Abstract
Calorimetric data from chemical reactions such as reaction enthalpy, adiabatic temperature rise, and activation energy are essential for reaction safety and scale-up from laboratory investigations to reactor design and operation. Typically, these data are gained from batch calorimeters with sophisticated setups and elaborate measurement procedures. Continuous flow calorimeters, compared with batch setups, have different mixing and heat transfer characteristics and enable harsh reaction conditions, particularly within microstructured reactors with their enhanced heat transfer capability. This review provides an overview of currently investigated and applied flow calorimeters in research and development in relation to existing concepts. Novel approaches for heat flux measurements as well as integrated sensors are presented. Safety aspects of flow chemistry are a main driver, but additionally, low material consumption is important in early process development. Limitations of the concepts are presented with a comprehensive literature overview of flow calorimetry to show that continuous flow calorimeters form a new tool in process development and safety engineering, particularly with microstructured devices and novel sensing techniques.
Highlights
The development of new chemical products and their transfer to production require a fundamental understanding of reaction mechanisms as well as kinetics, manufacturing processes, and associated process parameters.[1]
Reaction calorimetry enables quantification of the heat released in chemical reactions or physical processes and provides necessary basic safety information during chemical process and product development for fast reactions, which can be further developed into information regarding risk, scalability, and criticality of a process.[2]
This review aims to provide a perspective on current reaction calorimetry applications
Summary
The development of new chemical products and their transfer to production require a fundamental understanding of reaction mechanisms as well as kinetics, manufacturing processes, and associated process parameters.[1]. In further works,[43,44] a similar setup was developed to investigate a droplet-based system, some changes were made within the setup, including brass instead of aluminum for the temperature control plate, PTFE instead of PFA for the tubing, and a different IR camera (SC7000, FLIR) With this setup, mixing and enthalpy characterization of an acid−base reaction in droplet flow was performed. The approach of the residence ramp method for kinetic data collection was developed by Moore and Jensen.[55] an inline FTIR spectrometer (ReactIR, Mettler Toledo) was used to measure the concentration at the reactor outlet By this method, the reaction rate constant was determined at different temperatures in good agreement with the literature. Increased measurement performance was seen at total volumetric flow rates above 2 mL min−1, which was attributed to higher temperature losses at lower flow rates at the temperature measurements of both inlets
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