Modellbasierte Entwicklung eines kontinuierlichen Reaktors zur Herstellung und in-situ Abtrennung von 5-Hydroxymethylfurfural

  • Model-based equimpent design of a continuous reactor for production and in-situ separation of 5-hydroxymethylfurfural

Aigner, Maximilian; Jupke, Andreas (Thesis advisor); Klankermayer, Jürgen (Thesis advisor)

Aachen : RWTH Aachen University (2021)
Dissertation / PhD Thesis

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2021

Abstract

Herein, the production of 5-hydroxymethylfurural (5-HMF) from fructose in in a liquid-liquidtubular reactor is proposed. In this intensified reactor in-situ extraction of 5-HMF into a disperse phase consisting of the solvent 2- methyltetrahydrofuran (2-MTHF) is performed. The disperse phase is contacted in a countercurrent flow relative to the continuous phase in which 5-HMF is produced. The design of this novel reactor concept follows a model-based approach. Based on a newly parameterized equation of state, the phase equilibrium of the ternary system 2-MTHF/water/5-HMF as a function of composition and temperature is described. Root mean square deviations for the thermodynamic model compared to experimental data are below 0.02 mol mol−1. From this accurate description of phase equilibria, the transport variables density and viscosity are calculated for both liquid phases within the range of experimental error. The acid-catalyzed dehydration of FRC to 5-HMF is described by a newly developed kinetic model. This kinetic model enables calculation of the temporal change in concentration caused by reaction and mass transport into the organic phase. Sedimentation and mass transport into the disperse phase are investigated in single-drop experiments. Based on these experimental data, parameters for the mathematical description of sedimentation and mass transfer are obtained. The results of the models developed in this work allow a calculation of sedimentation velocities with an accuracy greater than 0.015mms−1. Single-drop mass transfer calculations exceed an overall accuracy of 4%. The herein developed rate model for the description of local and temporal concentration profiles in the liquid-liquid tubular reactor allows a quick evaluation of the potential of this design. Due to the efficient extraction in the countercurrent mode of operation, the 5-HMF yield compared to batch results is increased by 16% at full conversion. Additionally, a validation experiment was carried out in a custom-made pilot plant. A comparison of experimental results and results of the reactor modeling for this validation experiment yields an accuracy greater than 80 %. An extrapolation of the model data to the stationary point of operation shows thata 5-HMF selectivity of 93% at 30% fructose conversion is achieved. The performance of the two-phase 5-HMF synthesis in the liquid-liquid tubular reactor developed in this work thus offers clear advantages compared to operation in a batch reactor.

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