Optimisation of the Fischer–Tropsch process using zeolites for tail gas separation

Perez-Carbajo, Julio; Gómez‐Álvarez, Paula; Bueno-Pérez, Rocío; Merkling, Patrick J.; Calero, Sofı́a

doi:10.1039/c3cp55255a

Cited by 13 publications

(13 citation statements)

References 27 publications

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“…The adsorption capacity of MFI-type zeolites is known to be cation-dependent in aluminum-containing frameworks. In a previous study, we have shown for some T-sites that this dependence lies not in the sodium cation distribution but in their number . In this study, we have expanded the scope to all T-sites.…”

Section: Mfi-type Structures With Sodium Cationsmentioning

confidence: 94%

Diffusion Patterns in Zeolite MFI: The Cation Effect

et al. 2018

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Zeolite MFI is one of the most important stable porous materials used in catalysis and separation processes. However, some fundamental properties remain in the dark, such as the effect of different aluminum distributions on diffusion. This work, through calculations on cation probability densities, guest energy profiles, and diffusion coefficients, provides a consistent picture of accessibility and mobility for two representative adsorbates, methane and carbon dioxide, and helps to explain the stark differences in diffusion behavior among varying aluminum distributions. A distribution was identified close to the practical limit of maximum aluminum substitution and sodium cation content that actually leads to a collapse in diffusion. For all aluminum distributions studied, the diffusion properties are closely linked to the number of cations. Compensating aluminum negative charge with divalent calcium instead of monovalent sodium increases methane but decreases carbon dioxide diffusion. With respect to increasing adsorbate loading, it induces a monotonous decrease in selfdiffusivities for all structures studied. This study highlights the desirability of controlling the aluminum substitution location and, more importantly, the fact that two heavily substituted MFI zeolites with identical composition reported in the literature may have very different diffusion properties.

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Section: Mfi-type Structures With Sodium Cationsmentioning

confidence: 94%

Diffusion Patterns in Zeolite MFI: The Cation Effect

et al. 2018

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“…The dual- adsorption ratios, or the stoichiometric adsorption properties of the material, play a critical role in the conversion efficiency. 42,43 Perez-Carbajo et al 44 recently demonstrated that IAST could reasonably describe the mixed adsorption of a ve-component mixture (CO 2 , CH 4 , CO, N 2 and H 2 ) within a range of zeolites (FAU, MFI, MOR and DDR) up to 100 bar. A large change in entropy and enthalpy upon adsorption will cause the reactants to bind into position and their internal bonds to become strained in preparation for reaction.…”

Section: Materials Propertiesmentioning

confidence: 99%

“…By considering solution thermodynamics the Ideal Adsorbed Solution Theory (IAST) was developed by Myers and Prausnitz to predict the adsorption equilibria of binary mixtures. 42,43 Perez-Carbajo et al 44 recently demonstrated that IAST could reasonably describe the mixed adsorption of a ve-component mixture (CO 2 , CH 4 , CO, N 2 and H 2 ) within a range of zeolites (FAU, MFI, MOR and DDR) up to 100 bar. In this study we also consider light gas adsorption within zeolites with minimal surface heterogeneity where IAST is applicable.…”

Section: Materials Propertiesmentioning

confidence: 99%

Towards computational design of zeolite catalysts for CO₂ reduction

et al. 2015

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Carbon dioxide, an energy waste by-product with significant environmental consequences can be utilized and converted into useful chemical products such as formic acid, formaldehyde, methanol or methane, but more energy and cost efficient catalytic processes are required. Here we develop the methodology for the intelligent selection of porous zeolites for dual-adsorption of hydrogen and carbon dioxide as templates for preparing the optimal catalytic environment for carbon dioxide reduction. Useful zeolite catalysts were computationally screened from over 300 thousand zeolite structures using a combination of molecular simulation and machine-learning techniques. Several of the top candidates were very promising energyefficient templates for catalysis with the potential to perform at 50% above conventional reactors. It is also found that an optimal cavity size of around 6 A is required to maximize the change in entropy-enthalpy upon adsorption with a maximum void space >30% to boost product formation per volume of material.

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“…Molecular simulations are an extensively used tool to predict the thermodynamic properties of a wide diversity of systems . Molecular simulations have been extensively used to predict the adsorption properties of hydrocarbons in zeolites − and other nanoporous materials. − Commonly, Monte Carlo simulations (MCs) in the grand-canonical ensemble (GCMC) can be used to compute sorbate loadings in a zeolite for different temperatures and pressures. − Several studies where MCs are used to study adsorption of aromatics in zeolites can be found in the literature. ,− Most molecular simulation studies of adsorption of hydrocarbons in zeolites have focused on adsorption from a vapor phase . This is due to the difficult insertion and deletion of molecules at conditions close to saturation, leading to inefficient simulations .…”

Section: Introductionmentioning

confidence: 99%

Competitive Adsorption of Xylenes at Chemical Equilibrium in Zeolites

et al. 2021

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The separation of xylenes is one of the most important processes in the petrochemical industry. In this article, the competitive adsorption from a fluid-phase mixture of xylenes in zeolites is studied. Adsorption from both vapor and liquid phases is considered. Computations of adsorption of pure xylenes and a mixture of xylenes at chemical equilibrium in several zeolite types at 250 °C are performed by Monte Carlo simulations. It is observed that shape and size selectivity entropic effects are predominant for small one-dimensional systems. Entropic effects due to the efficient arrangement of xylenes become relevant for large one-dimensional systems. For zeolites with two intersecting channels, the selectivity is determined by a competition between enthalpic and entropic effects. Such effects are related to the orientation of the methyl groups of the xylenes. m -Xylene is preferentially adsorbed if xylenes fit tightly in the intersection of the channels. If the intersection is much larger than the adsorbed molecules, p -xylene is preferentially adsorbed. This study provides insight into how the zeolite topology can influence the competitive adsorption and selectivity of xylenes at reaction conditions. Different selectivities are observed when a vapor phase is adsorbed compared to the adsorption from a liquid phase. These insight have a direct impact on the design criteria for future applications of zeolites in the industry. MRE-type and AFI-type zeolites exclusively adsorb p -xylene and o -xylene from the mixture of xylenes in the liquid phase, respectively. These zeolite types show potential to be used as high-performing molecular sieves for xylene separation and catalysis.

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Optimisation of the Fischer–Tropsch process using zeolites for tail gas separation

Cited by 13 publications

References 27 publications

Diffusion Patterns in Zeolite MFI: The Cation Effect

Diffusion Patterns in Zeolite MFI: The Cation Effect

Towards computational design of zeolite catalysts for CO₂ reduction

Competitive Adsorption of Xylenes at Chemical Equilibrium in Zeolites

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Optimisation of the Fischer–Tropsch process using zeolites for tail gas separation

Cited by 13 publications

References 27 publications

Diffusion Patterns in Zeolite MFI: The Cation Effect

Diffusion Patterns in Zeolite MFI: The Cation Effect

Towards computational design of zeolite catalysts for CO2 reduction

Competitive Adsorption of Xylenes at Chemical Equilibrium in Zeolites

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Product

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Towards computational design of zeolite catalysts for CO₂ reduction