Sorption kinetics of linear paraffins in zeolite BEA nanocrystals

Lima, Patrícia M.; Gonçalves, Caroline Vieira; Cavalcante, Célio L.; Cardoso, Dilson

doi:10.1016/j.micromeso.2009.04.024

Cited by 5 publications

(4 citation statements)

References 16 publications

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“…There are however some distinct differences between the solution for a sphere and a slab geometry. These have been used to determine the diffusion path in nanoporous materials (Vidoni and Ruthven 2012a;Cavalcante et al 1997;Lima et al 2008;Huang et al 2010).…”

Section: Distinguishing the Diffusion Pathmentioning

confidence: 99%

The zero length column technique to measure adsorption equilibrium and kinetics: lessons learnt from 30 years of experience

Brandani

Mangano

2020

Adsorption

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The zero length column technique has been developed over the past 30 years as a versatile experimental method to measure adsorption equilibrium and kinetics. In this review we discuss in detail the theory that forms the basis for the technique in order to understand how to design and operate efficiently a system. Experimental checks that should be performed to ensure the correct interpretation of the dynamic response are presented and examples are used to identify how to avoid major errors in determining diffusion time constants. The review concludes with an overview of all experimental studies available in the literature to date and a set of recommendations that should help improve the standard in the reported equilibrium and kinetic properties.

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Section: Distinguishing the Diffusion Pathmentioning

confidence: 99%

The zero length column technique to measure adsorption equilibrium and kinetics: lessons learnt from 30 years of experience

Brandani

Mangano

2020

Adsorption

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“…However, their nanometric size makes difficult their recovery and manipulation after catalytic reaction. Furthermore, the tendency of zeolites nanoparticles to aggregate during synthesis and/or upon drying and calcination usually results in a partial loss of external surface area, and as a consequence, reduces the positive impact of their nanometric crystallite size on the diffusion of reactants [4].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of supported ZSM-5 nanoparticles

Moussa

Borghol

et al. 2019

Microporous and Mesoporous Materials

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The influence of the support on the nucleation of ZSM-5 nanoparticles has been studied for three supports: γ-alumina, zirconia and carbon nanotubes (CNT). While zeolite nucleation was suppressed in presence of alumina and strongly delayed in presence of zirconia, it occurred without delay in presence of CNT. These differences are explained by the partial dissolution of the support (for alumina and zirconia supports) that modify the composition of the zeolite nucleation solution. For the CNT/zeolite sample, the obtained composite contains about 60 wt% of zeolite and develops a surface area of 776 m 2 .g-1 .

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“…Among all zeolites, the BEA framework structure (12 MR, 6.6 × 6.7** ↔ 5.6 × 5.6*) is one of the most easily synthesized at the nanometric scale. , It is also well-known that BEA nanocrystals tend to aggregate forming larger clusters (>1 μm), which were proven to generate diffusion limitations . Our previous study has dealt with the effect of this nanocrystalline aggregation on the sorption kinetics of isobutane using the reverse-flow gas chromatographic (RF-GC) technique .…”

Section: Introductionmentioning

confidence: 99%

“…4,5 It is also well-known that BEA nanocrystals tend to aggregate forming larger clusters (>1 μm), 6 which were proven to generate diffusion limitations. 7 Our previous study has dealt with the effect of this nanocrystalline aggregation on the sorption kinetics of isobutane using the reverse-flow gas chromatographic (RF-GC) technique. 8 Initially developed by Katsanos,9,10 this technique measures physicochemical phenomena rates, not only initially, but over an extended time period, and allows, in conjunction with numerical computation, to calculate further information, as local monolayer capacities, probability density functions, and effective/surface diffusion coefficients.…”

