Vapor-Liquid Equilibria Azeotropic Data Activity Coefficients at Infinite Dilution Liquid-Liquid Equilibria Solid-Liquid Equilibria Gas Solubilities Henry Coefficients Critical Data Vapor-Liquid-Liquid Equilibria Solubilities of High Boiling Substances in Supercritical Fluids
To measure these properties different experimental devices are available to meet the requirements of different applications. By choosing one of the suggested properties you will get more information.
Distillation is still the most used separation process in the chemical and petrochemical industry. Simulation programs provide a larger variety of possibilities for process synthesis, design and optimization. However, the quality of the results obtained with these programs depends on the quality of the models and model parameters used. In some cases the results based on calculations using group contribution methods might be sufficient. In other cases the exact knowledge of the phase equilibrium of the involved components is indispensable. In these cases exact experimental data and a good description of them with the used thermodynamic models ought to be aspired.
The LTP GmbH (in cooperation with the University of Oldenburg) deploys several apparatuses to measure the VLE data. Each experimental setup has its special advantages, preferences, and its own range of applicability. In the following numeration the different methods are suggested and explained in detail.
Azeotropic informations are most important for the synthesis of distillation processes.
Activity Coefficients at Infinite Dilution
Activity coefficients at infinite dilution (g¥) are important for:the development of predictive methods (e.g. mod. UNIFAC (Do))
- characterizing the behavior of liquid mixtures
- fitting gE-model parameters (e.g. Margules, van Laar, Wilson, NRTL, UNIQUAC)
- predicting the existence of an azeotrope
- the estimation of mutual solubilities
- providing incisive information for the statistical thermodynamicist (no solute-solute interactions)
- analytical chromatographers
- screening solvents for extraction and extractive distillation processes
- the calculation of limiting separation factors necessary for the reliable design of distillation processes
- the calculation of Henry constants and partition coefficients
Several methods were developed for the measurement of
g¥. The most important methods are: gas-liquid chromatography (GLC), non-steady-state gas-liquid chromatography, differential ebulliometry, static methods and the dilutor method. Chromatographic methods allow the determination of g¥ of volatile solutes in high (classical GLC) and low boiling (non-steady-state GLC) solvents. The dilutor method permits the determination of g¥ in solvent mixtures. The addition of water to selective solvents (e.g. NMP + water) often increases the selectivity of the solvents used.
Gas-Liquid Chromatograph Dilutor
Analytical Method Liquid - Liquid Countercurrent Chromatography Static Apparatus, High Pressure
