Effect of desilication on the textural properties, acidity and catalytic activity of zeolite ZSM-23 synthesized with different structure-directing agents

Silva, Bruno J. B.; Sousa, Lenivaldo V.; Sarmento, Lais R.A.; Carvalho, Rosângela Pedrosa; Quintela, Paulo Henrique Leite; Pacheco, José Geraldo A.; Fréty, R.; Silva, Antônio Osimar Sousa da

doi:10.1016/j.micromeso.2019.109647

Cited by 20 publications

(10 citation statements)

References 60 publications

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“…ZSM-23 showed promising applications in the isomerization of butene and catalytic cracking reactions. 27 − 30 Numerous OSDAs have been employed in the synthesis of MTT zeolite, including N , N -dimethylformamide, 5 , 31 isopropylamine (IPA), 28 , 31 ethylene glycol, 31 and pyrrolidine (PY). 32 , 33 Moreover, Moini et al have used a variety of linear-type diquaternary ammonium, including Me6-diquat-5, Me6-diquat-6, Me6-diquat-11, and Me6-diquat-12, to prepare ZSM-23 zeolite.…”

Section: Introductionmentioning

confidence: 99%

“…The MTT zeolite, first reported as ZSM-23, possesses noninterconnected 10-MR one-dimensional channels with drop-shaped pore openings of 0.52 × 0.45 nm in diameter. ZSM-23 showed promising applications in the isomerization of butene and catalytic cracking reactions. − Numerous OSDAs have been employed in the synthesis of MTT zeolite, including N , N -dimethylformamide, , isopropylamine (IPA), , ethylene glycol, and pyrrolidine (PY). , Moreover, Moini et al have used a variety of linear-type diquaternary ammonium, including Me6-diquat-5, Me6-diquat-6, Me6-diquat-11, and Me6-diquat-12, to prepare ZSM-23 zeolite . Studies on the preparations of zeolites using quaternary ammoniums with carbon chain lengths greater than 6 are rather limited, the reason of which may lie in the weak structure-directing ability of this family of compounds .…”

Section: Introductionmentioning

confidence: 99%

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Syntheses of MTT-Type Zeolites with the Presence of Both Octyltrimethylammonium Chloride and SFE-Type Zeolite Seeds

Liu

et al. 2021

ACS Omega

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Structure-directing agents (SDAs) play important roles in directing the formation of specific zeolite frameworks. Mechanisms and working hypothesis were proposed for understanding how SDAs work during the crystallization of zeolites. The lately reported cooperative structure-directing effect based on the investigation into the synthetic system containing both seed and organic species is one of them and is believed to be effective for synthesizing zeolites which are difficult to access or with novel structures. However, more examples are still needed to support the thesis. Herein, we report for the first time the syntheses of MTT -type zeolites with the simultaneous presences of octyltrimethylammonium chloride (OTMAC) and SFE zeolite seeds in the borosilicate system. SFE borosilicate zeolites serve as exotic seeds for the crystallization of MTT -type zeolites and together with OTMAC play cooperative structure-directing roles. Besides, Al,B- MTT and heteroatom (Zr, V, and Fe)-incorporated MTT -type zeolites were directly synthesized with the introduction of metal sources into the borosilicate system. Physicochemical properties of the obtained MTT zeolites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N 2 physisorption, NH 3 -TPD, 27 Al NMR, 13 C NMR, 11 B NMR, UV–visible spectroscopy, and UV Raman spectroscopy. The herein-reported phenomenon provides an example to better understand the mechanism of zeolite crystallization, and the synthesized zeolites may act as promising catalytic materials in several organic reactions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Syntheses of MTT-Type Zeolites with the Presence of Both Octyltrimethylammonium Chloride and SFE-Type Zeolite Seeds

