A new approach for a combined evaluation of calorimetric and online infrared data to identify kinetic and thermodynamic parameters of a chemical reaction

In order to identify parameters of a chemical reaction, such as rate constants, reaction orders, activation energies, or reaction enthalpies, we developed a new combined evaluation algorithm. In contrast to common evaluation procedures, it allows a simultaneous evaluation of online measured infrared and calorimetric data. Furthermore, a new weighting principle was developed that performs an automatic scaling of the infrared and calorimetric data in order to equalize their influence on the estimated reaction parameters. Such a scaling is of particular importance as two completely different measurement data sets are combined into one single objective function. The approach could be extended to more than two different analytical signals. The evaluation of the infrared data neither requires calibration nor knowledge of pure component spectra. Overlapping absorption bands are allowed. In addition, no calibration is needed for the calorimetric measurements. The feasibility of the new evaluation algorithm will be demonstrated based on the hydrolysis of acetic anhydride.