Measuring Kinetics in Flow Using Isoperibolic Flow Calorimetry

Abstract

Continuous flow calorimeters are a promising tool in process development and safety engineering, particularly for flow chemistry applications. An isoperibolic flow calorimeter is presented for the characterization of exothermic reactions. The calorimeter is adapted to commercially available plate microreactors made of glass and uses Seebeck elements to quantify the heat of reaction. For automation of calibration procedures and calorimetric measurements, the device is connected to a lab automation system. Reaction enthalpy of exothermic reactions is determined via an energy balance of the entire calorimeter. Characterization of reaction kinetics is carried out via a local balancing of the individual Seebeck elements without changing the experimental setup, while using the previous measurements and additional ones at higher flow rates. The calorimeter and the associated measurement procedures were tested with the oxidation of sodium thiosulfate using hydrogen peroxide. Reaction enthalpy was determined to be 594.3 ± 0.7 kJ mol−1, which is within the range of literature values.

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

“…Khaydarov et al [22] also investigated the LTF-MS reactor regarding its mixing performance using CFD and experiments for validation. Additionally, the reactor is currently employed in the microcalorimeter enabling a validation with experimental data [26]. The reactor consists of two straight inlet channels, which merge in a Y-mixer, followed by a chicane mixing geometry with eleven identical mixing elements.…”

“…With the exception of the mixing geometry, the compartments are chosen to match the areas of the heat flux sensors used in our experimental setup [26]. Thus, experimentally determined heat transfer coefficient can be used for those reactor parts.…”

“…Prior to the experiments, the SEs have been calibrated and baseline signal of the SEs have been recorded. Further and more detailed information can be found in [26] on the experimental procedure and the calorimetric measurement method itself.…”

“…Thus, the largest possible design space is predicted. The same experimental parameters were chosen as in the experiments performed by Frede et al [26], in order to further compare the prediction with experimental data. The inlet and ambient temperatures were set to 25 °C and concentrations of c NaTS = 1.0 M and c HP = 2.2 M were used.…”

“…The focus here is put on the simplification and acceleration of estimation of temperature and conversion profiles of fast and exothermic reactions within microreactors. The coupling of CFD and reactor performance estimation is shown for the oxidation of sodium thiosulfate (NaTS) using hydrogen peroxide (HP) as a test reaction and compared to experimental data determined in our microcalorimeter [26]. This leads to an integration of CFD simulations into a microcalorimeter's software-guided workflow reducing the experimental effort regarding the determination of thermokinetic data.…”