catalysts were finely modulated. By increasing x from 5 to 40, the morphology of the HZ5-2.5/x changed from unilamellar assembly with narrow a–c plane to intertwined nanosheets with wide a–c plane and multilamellar nanosheets with house-of-cards morphology. The thickness of these nanosheets was almost 8–10 nm. In addition, selectivity to light olefins reached 70.7% for the HZ5-2.5/10 catalyst, which was 6.6% higher than that for CZSM-5 (64.1%). Furthermore, the MFI zeolite nanosheets exhibited better anticoking stability within the 60 h reaction time compared to conventional ZSM-5 zeolite, which could be attributed to the short diffusion path and hierarchical porosity. This work will provide valuable insights into the rational design of novel zeolite catalysts for the efficient cracking of hydrocarbons.

Development of highly efficient Friedel-Crafts alkylations with alcohols using heterogeneous catalysts under continuous-flow conditions

The development of Friedel–Crafts alkylations with alcohols under continuous-flow conditions using heterogeneous catalysts is reported. The reactivities and durabilities of the examined catalysts were systematically investigated, which showed that montmorillonite clay is the best catalyst for these reactions. A high turnover frequency of 9.0 × 10² h⁻¹ was recorded under continuous-flow conditions, and the continuous operation was successfully maintained over one week.

Efficient and highly durable catalysts were developed for Friedel–Crafts alkylation using alcohols under continuous flow conditions.

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

Microporous zeolites have proven to be of great importance in many chemical processes. Yet, they often suffer from diffusion limitations causing inefficient use of the available catalytically active sites. To address this problem, hierarchical zeolites have been developed, which extensively improve the catalytic performance. There is a multitude of recent literature describing synthesis of and catalysis with these hierarchical zeolites. This review attempts to organize and overview this literature (of the last 5 years), with emphasis on the most important advances with regard to synthesis and application of such zeolites. Special attention is paid to the most common and important 10- and 12-membered ring zeolites (MTT, TON, FER, MFI, MOR, FAU, and *BEA). In contrast to previous reviews, the research per zeolite topology is brought together and discussed here. This allows the reader to instantly find the best synthesis method in accordance to the desired zeolite properties. A summarizing graph is made available to enable the reader to select suitable synthesis procedures based on zeolite acidity and mesoporosity, the two most important tunable properties.

In Situ Recrystallization of Mesoporous Carbon-Silica Composite for the Synthesis of Hierarchically Porous Zeolites

Hierarchically porous ZSM-5 was prepared by utilizing a two-step crystallization procedure with carbon–silica composites as precursors. The hierarchically porous zeolites obtained a regular mesoporous structure with aluminum incorporated into the carbon–silica composite frameworks. The carbon–silica composite zeolites were characterized by XRD, TEM, SEM, and nitrogen adsorption/desorption. As-prepared hierarchical zeolites were used in the 1,3,5-triisopropylbenzene (TIPB) cracking reaction and exhibited significantly high TIPB conversion, while the accessibility factors were also determined.