Improved glycerol dehydration through hierarchical beta zeolite

Template free synthesis of hierarchical porous zeolite Beta with natural kaolin clay as alumina source

Synthesis of hierarchical zeolite Beta with low organic template content via the steam-assisted conversion method

Transalkylation of Multi-secbutylbenzenes with Benzene over Hierarchical Beta Zeolite

Beta zeolite, a crystal material with a three-dimensional twelve-ring cross-channel structure, has many advantages, such as high Brønsted acid concentration, high Si/Al ratio, thermal/hydrothermal stability, and large surface area. Due to these advantages, beta zeolite shows excellent catalytic performance in petroleum refining and petrochemical processes. However, traditionally microporous beta zeolite has strong steric hindrance and diffusion restrictions, which hinder large molecules from passing through its internal channels. In addition, carbon deposition occurs, resulting in catalyst deactivation. The main strategy to solve this problem is to prepare nanosized or hierarchical beta zeolites, which allow for large molecule conversion and shortening diffusion pathways. Therefore, researchers have explored different synthesis strategies to prepare beta zeolite with different particle sizes and porosities to obtain better zeolite catalysts. This paper briefly describes the recent research progress in the preparation of nanosized and hierarchical beta zeolite. Additionally, the mechanisms of various preparation methods, structural characteristics, and applications of the materials are introduced in detail. Furthermore, the main problems existing in its industrial application are describing by comparing the advantages and disadvantages of the different methods to prepare optimally nanosized and hierarchical zeolite to meet the requirements of industrial development.

“Burr Puzzle”-Like Hierarchical Beta zeolite composed of crisscrossed nanorods

The combined influence of the catalyst acidity and porosity features on the transesterification of soybean oil with methanol was investigated over micro/mesoporous hierarchical Beta (Si/Al = 18 and 30), conventional microporous Beta (Si/Al = 23 and 43) and MCM-22 (Si/Al = 40) zeolites. All the catalysts were characterized as to their structure and texture by X-ray diffraction and N2 physisorption, respectively. Their acid features were assessed by adsorption microcalorimetry, using NH3 as probe molecule. Catalytic testing was carried out in batch at 453 K and 4 MPa. The nature of the organic material adsorbed/trapped in the catalyst during reaction (“coke”) was determined by GC/MS after solvent extraction. Fatty acid methyl esters (FAMEs) yields of 22–40 mol% were attained with a reaction time of 24 h over the conventional Beta and MCM-22 samples, whereas remarkably higher values (50–70 mol%) were observed over the hierarchical Beta zeolites. For both the hierarchical and conventional zeolites, the initial FAMEs yield was found to increase with the concentration of the acid sites able to adsorb ammonia with strength higher than ca. 100 kJ mol−1. In comparison with the conventional zeolites of similar acidity, the methyl esters yield over the hierarchical zeolites was twice to three times higher, as a consequence of the enhanced reactants diffusion in their secondary mesoporous system. The presence of free fatty acids in the reaction mixture and the nature of the coke revealed that several acid-catalyzed reactions and thermal degradation processes can occur simultaneously with transesterification. A general scheme for the different reaction pathways for the oil transformation was outlined.

The ever‐growing need to increase the efficiency of crude oil refining raises the prospects for utilizing advanced catalytic materials to supply increasing global demands for fine chemicals and petrochemicals. Zeolites have been used as indispensable catalysts in many commercial refining processes. Among them, zeolite beta is one of the most widely produced zeolite materials with industrial significance due to its large micropores and three‐dimensional pore structures. This article discusses recent progress on hierarchical beta zeolites from various synthetic strategies. Using zeolite beta as a representative case, we provide an overview on key aspects that are applicable to different zeolites via a variety of topics, such as selection of different template materials, tailoring of mesopore sizes by base leaching, organotemplate‐free synthesis of hierarchical zeolites, and selective desilication. This article concludes with a perspective on the design of scalable hierarchical zeolites that are more relevant as industrial catalysts in commercial processes.

