Hierarchical porous nano-MFI zeolite-pillared montmorillonite clay synthesized by recrystallization for hydrocracking of residual oil

Ren, Zhiming; Li, Baoshan; Yue, Liwen; Wu, Naijin; Lv, Kaixuan; Han, Chunying; Li, Jianjun

doi:10.1039/c5ra07403g

Cited by 7 publications

(3 citation statements)

References 33 publications

(53 reference statements)

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“…Recently, considerable attention has been paid to layered zeolites with a thickness varying from one to several unit cells. − These systems possess short diffusion lengths, potentially overcoming diffusion and mass transfer limits. Various types of zeolites have been synthesized in the nanosheet form with different possible interlayer linkers ,− with an aim at targeting various catalytic systems such as isomerization and hydrocracking, − selective formation of molecules, ,− and epoxidation reactions. − Although zeolite nanosheets have been also considered for adsorption − and membrane separation systems, zeolite nanosheets specifically as RO membranes for water desalination have been greatly overlooked in the literature. The small thickness of layered zeolites (i.e., short diffusion distance) along with their excellent chemical and physical resistance make zeolite nanosheets a promising type of RO membrane materials in water desalination.…”

Section: Introductionmentioning

confidence: 99%

Atomistic Understanding of Zeolite Nanosheets for Water Desalination

2017

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Reverse osmosis constitutes a large portion of currently operating commercial water desalination systems. Employing membranes with large water fluxes while maintaining high salt rejection is of central importance in decreasing the associated energy consumption and costs. The ultrathin-film nature of zeolite nanosheets and their versatile pore structures provides great opportunities in desalination. To push forward the development of zeolite nanosheets for water desalination, nonequilibrium molecular dynamics simulations were carried out to systematically study zeolites as RO membranes and establish fundamental structure-performance relationships. We have identified that zeolite nanosheets can achieve a high salt rejection rate close to 100% while allowing nearly 2 orders of magnitude higher water permeability than currently available membranes. Moreover, the effects of the pore density, inclusion of cages, and free energy barrier on water permeability and salt rejection are unraveled, leading to important insights toward the rational design of novel zeolite membranes.

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Section: Introductionmentioning

confidence: 99%

Atomistic Understanding of Zeolite Nanosheets for Water Desalination

2017

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“…Currently, many efforts are made to develop new types of catalysts based on hierarchical zeolites in the HDC reaction. ,, Introducing mesopores into the zeolites or reducing the zeolite crystalline size can efficiently overcome the diffusion limitations and significantly accelerate the mass transfer to and away from the catalytic centers, thus reducing the possibility of secondary reactions which cause coke formation and catalyst deactivation . Therefore, catalyst supports with open hierarchical pore structures contribute to high catalytic activity.…”

Section: Applicationsmentioning

confidence: 99%

Hierarchically Structured Zeolites: From Design to Application

et al. 2020

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Hierarchical zeolites combine the intrinsic catalytic properties of microporous zeolites and the enhanced access and transport of the additional meso-and/or macroporous system. These materials are the most desirable catalysts and sorbents for industry and become a highly evolving field of important current interests. In addition to the enhanced mass transfer leading to high activity, selectivity, and cycle time, another essential merit of the hierarchical structure in zeolite materials is that it can significantly improve the utilization effectiveness of zeolite materials resulting in the minimum energy, time, and raw materials consumption. Substantial progress has been made in the synthesis, characterization, and application of hierarchical zeolites. Herein, we provide an overview of recent achievements in the field, highlighting the significant progress in the past decade on the development of novel and remarkable strategies to create an additional pore system in zeolites. The most innovative synthesis approaches are reviewed according to the principle, versatility, effectiveness, and degree of reality while establishing a firm link between the preparation route and the resultant hierarchical pore quality in zeolites. Zeolites with different hierarchically porous structures, i.e., micro-mesoporous structure, micromacroporous structure, and micro-meso-macroporous structure, are then analyzed in detail with concrete examples to illustrate their benefits and their fabrications. The significantly improved performances in catalytic, environmental, and biological applications resulting from enhanced mass transport properties are discussed through a series of representative cases. In the concluding part, we envision the emergence of "material-properties-by-quantitative and real rational design" based on the "generalized Murray's Law" that enables the predictable and controlled productions of bioinspired hierarchically structured zeolites. This Review is expected to attract important interests from catalysis, separation, environment, advanced materials, and chemical engineering fields as well as biomedicine for artificial organ and drug delivery systems.

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“…Utilizing the lower boiling point of the (shorter) cracked products to separate them out of a reaction mixture, process conditions can be found to minimize secondary reactions that lead to the formation of gasoline and gas, but this is effective only at low wax conversions over Pt on amorphous silica–alumina (ASA) . Recent advances in the control over noble-metal location as well as in the preparation of mesoporous zeolites , have demonstrated that catalyst improvement can lower the degree of secondary cracking for several model and real feeds. − Pure primary cracking, the breaking of only one carbon–carbon bond in the reactant, has been observed since the earliest description of n -hexadecane ( n -C 16 ) hydrocracking over Pt/ASA and subsequently in the ideal hydrocracking of n -C 16 over the more active large-pore Pt/Ca-Y zeolite . In ideal hydrocracking a strong (de)hydrogenation activity maintains a steady-state concentration of n -alkenes high enough to displace the alkylcarbenium ions from the acid sites through competitive adsorption.…”

Section: Introductionmentioning

confidence: 99%

Selective Formation of Linear Alkanes from n-Hexadecane Primary Hydrocracking in Shape-Selective MFI Zeolites by Competitive Adsorption of Water

2016

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MFI type zeolites have been known for decades for their strong tendency toward gas formation in hydrocracking. Our strategy for selectivity control in hydrocracking turns strong adsorption in micropores, responsible for secondary cracking, to an advantage. Enhancing diesel yield is a challenging goal in hydrocracking catalysis. Additionally, linear alkanes increase the diesel fuel cetane number and, consequently, effect a dramatic reduction in exhaust emissions. This study demonstrates for a set of Pt on mesoporous MFI zeolite catalysts that the gains in activity and selectivity attributed to enhanced mass transport are but modest by comparison to the effects of the competitive adsorption of water. Water suppresses secondary cracking, and primary cracking is now reported over MFI zeolites. Furthermore, competitive adsorption of water in shape-selective MFI zeolites facilitates desorption of the primary n-C16 cracking products and suppresses subsequent isomerization resulting in high yields of linear alkanes. The selectivity for linear alkanes from hydrocracking of n-hexadecane over Pt/MFI nanosheets reaches 80% at 80% conversion.

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Hierarchical porous nano-MFI zeolite-pillared montmorillonite clay synthesized by recrystallization for hydrocracking of residual oil

Cited by 7 publications

References 33 publications

Atomistic Understanding of Zeolite Nanosheets for Water Desalination

Atomistic Understanding of Zeolite Nanosheets for Water Desalination

Hierarchically Structured Zeolites: From Design to Application

Selective Formation of Linear Alkanes from n-Hexadecane Primary Hydrocracking in Shape-Selective MFI Zeolites by Competitive Adsorption of Water

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