Passivated Surface of High Aluminum Containing ZSM-5 by Silicalite-1: Synthesis and Application in Dehydration Reaction

Giordano, G.; Migliori, Massimo; Ferrarelli, Giorgia; Giorgianni, Gianfranco; Dalena, Francesco; Peng, Peng; Debost, Maxime; Boullay, Philippe; Liu, Zhen; Guo, Hailing; Zhang, Yan; Mintova, Svetlana

doi:10.1021/acssuschemeng.1c07198

Cited by 12 publications

(5 citation statements)

References 58 publications

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“…While the production of metal-oxide@zeolite core–shells is generally exploited when acid–base function is required to avoid the sintering of the metal catalyst and its deactivation, in recent years the synthesis of composite materials characterized by both a zeolitic core and a zeolitic shell has been widely employed to neutralize external strong acid sites or to achieve a gradient of distribution of zeolite acid sites. In particular, growing a nonacidic zeolite shell, such as silicalite-1, on the surface of the starting core allows the passivation of the external strong acidity and meanwhile preserves the catalytic activity without limiting the accessibility of internal acid sites . ZSM-5@silicalite-1 composites have been synthesized using different techniques and employed for various applications.…”

Section: Zeolite Surface Passivation and Catalysismentioning

confidence: 99%

“…In particular, growing a nonacidic zeolite shell, such as silicalite-1, on the surface of the starting core allows the passivation of the external strong acidity and meanwhile preserves the catalytic activity without limiting the accessibility of internal acid sites. 6 ZSM-5@silicalite-1 composites have been synthesized using different techniques and employed for various applications. This approach usually consists of two steps: first the core crystals, eventually pretreated, are placed in contact with the silicalite-1 precursor solution, and the hydrothermal crystallization of the shell is carried out during the second step.…”

Section: Zeolite Surface Passivation and Catalysismentioning

confidence: 99%

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Recent Trends in Tailoring External Acidity in Zeolites for Catalysis

Ferrarelli,

Migliori,

Catizzone

2024

ACS Omega

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Zeolites are crystalline aluminosilicates with well-defined microporous structures that have found several applications in catalysis. In recent years, great effort has been devoted to defining strategies aimed at tuning structural and acidity properties to improve the catalytic performance of zeolites. Depending on the zeolitic structure, the acid sites located inside the crystals catalyze reactions by exploiting the internal channel shape-selectivity. In contrast, strong acid sites located on the external surface do not offer the possibility to control the size of molecules involved in the reactions. This aspect generally leads to a loss of selectivity toward desired products and to the uncontrolled production of coke. Passivating surface acidity is a promising way to overcome deactivation issues and to enhance the catalytic performance of zeolites. This Mini-Review aims to provide, for the first time, a complete overview of the techniques employed in recent years to neutralize strong external acid sites. Both chemical and liquid vapor deposition of silicates have been widely employed to passivate the external surface acidity of zeolites. In recent years, the epitaxial growth of layers of aluminum-free zeolite, e.g., silicalite-1, over the surface of the acidic zeolite has been proposed as a new approach to neutralize strong external acid sites controlling diffusional phenomena. NH 3 -TPD, FT-IR, SEM-EDX, and other techniques have been used to provide information about the level of control of the external strong acidity of passivated zeolites. In this Mini-Review, both passivation treatments and characterization techniques are compared and advantages and disadvantages deeply discussed to elucidate the effect of passivation procedures on physical features and especially the catalytic behavior.

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Section: Zeolite Surface Passivation and Catalysismentioning

confidence: 99%

Section: Zeolite Surface Passivation and Catalysismentioning

confidence: 99%

Recent Trends in Tailoring External Acidity in Zeolites for Catalysis

Ferrarelli,

Migliori,

Catizzone

2024

ACS Omega

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“…Shape-selective catalysts such as ZSM-5, zeolites, and silicalite-1 are widely used in the petroleum industry for isomerization of hydrocarbons, dehydration reactions and production of synthetic gasoline, owing to their uniform pore structure, high thermal stability, and high concentration of active sites. − Huang and Sadow recently reported the pore template effect on the overall distribution of products in the hydrogenolysis of polyolefins using a platinum nanoparticle catalyst embedded in mesoporous silica shell supported on a solid silica sphere, mSiO 2 /Pt-Size/SiO 2 . We envisioned that developing single-site metal catalysts within porous materials having uniform and tunable pores would better control the C–C bond cleavage and product selectivity during the hydrogenolysis of polyolefins via shape-selective catalysis.…”

