Numerical and Experimental Quantification of the Performance of Microreactors for Scaling-up Fast Chemical Reactions

Convergent approach for direct cross-coupling enabled by flash irreversible generation of cationic and anionic species

In biosynthesis multiple kinds of reactive intermediates are generated, transported, and reacted across different parts of organisms, enabling highly sophisticated synthetic reactions. Herein we report a convergent synthetic approach, which utilizes dual intermediates of cationic and carbanionic species in a single step, hinted at by the ideal reaction conditions. By reactions of unsaturated precursors, such as enamines, with a superacid in a flow microreactor, cationic species, such as iminium ions, are generated rapidly and irreversibly, and before decomposition, they are transported to react with rapidly and independently generated carbanions, enabling direct C-C bond formation. Taking advantage of the reactivity of these double reactive intermediates, the reaction take place within a few seconds, enabling synthetic reactions which are not applicable in conventional reactions.

LED-irradiated photo-Fenton process on pollutant removal: outcomes, trends, and limitations

This manuscript critically reviews the state of the art on the application of photo-Fenton processes irradiated by light-emitting diode arrays (LED) with a focus on the removal of contaminants of emerging concern (CEC) from aqueous matrices. LEDs are clean, low-cost radiation sources with longer lifespan compared to mercury lamps. This study covers the influence of LED sources, wavelengths, and dose upon CEC removal, and the potential for disinfection, abatement of antibiotic-resistant bacteria (ARB), and genes (ARG). The bibliographic search was performed in Scopus database using keyword combinations and resulted in a portfolio containing 52 relevant articles published between 2010-2023. According to reviewed papers, LED photoreactor design has evolved in the past decade aiming to improve CEC degradation in aqueous matrices while reducing construction and operation costs, and energy consumption. Among several reactors (annular, fluidized bed, parallel plate, wireless, pathway systems, and microreactor) surveyed for their performance and scalability, LED chips and strips are particularly suitable for application due to their wide emission angle (≈120°) and small size (mm2), which allow for, respectively, efficient illumination coverage and flexible arrangement and design. LED microreactors are very efficient in the degradation of contaminants and scalable with reduced area requirements. Although most studies were performed in synthetic solutions and at laboratory scale, the externally LED irradiated cylindrical reactor was successful for application in full-scale municipal water treatment plants. Future studies should focus on evaluating CEC removal in wastewater using scalable devices for continuous operation of solar photo-Fenton at night.

Process Intensification of a Napabucasin Manufacturing Method Utilizing Microflow Chemistry

Microflow chemistry is one of the newest and most efficient technologies used today for the safe and effective production of medicines. In this paper, we show the use of this technology in the development of a manufacturing method for napabucasin, which has potential in the treatment of colorectal and pancreatic cancers. In conventional "batch-type" reactor systems, the generation of side products can be controlled with traditional techniques such as reagent reverse-addition and temperature control. However, there is a limitation to which the yield and purity can be improved by these methods, as both are constrained by the efficiency of heat/mass transfer. Applying microflow chemistry technology alters the parameters of the constraint through the use of precise mixing in a microchannel, which offers increased possibility for improving yields and process intensification of the napabucasin process. Reported herein is a proof-of-concept study for the scale-up production of napabucasin using microflow chemistry techniques for manufacturing at the kilogram scale.

Reactor performance estimation in microscale flow calorimeter for rapid characterization of exothermic reactions

Abstract

Continuous flow calorimeters are a promising tool in process development and safety engineering, especially for flow chemistry applications to characterize the heat release and kinetic parameters of rapid chemical reactions. In this study, the digital accompaniment of an isoperibolic flow calorimeter for characterization of exothermic reactions is presented. To support experimental planning and evaluation, computational fluid dynamic simulations are carried out for single-phase flow in the microreactor. The residence time distribution is obtained and used for estimation of conversion and temperature profiles along the microreactor channel. This leads to an integration of CFD simulations into the calorimeter’s software-guided workflow reducing the experimental effort regarding the determination of thermokinetic data. The approach is tested for a highly exothermic test reaction, which provides further hints for future investigations.

Article highlights

• Estimation of conversion and temperature profiles within a microscale calorimeter

• Combination of CFD simulations and reactor performance estimation

• Approach was tested for highly oxidation of sodium thiosulfate

• Estimated conversion and temperature profiles are in good agreement with experimental data

Graphical abstract

Kinetic Modeling of an Enzyme Membrane Reactor for the Selective Production of Oligosaccharides

An enzyme membrane reactor is an attractive tool for producing oligosaccharides from biomass-based polysaccharides. However, kinetic modeling and reactor design based on the rate equations have rarely been reported for enzyme membrane reactors because of the difficulty in tracing the depolymerization process. In this study, a simplified reaction model based on Michaelis–Menten-type kinetics has been built to simulate the enzyme membrane reactor. Ramping various species into reactant, target, and byproduct worked well for discussing reactor performance. The use of a membrane with a molecular weight cut-off (MWCO) of 10 kDa with continuous feeding of the reactant was suggested for the efficient production of chitosan hexamer and pentamer by enzymatic hydrolysis of chitosan.

Software-guided microscale flow calorimeter for efficient acquisition of thermokinetic data

Fast chemical process development is inevitably linked to an optimized determination of thermokinetic data of chemical reactions. A miniaturized flow calorimeter enables increased sensitivity when examining small amounts of reactants in a short time compared to traditional batch equipment. Therefore, a methodology to determine optimal reaction conditions for calorimetric measurement experiments was developed and is presented in this contribution. Within the methodology, short-cut calculations are supplemented by computational fluid dynamics (CFD) simulations for a better representation of the hydrodynamics within the microreactor. This approach leads to the effective design of experiments. Unfavourable experimental conditions for kinetics experiments are determined in advance and therefore, need not to be considered during design of experiments. The methodology is tested for an instantaneous acid-base reaction. Good agreement of simulations was obtained with experimental data. Thus, the prediction of the hydrodynamics is enabled and the first steps towards a digital twin of the calorimeter are performed. The flow rates proposed by the methodology are tested for the determination of reaction enthalpy and showed that reasonable experimental settings resulted.

Graphical abstract

A methodology is suggested to evaluate optimal reaction conditions for efficientacquisition of kinetic data. The experimental design space is limited by thestepwise determination of important time scales based on specified input data.