Synthesis of FAU(Y)- and MFI(ZSM5)-nanosized crystallites for catalytic cracking of 1,3,5-triisopropylbenzene

Morales-Pacheco, P.; Dominguez, J. M.; Bucio, L.; Álvarez, F.; Sedrán, Ulises; Falco, Marisa

doi:10.1016/j.cattod.2010.07.005

Cited by 51 publications

(33 citation statements)

References 47 publications

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“…For example, accessibility in FCC matrices [23], impact of the different size in Y zeolite particles [4,5,24], and various issues in acidic catalysts [10,21,25]. Most important positive characteristics are that the molecules' critical diameter is significantly larger than the Y zeolite pore size (7.4 Å ), and its reaction can be tracked relatively easily, since the cracking reaction follows a basically sequential path of the scission of the side alkyl chains while the benzenic ring keeps essentially unaltered [4,21,23].…”

Section: Introductionmentioning

confidence: 99%

Impact of the Desilication Treatment of Y Zeolite on the Catalytic Cracking of Bulky Hydrocarbon Molecules

2015

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Mesoporosity was induced on a USY zeolite by means of an alkaline leaching process. Samples were immersed in 0.05, 0.10 and 0.20 M NaOH solutions during 15 min at room temperature and then were exchanged with NH 4? ions and calcined to yield the acid forms. The formation of mesopores with size ranging from 20 to 100 Å increased with the concentration of NaOH. The modified zeolites were used at 30 wt% to formulate cracking catalysts with an inert SiO 2 matrix. The catalytic performance of these catalysts in the conversion of 1,3,5-tri-isopropylbenzene was evaluated in a batch, fluidized bed reactor at 450, 500 and 530°C, with a catalyst to oil relationship of 4.7 and contact times up to 16 s. The catalysts with the modified zeolites were more active in the cracking of these bulky molecules than the one with the parent, unmodified zeolite; moreover, the selectivity to the products of primary cracking reactions increased. These results reveal an enhanced diffusion of the reactant molecules to the zeolite active sites and of the products out of the catalyst particles.

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Section: Introductionmentioning

confidence: 99%

Impact of the Desilication Treatment of Y Zeolite on the Catalytic Cracking of Bulky Hydrocarbon Molecules

2015

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“…These molecules are small enough to penetrate the micropores system to undergo further cracking at reaction conditions, henceforth, the products distribution reflect the effect out of diffusion rather than accessibility 40 . In ZSM-11-H, as the diffusion pathway has been shortened as the crystal size is reduced, more primary product 1,3-diisopropylbenzene has been converted into cumene and benzene, resulting in a detectable increase in their selectivities (Table 4).…”

Section: Acid Properties and Catalytic Performancementioning

confidence: 99%

A solvent evaporation route towards fabrication of hierarchically porous ZSM-11 with highly accessible mesopores

Song

Liu

et al. 2015

RSC Adv.

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Abstract:A route to generate hierarchically porous zeolite ZSM-11 (MEL) has been paved via solvent evaporation induced self-assembly to produce a dry gel and its subsequent transformation into zeolite by steam-assisted-crystallization. The structure evolution has been monitored to shed light on the structure evolution during crystallization process.Measurements such as XRD, SEM, TEM, N 2 -physisorption, and TEM for inverse replica of

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“…[1][2][3] Tal modificação confere significativas mudanças nas propriedades das zeólitas, caracterizando-se principalmente pelo aumento expressivo em sua área externa e acessibilidade aos sítios catalíticos. 4 Por consequência, diferentes performances são alcançadas, mesmo em aplicações tradicionais como em separação e catálise.…”

Section: Introductionunclassified

“…4 Por consequência, diferentes performances são alcançadas, mesmo em aplicações tradicionais como em separação e catálise. 1,5 Apesar do grande potencial para o uso em reações industrialmente importantes, poucos estudos têm sido realizados com peneiras moleculares microporosas possuindo propriedades básicas. Entre elas estão as condensações de Claisen, de Knoevenagel, aldólicas, e a transesterificação.…”

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Catalytic Properties of Nanometric Zeolite X Containing Methylammonium Cations

Vicente¹,

Lima²,

Cardoso³

2016

Química Nova

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publicado na web em 06/05/2016 CATALYTIC PROPERTIES OF NANOMETRIC ZEOLITE X CONTAINING METHYLAMMONIUM CATIONS. The reduction of zeolite particle is one of the main features currently searched; it is due to the catalytic gains that these materials come in some reactions. In this work two faujasite zeolites of type X were evaluated, a micrometer and nanometric. Zeolites in sodium form were exchanged ionically with methylammonium cations. These materials were evaluated as catalysts in the Knoevenagel condensation reaction. Steric impediments restricted the ion exchange in the micrometer zeolite and have become more predominant due to the increase in the volume of cations. In nanometric sample such impediments were less evident due to the reduction of the particles provide greater accessibility to exchangers cations to inaccessible sodium in micrometer zeolite. The best catalytic performances were achieved with zeolites containing the monomethylammonium cation. The increased of the accessibility and diffusion of the reactants and products through the pores of the nanometric zeolite provided the best butyraldehyde conversions independent the exchanger cation.Keywords: X Zeolite; nanoparticles; ion exchange; base catalysis; Knoevenagel condensation. INTRODUÇÃOAtualmente diversas pesquisas visam a redução do tamanho das partículas zeolíticas da escala micrométrica para nanométrica.1-3 Tal modificação confere significativas mudanças nas propriedades das zeólitas, caracterizando-se principalmente pelo aumento expressivo em sua área externa e acessibilidade aos sítios catalíticos. 4 Por consequência, diferentes performances são alcançadas, mesmo em aplicações tradicionais como em separação e catálise. 1,5 Apesar do grande potencial para o uso em reações industrialmente importantes, poucos estudos têm sido realizados com peneiras moleculares microporosas possuindo propriedades básicas. Entre elas estão as condensações de Claisen, de Knoevenagel, aldólicas, e a transesterificação. Hoje em dia, entre todas as aplicações industriais de catalisadores sólidos ácidos, básicos e bifuncionais, apenas 8% dos processos são catalisados por materiais com propriedades básicas. 6 A basicidade das zeólitas está relacionada com os ânions oxigênio pertencentes à sua rede. Os sítios básicos estão associados aos átomos de oxigênio estruturais, localizados próximos aos cátions compensadores de cargas.7 Esses ânions oxigênio são gerados pela inserção de átomos de alumínio à rede zeolítica. Por serem estruturais, o número de sítios básicos é igual ao número de átomos de alumínio na estrutura. Então a concentração de alumínio estrutural não está ligada somente a distribuição de cargas, mas também ao número de sítios básicos presentes na zeólita. A força desses sítios depende principalmente da acidez do cátion compensador de carga, mas também do teor de alumínio na rede zeolítica. 7,8 A troca iônica é uma propriedade das zeólitas associada à presença dos cátions que compensam a carga negativa relacionada aos tetraedros [AlO 4 ] -estruturais. 4,7...

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Synthesis of FAU(Y)- and MFI(ZSM5)-nanosized crystallites for catalytic cracking of 1,3,5-triisopropylbenzene

Cited by 51 publications

References 47 publications

Impact of the Desilication Treatment of Y Zeolite on the Catalytic Cracking of Bulky Hydrocarbon Molecules

Impact of the Desilication Treatment of Y Zeolite on the Catalytic Cracking of Bulky Hydrocarbon Molecules

A solvent evaporation route towards fabrication of hierarchically porous ZSM-11 with highly accessible mesopores

Catalytic Properties of Nanometric Zeolite X Containing Methylammonium Cations

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