Liu

et al. 2021

ACS Omega

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“…The Z22-Me-CS and Z22-HS40-Des samples initially provided lower conversions, showing greater stability during the reaction time. The Z22-Me-CS sample, despite having strong acid site density similar to Z22-ADE and Z22-Brij93, does not exhibited the same catalytic activity behavior, indicating that for these one-dimensional materials the acidity is related not only to the SiO2/Al2O3 ratio, but also with the coordination of aluminum atoms in the crystal structure (Silva, et al, 2019).The lower activity showed by the Z22-HS40 sample is related to a lower density of strong acid sites, resulting from a certain degree of dealuminization of the structure after desilication (Verboekend, et al, 2011). On the other hand, the generation of mesopores led to a greater stability and lower coke content compared to the microporous zeolites.…”

Section: Catalytic Performancementioning

confidence: 98%

“…The total pore volume (VTotal) was measured using the single-point BET method (Dollimore & Spooner, 1974) at P/P0 = 0.995. The mesoporous volume (VMeso) was obtained by the difference between the total pore volume and the micropore volume (VMeso = VTotal -VMicro) (Silva, et al, 2019). The pore size distribution was obtained from the adsorption branch of the isotherm by the BJH method (Barrett, E. P., Joyner, L. G. & Halenda, 1951).…”

Section: Characterizationmentioning

confidence: 99%

“…Therefore, different studies have been carried out with the aim of improving the textural properties of these materials with the introduction of a secondary porosity (Verboekend, et al, 2011;Dyballa, et al, 2016;Wang et al,2019). Silva et al (2019) obtained the micro-mesoporous ZSM-22 by adding nanometric silica previously silanized with trimethoxyphenylsilane to the reaction mixture, followed by desilication. The samples showed a pore size distribution in the range of mesopores between 40 and 60 nm.…”

Section: Introductionmentioning

confidence: 99%

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Different approaches to the synthesis of ZSM-22 zeolite with application in n-heptane cracking

Júnior

Ribeiro

Silva

et al. 2022

RSD

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The synthesis of ZSM-22 zeolite has been extensively studied due to its properties of form selectivity, acidity and hydrothermal stability, which is applied in important reactions in the areas of petroleum refining and petrochemicals. In view of this, the present work studied different approaches of synthesis of ZSM-22 using: 1-diaminohexane as a structure directing agent, (ii) methanol and seed crystals, (iii) aging of the synthesis gel with addition of polymer, surfactant and silane and (iv) starch, calcium carbonate and silanized silica with subsequent desilication. Thus, the effects of these methodologies on the textural properties, acidity and catalytic activity of the zeolites obtained were evaluated. The samples were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, scanning electron microscopy (SEM), ammonia desorption at programmed temperature (NH3-TPD) and thermal analysis (TG/DTG). The catalytic activity and selectivity of the catalysts were evaluated in the model catalytic cracking reaction of n-heptane at 650 °C for 180 min. The synthesis route using methanol and seed crystals allowed obtaining ZSM-22 in 3 h of crystallization, drastically reducing the synthesis time compared to other methodologies. Despite this, the use of 1-diaminohexane led to the obtaining of zeolite with textural properties, acidity and catalytic activity superior to the other samples. The generation of mesoporosity was obtained through the use of silanized silica and subsequent desilication, leading to greater catalytic stability and less deactivation by coke. All catalysts showed similar selectivity to the formation of compounds in the range C2 to C4.

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

et al. 2020

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Zeolites are highly crystalline aluminosilicates with welldefined pores that are constructed of SiO 2 and AlO 4 tetrahedra. These tetrahedra can be linked together in different unique ways to form various materials with a specific topology. [1] According to the International Zeolite Association (IZA), more than 250 different topologies, which are all assigned with a three-letter code, have been identified. [2] The micropores in zeolites are typically constructed from 8, 10, or 12 tetrahedral atoms

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Effect of desilication on the textural properties, acidity and catalytic activity of zeolite ZSM-23 synthesized with different structure-directing agents

Cited by 20 publications

References 60 publications

Syntheses of MTT-Type Zeolites with the Presence of Both Octyltrimethylammonium Chloride and SFE-Type Zeolite Seeds

Syntheses of MTT-Type Zeolites with the Presence of Both Octyltrimethylammonium Chloride and SFE-Type Zeolite Seeds

Different approaches to the synthesis of ZSM-22 zeolite with application in n-heptane cracking

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

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