Section: ■ Introductionmentioning

confidence: 99%

Interactions of H₂on the Isobutane Adsorption over Bifunctional Catalyst PtHBEA Revealed by Reversed-Flow Inverse Gas Chromatography

et al. 2015

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The interactions of isobutane (i-C 4 ) over a bifunctional catalyst PtHBEA are investigated at 343 K in both neutral (helium) and reactive (hydrogen) atmospheres. Reverse flow inverse gas chromatography, used in conjunction with numerical computation, allowed the determination of physicochemical quantities such as local monolayer capacities, probability density functions, and diffusion coefficients in a time-resolved way. The energetic heterogeneity is modified by the dissociative adsorption of hydrogen over the platinum particles. Effective diffusion coefficient of isobutane is mainly affected by the concentration of protonic sites, while the surface diffusion involves more complex phenomena related to the platinum/zeolite interactions and the hydrogen spillover. ■ INTRODUCTIONHydroisomerization on bifunctional catalysts is a key refinery process converting heavy petroleum fractions, as well as renewable hydrocarbons, into high value lubricants and fuels. In the field of long chain n-paraffins hydroconversion, maximizing the yield of n-alkanes in skeletal isomers is an important challenge. For this purpose, typical catalysts are bifunctional, associating a noble metal (e.g., Pt or Pd) and an acidic support. 1 The rational design of bifunctional redox-acid refining catalysts demands the definition of the parameters governing their behavior and the knowledge of their quantitative effect. This is what has been successfully made on isomerization dewaxing Pt-Hzeolite catalysts. n-Alkane hydroisomerization involves seven successive steps: 2,3 three chemical ones, dehydrohydrogenation on the Pt sites, and alkene skeletal isomerization on the protonic acid sites (H + ) and four diffusion ones, in gas phase (alkanes) and along the zeolite micropores (alkenes) from the Pt to the H + sites and vice versa. Moreover, since the reaction takes place under a pressure hydrogen atmosphere, it is an accepted fact that the metallic sites produce hydrogen radical species that spillover (HSP) to neighboring surfaces. These species could impact the surface diffusion of adsorbed species and consequently impact on the reaction performances.Among all zeolites, the BEA framework structure (12 MR, 6.6 × 6.7** ↔ 5.6 × 5.6*) is one of the most easily synthesized at the nanometric scale. 4,5 It is also well-known that BEA nanocrystals tend to aggregate forming larger clusters (>1 μm), 6 which were proven to generate diffusion limitations. 7 Our previous study has dealt with the effect of this nanocrystalline aggregation on the sorption kinetics of isobutane using the reverse-flow gas chromatographic (RF-GC) technique. 8 Initially developed by Katsanos,9,10 this technique measures physicochemical phenomena rates, not only initially, but over an extended time period, and allows, in conjunction with numerical computation, to calculate further information, as local monolayer capacities, probability density functions, and effective/surface diffusion coefficients. 11 The main goal of this study intends to show the influence of a reactive atmosphere...

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Sorption kinetics of linear paraffins in zeolite BEA nanocrystals

Cited by 5 publications

References 16 publications

The zero length column technique to measure adsorption equilibrium and kinetics: lessons learnt from 30 years of experience

The zero length column technique to measure adsorption equilibrium and kinetics: lessons learnt from 30 years of experience

Synthesis of supported ZSM-5 nanoparticles

Interactions of H₂on the Isobutane Adsorption over Bifunctional Catalyst PtHBEA Revealed by Reversed-Flow Inverse Gas Chromatography

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Sorption kinetics of linear paraffins in zeolite BEA nanocrystals

Cited by 5 publications

References 16 publications

The zero length column technique to measure adsorption equilibrium and kinetics: lessons learnt from 30 years of experience

The zero length column technique to measure adsorption equilibrium and kinetics: lessons learnt from 30 years of experience

Synthesis of supported ZSM-5 nanoparticles

Interactions of H2on the Isobutane Adsorption over Bifunctional Catalyst PtHBEA Revealed by Reversed-Flow Inverse Gas Chromatography

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Interactions of H₂on the Isobutane Adsorption over Bifunctional Catalyst PtHBEA Revealed by Reversed-Flow Inverse Gas Chromatography