Numerical Simulation of Hindered Diffusion in γ -Alumina Catalyst Supports

Mahato

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

et al. 2021

The present study focuses on the catalytic conversion of syngas (CO + H2) through Fischer–Tropsch (FT) route using two identically prepared 0.1 wt.% palladium promoted Mesoporous Alumina (MA) and SBA–15 supported Co (15 wt.%) catalysts. The Fischer–Tropsch activity is performed in a fixed bed tubular reactor at temperature 220 °C and pressure 30 bar with H2/CO ratio ~2 having Gas Hourly Space Velocity (GHSV) of 500 h−1. Detail characterizations of the catalysts are carried out using different analytical techniques like N2 adsorption-desorption, Temperature-programmed reduction with hydrogen (H2-TPR), Temperature-programmed desorption with NH3 (NH3-TPD), X-Ray Diffraction (XRD), and Transmission Electron Microscopy (TEM). The results show that the SBA–15 supported catalyst exhibits higher C6–C12 selectivity (57.5%), and MA supported catalyst facilitates the formation of higher hydrocarbons (C13–C20) having a selectivity of 46.7%. This study attributes the use of both the support materials for the production of liquid hydrocarbons through FT synthesis.

Section: Introductionmentioning

confidence: 99%

Fischer–Tropsch synthesis over Pd promoted cobalt based mesoporous supported catalyst

Mahato

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

et al. 2021

“…Also, FFT-based methods were applied to compute the through-thickness conductivity of heterogeneous plates [204] and for an inverse reconstruction of the local conductivity [205]. Furthermore, extensions to compute Fickian diffusion [206] and ionic conductivity [207] were reported, as were applications to the effective conductivity and diffusivity of porous carbon electrodes [208], the electronic conductivity of lithium ion positive electrodes [209] and the conductivity of solid oxide fuel cell anodes [210].…”

Section: Conductivity and Diffusivitymentioning

confidence: 99%

A review of nonlinear FFT-based computational homogenization methods

Schneider

2021

Acta Mech

125

Since their inception, computational homogenization methods based on the fast Fourier transform (FFT) have grown in popularity, establishing themselves as a powerful tool applicable to complex, digitized microstructures. At the same time, the understanding of the underlying principles has grown, in terms of both discretization schemes and solution methods, leading to improvements of the original approach and extending the applications. This article provides a condensed overview of results scattered throughout the literature and guides the reader to the current state of the art in nonlinear computational homogenization methods using the fast Fourier transform.

“…PFG-NMR experiments have been performed as described by Wang et al 19 . A single extrudate is placed in a 5 mm diameter tube and immersed in 10% deuterated toluene.…”

Section: Pfg-nmr Experimentsmentioning

confidence: 99%

Tortuosity and mass transfer limitations in industrial hydrotreating catalysts: effect of particle shape and size distribution

Kolitcheff

Jolimaître

Hugon

et al. 2018

Catal. Sci. Technol.

The tortuosity factor of γ-alumina supports and catalysts used in hydrotreating applications was evaluated in liquid phase with three different techniques: Pulse Field Gradient-NMR (PFG-NMR), Inverse Liquid Chromatography (ILC) and catalytic experiments in a batch reactor. In order to satisfy the specific experimental constraints associated to each technique, tortuosity factor values were evaluated in a wide range of operating conditions: temperature was varied from 25°C to 340°C, catalyst particles were used as-synthesized (trilobe extrudates) or crushed, the liquid composition was either pure toluene, n-heptane/squalane mixtures, or squalane/2,5-bis-(octadecyl)thiophene mixtures. It is demonstrated that not taking into account both the shape factor and the size distribution of the particles can lead to significant errors on the tortuosity factor value. For both parameters, the optimal mean spherical radius depends on the contribution of internal diffusion to the overall performance. When internal diffusion is the limiting step, a new expression for the mean radius of distributed particle is proposed and validated by comparison between ILC and PFG-NMR results. This expression is transposable to any catalytic system, making it possible to measure tortuosity factors using either microscopic or macroscopic methodologies. Moreover, the tortuosity factors obtained with ILC and NMR are in good agreement with the one estimated from the catalytic experiments, showing that mass transfer parameters can be extrapolated from non-reactive to reactive conditions.