A hierarchical Beta zeolite has been successfully mass‐prepared hydrothermally and dynamically in a pilot‐scale autoclave by an economical and simple process with low‐cost raw materials. The characterization results indicated that the pilot‐scale hierarchical Beta zeolite has the same textural, structural, and acidic properties like the bench‐scale sample. Moreover, the catalyst composed of the pilot‐scale hierarchical H‐Beta zeolite showed higher activity and selectivity to the middle distillate than that containing microporous Beta zeolite in catalytic hydrocracking of vacuum gas oil (VGO) evaluated by an industrial pilot installation in running of 3000 h, due to the increased accessibility and the reduction of diffusion constraint of large molecules to acid sites in the Beta zeolite framework.

Novel hierarchical Beta zeolites have been successfully synthesized via a one‐pot dual‐templates strategy utilizing gemini organic surfactant and tetraethylammonium hydroxide (TEAOH)through hydrothermal process. The influence of several parameters on the formation of hierarchical Beta zeolite, the change in acidity and a possible growth scheme were systematically investigated. The physicochemical properties of these catalysts were characterized by PXRD, BET, SEM, HRTEM SAED, TG and NH3‐TPD techniques, and the performance as acid catalysts was verified using the transformation of EtOH as a model reaction. On one hand, WAXRD data indicated that decreasing the temperature of synthesis and increasing amounts of C12‐6‐12 in the process of synthesis resulted in lower crystallinity of Beta zeolites due to the BEA nuclei formation and crystal growth constrained by C12‐6‐12. On the other hand, SAXRD and HRTEM data evidenced that C12‐6‐12 initially generated a pseudo‐ordered mesoporous phase which was then partially occupied by the zeolite. After a period of ~96 h for crystallization, the hierarchy zeolite possessing 765.7 m2·g‐1 of Brunauer‐Emmett‐Tellerarea, and average mesopore size distribution of 3.51 nm can be synthesized, and its microporous structure has a good crystallinity and lower amounts of acid sites than that of the microporous Beta one. Furthermore, the as‐obtained hierarchical zeolite displayed lower deactivation rate mainly due to the less coke formation on the surface of catalyst. It is expected to develop more considerable potential application value for the hierarchical Beta zeolite structure in the near future.

Remarkable catalytic properties of hierarchical zeolite-Beta in epoxide rearrangement reactions

Synthesis of hierarchical Beta zeolite with uniform mesopores: Effect on its catalytic activity for veratrole acylation

Hierarchical beta zeolites obtained in the concentrated reaction mixtures (H2O/Si = 2.5) and micromesoporous materials synthesized using a dual-template approach from a zeolite beta precursor were rigorously characterized and tested in a sustainable and environmentally friendly process of α-pinene oxide isomerization. The highest yield of trans-carveol (42%) with chemopreventive activity of mammary carcinogenesis was achieved over low crystalline micromesoporous materials characterized by well-developed mesoporosity, an increased fraction of weak-to-medium Brønsted acid sites and low Brønsted and Lewis acid sites (BAS/LAS) ratio. In turn, highly crystalline hierarchical beta zeolites with a lower mesopore volume and the mesopore surface area, stronger Brønsted acidity, and a higher BAS/LAS ratio favored the formation of campholenic aldehyde (31% yield). The mechanism of the desired product and byproducts formation was discussed and its feasibility was confirmed by kinetic modeling.

Adsorptive desulfurization over hierarchical beta zeolite by alkaline treatment

Transalkylation of diisopropylbenzenes with benzene over hierarchical beta zeolite

P-Methyacetophenone, the acylated product of toluene finds a wide range of applications in the flavors and fragrance industry. It is typically produced on an industrial scale by Friedel-Crafts acylation of toluene with acetic anhydride using homogeneous, corrosive and polluting acid catalysts such as aluminium chloride. The pollution problems related to this process such as the disposal of catalyst and treatment of acidic effluent needs to be replaced by a green process. The current work reports on the activity of hierarchical zeolite Beta in the liquid phase acylation of toluene with acetic anhydride. The liquid phase reactions were carried out in the temperature range of 60-140 degrees C in an autoclave. The effect of various reaction parameters such as time-on-stream (TOS), mole ratio of reactants, catalyst loading, and reaction temperature on the rates of reaction has been investigated. Under the optimum reaction conditions the performance of hierarchical zeolite Beta was compared with nanocrystalline zeolite Beta. It was found that hierarchical zeolite Beta catalyst exhibit higher activity, which is due to the hierarchical porosity and to the nano size of the Beta zeolite catalyst particles allows faster diffusion of the products out of the catalyst.