Reactor Concept for Contactless Kinetic Measurement in Oscillating Droplets via Raman Spectroscopy

Klement, Torsten; Kockmann, Norbert; Röder, Thorsten

doi:10.1002/cite.201800199

Cited by 5 publications

(7 citation statements)

References 22 publications

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“…Similar to the widespread application of NIR spectroscopy for in situ monitoring of chemical reactions, particularly polymerisation reactions [23,24], Raman spectroscopy can be employed. Previous research by Klement et al has shown that the integral of the C=C stretching vibration band can be correlated linearly to the acrylic acid (AA) concentration in aqueous solutions from 20 g/L up to 400 g/L [25]. Because the Raman spectrum of isopropyl alcohol does not overlap with this band, the AA concentration could be measured throughout the whole polymerisation reaction.…”

Section: Inline Monitoring and Polymerisation Rate Determinationmentioning

confidence: 99%

Kinetic Study on Acrylic Acid Polymerisations in Isopropanol

Betz¹,

Westhues²,

Pauer³

2021

Applied Sciences

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The radical polymerisation of acrylic acid is largely concentration dependent and affected by the type of the surrounding solvent. This work investigates reaction rate constants, the activation energy, heat flux and the molecular weight in the industrially relevant synthesis of low molecular mass acrylic acid polymers in 2‑propanol. The polymerisations were carried out isothermally in an RC1e calorimeter with inline Raman spectroscopy for monomer concentration monitoring. For a non-neutralised acrylic acid in isopropanol (150 g/L), a monomer reaction order of 1.73 ± 0.15, an activation energy of 58.6 ± 0.8 kJ/mol (0.5 mol% AIBN) and 88.5 ± 1.5 kJ/mol (1.0 mol% AIBN), and a reaction enthalpy of 66.4 ± 4.8 kJ/mol could be shown. This data is in accordance with the literature values for acrylic acid polymerisation in water. In addition, linear correlations between the respective reaction parameters and the molecular weight for customised polymer synthesis in the range from 1.2 to 1.7 × 104 g/mol could be established. In comparison with aqueous acrylic acid polymerisation, it was found that the reaction rate constants in isopropanol were slower by a factor of approximately 10 under similar reaction conditions.

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Section: Inline Monitoring and Polymerisation Rate Determinationmentioning

confidence: 99%

Kinetic Study on Acrylic Acid Polymerisations in Isopropanol

Betz¹,

Westhues²,

Pauer³

2021

Applied Sciences

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“…It was further developed by the research group of Röder et al. for rapid and slow reactions . This method allows for independently choosing the residence time and screening the chemical process time scale.…”

Section: Droplet-based Reaction Screeningmentioning

confidence: 99%

“…21 It was further developed by the research group of Roder et al for rapid 44 and slow reactions. 45 This method allows for independently choosing the residence time and screening the chemical process time scale. It is necessary for the implementation of the oscillating flow to monitor the slug inside the CFI.…”

Section: Droplet-based Reaction Screeningmentioning

confidence: 99%

Two-Phase Flow in a Coiled Flow Inverter: Process Development from Batch to Continuous Flow

Bobers

Grühn

Höving

et al. 2020

Org. Process Res. Dev.

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The transfer of batch processes to continuous flow is a major driver for the application of microreactors. Here, we present a methodology for the transfer of (bio)chemical reactions in batch mode to two-phase continuous flow. For our purposes, the coiled flow inverter (CFI) is a promising reactor design providing enhanced heat and mass transfer, narrow residence time distribution, and rapid mixing. First, this methodology is used for current development of a droplet-based reaction screening system, which was first tested with a Paal−Knorr pyrrole synthesis as model reaction. The reaction was successfully performed in the automated screening system. The yields compared to the batch mode revealed enhanced mass transfer of the product into the continuous phase. Second, we investigated the biocatalyzed oxidation of ABTS by the enzyme laccase in a straight capillary for process development in a CFI. Because of its high flexibility regarding substrate specificity, laccase oxidizes many substrates with a colored product. Hence, an optical evaluation method for determination of reaction rate is used. We compare the Michaelis−Menten kinetic of the batch reaction and the continuous reaction in a capillary. The results show that the batch reaction can be mapped to the capillary setup. However, the capillary in continuous operation enables higher screening capacity of different reaction conditions and simple scale-up procedure.

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“…16 In order to overcome this challenge, a 3-phase microreactor, in which an oscillating droplet is passing a catalyst in a millimetre scaled capillary, was developed. Up to date, such oscillation setups were mainly applied to 2-phase systems [17][18][19][20][21] and in the context of the microfluidic synthesis of nanocrystals 22,23 starting from a solution-phase.…”

Section: Introductionmentioning

confidence: 99%