Section: Introductionmentioning

confidence: 99%

Isoreticular Metal–Organic Frameworks Confined Mononuclear Ru-Hydrides Enable Highly Efficient Shape-Selective Hydrogenolysis of Polyolefins

Chauhan,

Antil,

Rana

et al. 2023

JACS Au

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Upcycling nonbiodegradable plastics such as polyolefins is paramount due to their ever-increasing demand and landfills after usage. Catalytic hydrogenolysis is highly appealing to convert polyolefins into targeted value-added products under mild reaction conditions compared with other methods, such as high-temperature incineration and pyrolysis. We have developed three isoreticular zirconium UiO-metal–organic frameworks (UiO-MOFs) node-supported ruthenium dihydrides (UiO-RuH 2 ), which are efficient heterogeneous catalysts for hydrogenolysis of polyethylene at 200 °C, affording liquid hydrocarbons with a narrow distribution and excellent selectivity via shape-selective catalysis. UiO-66-RuH 2 catalyzed hydrogenolysis of single-use low-density polyethylene (LDPE) produced a C12 centered narrow bell-shaped distribution of C8–C16 alkanes in >80% yield and 90% selectivity in the liquid phase. By tuning the pore sizes of the isoreticular UiO-RuH 2 MOF catalysts, the distribution of the products could be systematically altered, affording different fuel-grade liquid hydrocarbons from LDPE in high yields. Our spectroscopic and theoretical studies and control experiments reveal that UiO-RuH 2 catalysts enable highly efficient upcycling of plastic wastes under mild conditions owing to their unique combination of coordinatively unsaturated single-site Ru-active sites, uniform and tunable pores, well-defined porous structure, and superior stability. The kinetics and theoretical calculations also identify the C–C bond scission involving β-alkyl transfer as the turnover-limiting step.

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“…A ZSM-5 molecular sieve is a widely used microporous substance. Due to its excellent properties, it has been studied by many experts [ 1 , 2 , 3 , 4 ]. The special framework structure of the ZSM-5 molecular sieve provides it with unique shape selectivity, thermal stability, and acid resistance [ 5 , 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Preparation of a High-Silicon ZSM-5 Molecular Sieve Using Only Coal Gangue as the Silicon and Aluminum Sources

Zheng

Zhou

et al. 2023

Materials

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The traditional preparation of ZSM-5 molecular sieves relies on chemical reagents to provide silicon and aluminum sources, which are limited as raw materials and cannot be commonly used in production practice. Using coal gangue as the raw material and using medium-temperature chlorination roasting and the pressure acid leaching process to control the silicon–aluminum ratio [n(Si/Al)] of coal gangue, a ZSM-5 molecular sieve was prepared using the alkali melting hydrothermal method. The pressure acid leaching process solved the limitation that kaolinite and mica cannot simultaneously be activated. Under optimal conditions, the n(Si/Al) of the coal gangue increased from 6.23 to 26.14 and complied with the requirements for the synthesis n(Si/Al) of a ZSM-5 molecular sieve. The effect of n(Si/Al) on the preparation of the ZSM-5 molecular sieve was studied. Finally, spherical granular ZSM-5 molecular sieve material with a microporous specific surface area of 169.6329 m2/g, an average pore diameter of 0.6285 nm, and a pore volume of 0.0988 cm3/g was prepared. Providing ideas for the high-value utilization of coal gangue, it is significant for solving the problem of coal gangue solid waste, as well as the problem of ZSM-5 molecular sieve feed stock.

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Passivated Surface of High Aluminum Containing ZSM-5 by Silicalite-1: Synthesis and Application in Dehydration Reaction

Cited by 12 publications

References 58 publications

Recent Trends in Tailoring External Acidity in Zeolites for Catalysis

Recent Trends in Tailoring External Acidity in Zeolites for Catalysis

Isoreticular Metal–Organic Frameworks Confined Mononuclear Ru-Hydrides Enable Highly Efficient Shape-Selective Hydrogenolysis of Polyolefins

Preparation of a High-Silicon ZSM-5 Molecular Sieve Using Only Coal Gangue as the Silicon and Aluminum Sources

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