Abstract
Three-dimensional (3D) Fe/SiC monoliths with parallel interconnected channels and different cell geometries (square, troncoconical, and triangular) were manufactured by robocasting and used as catalytic reactors in hydroxylation of phenol using hydrogen peroxide to produce dihydroxybenzenes; the reaction was performed at Cphenol,0 = 0.33 M, Cphenol,0:CH2O2,0 = 1:1 M, WR = 3.7 g, T = 80–90 °C, and τ = 0–254 gcat·h·L–1 with water as a solvent. The values of the apparent kinetic rate constants demonstrated the superior performance of the triangular cell monoliths for hydrogen peroxide decomposition, phenol hydroxylation, and dihydroxybenzene production reactions. A computational fluid dynamic model was validated with the experimental results. It demonstrated that the triangular cell monoliths, with a lower channel hydraulic diameter and not-facing interconnections, provided a higher internal macrotortuosity that induced an oscillating flow of the liquid phase inside the channels, leading to an additional transverse flow between adjacent parallel channels. This behavior, not observed in the other two geometries, resulted in a better overall performance.
Highlights
One of the key factors that determine the reactor performance is the geometry of the reactor.[1−3] It is designed to provide maximum conversion and selectivity at minimum catalyst load and operating cost
For the fluid dynamic study, three consecutive 3D channels were built to study the transverse flow by the interconnections, while for the modeling study, only one 3D channel was considered for simplification
The TRG geometry accounts for a higher macrochannel tortuosity that causes a deviation of the fluid in the channel
Summary
One of the key factors that determine the reactor performance is the geometry of the reactor.[1−3] It is designed to provide maximum conversion and selectivity at minimum catalyst load and operating cost For this aim, the reactor must be adapted to achieve the best matching of fluid dynamics, heat transmission, and mass transport with the reaction kinetics. Hajimirzaee et al.[30] prepared 3D cordierite monoliths where the geometry of the cells was modified by selecting different rotation angles between adjacent layers These architectures with immobilized Pd/Pt were used as catalytic converters and tested in the oxidation of methane. Based on our recent works,27,32 3D Fe/SiC honeycomb monoliths with interconnected channels were additive manufactured by robocasting with different inner morphologies and applied to a demanding liquid-phase reaction, the selective oxidation of hydrocarbons. The results of this work will illustrate the full potential of coupling the 3D printing technology and numerical methods for the chemical reactor design
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