New Strategy to Synthesis of Hierarchical Mesoporous Zeolites

Gu, Fangna; Feng, Wei; Yang, Jincai; Lin, Na; Wei, Lin; Wang, Ying; Zhu, Jian Hua

doi:10.1021/cm903785r

Cited by 132 publications

(88 citation statements)

References 52 publications

(89 reference statements)

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“…[10][11][12][13][14] The synthetic elegance of bottom-up methods is counteracted by a low chance for industrialization, since they commonly necessitate the use of costly and commercially unavailable reactants as mesopore-inducing agents, [15][16][17][18][19] and/ or lead to products not easily separated from the mother liquor, e.g., nano-crystals or nano-sheets. [19,20] On the other hand, top-down approaches such as demetallation are highly effective and scalable at a reasonable cost.…”

Section: Introductionmentioning

confidence: 99%

Hierarchical Y and USY Zeolites Designed by Post‐Synthetic Strategies

Verboekend

Vilé

Pérez‐Ramírez

2011

Adv Funct Materials

302

218

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Strategic combinations of affordable and scalable post‐synthetic modifications enabled to design a broad family of hierarchical Y and USY zeolites (FAU topology) independent on the Si/Al ratio. Pristine (Y, Si/Al = 2.4), steamed (USY, Si/Al = 2.6), and steamed and dealuminated (USY, Si/Al = 15 and 30) zeolites were exposed to a variety of acid (H4EDTA and Na2H2EDTA) and base (NaOH) treatments, which led to the introduction of mesopore surfaces up to 500 m2 g−1, while preserving the intrinsic zeolite properties. Pristine Y and USY zeolites (Si/Al ∼ 2.5) required mild dealumination (to Si/Al > 4 in the case of Y) to facilitate subsequent efficient desilication. Alkaline treatment of Y and USY zeolites with low Si/Al ratios (∼4–6) led to an abundance of Al‐rich debris, which could be removed by a subsequent mild acid wash. On the other hand, severely steamed and dealuminated, hence Si‐rich, USY zeolites (Si/Al = 15 and 30) proved extremely sensitive to the alkaline solution, displaying facile dissolution and substantial amorphization. For the latter group of ultra‐stable Y zeolites, the presence of TPA+ in the alkaline solution enables to protect the zeolite structures upon the introduction of mesoporosity by desilication, preserving crystallinity and micropore volume. The sorption and catalytic properties of the hierarchical Y and USY zeolites were superior compared to the conventional counterparts.

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Section: Introductionmentioning

confidence: 99%

Hierarchical Y and USY Zeolites Designed by Post‐Synthetic Strategies

Verboekend

Vilé

Pérez‐Ramírez

2011

Adv Funct Materials

302

218

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“…Among which, introducing mesopores into the original structure of microporous zeolites is one of the most efficient methods [5][6][7]. Such mesostructured zeolite materials have not only the advantages of micropores, which ensure acidity and shape selectivity, but also the advantages of mesopores, which promote the adsorption of molecules [8][9][10] and diffusion rate for mass transfer within zeolites [8,[11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Adsorption and Diffusion of Xylene Isomers on Mesoporous Beta Zeolite

Song

et al. 2015

Catalysts

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Abstract:A systematic and detailed analysis of adsorption and diffusion properties of xylene isomers over Beta zeolites with different mesoporosity was conducted. Adsorption isotherms of xylene isomers over microporous and mesoporous Beta zeolites through gravimetric methods were applied to investigate the impact of mesopores inside Beta zeolites on the adsorption properties of xylene isomers in the pressure range of lower 20 mbar. It is seen that the adsorption isotherms of three xylene isomers over microporous and mesoporous Beta zeolites could be successfully described by the single-site Toth model and the dual-site Toth model, respectively. The enhanced adsorption capacities and decreased Henry's constants (KH) and the initial heats of adsorption (Qst) for the all xylene isomers are observed after the introduction of mesopores in the zeolites. For three xylene isomers, the order of Henry's constant is o-xylene > m-xylene > p-xylene, whereas the adsorption capacities of Beta zeolite samples for xylene isomers execute the following order of o-xylene > p-xylene > m-xylene, due to the comprehensive effects from the molecular configuration and electrostatic interaction. At the same time, the diffusion properties of xylene isomers in the mesoporous Beta zeolites were also studied through the desorption curves measured by the zero length column (ZLC) method at 333-373 K. It turned out that the effective diffusion time constant (Deff/R 2 ) is a growing trend with the increasing mesoporosity, whereas the tendency of the activation energy is just the reverse, indicating the contribution of mesopores to facilitate molecule diffusion by shortening diffusion paths and reducing diffusion resistances. Moreover, the diffusivities of three xylene isomers in all Beta zeolites follow an order of p-xylene > m-xylene > o-xylene OPEN ACCESSCatalysts 2015, 5 2099 as opposed to KH, conforming the significant effects of adsorbate-adsorbent interaction on the diffusion.

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“…Mesoporous Y zeolite can also be obtained using surfactant templates [33][34][35][36][37][38][39][40]. Garcia-Martinez et al reported about the scale-up of a surfactant-templated process to prepare mesoporous Y zeolite; composite catalysts based on such hierarchical zeolite Y showed improved yield of valuable gasoline and light cycle oil (LCO) products over bottoms and coke in FCC catalyst evaluation [41].…”

Section: Introductionmentioning

confidence: 99%