Integration of modern computational chemistry and ASPEN PLUS for chemical process design

Abstract

Thermodynamic properties and fluid phase equilibria are crucial for the design and development of a chemical process. However, such data may not always be available, particularly for fine or specialty chemicals. In this work, we evaluate the reliability of using modern computational chemistry combined with recently developed predictive thermodynamic models to provide all the thermodynamic properties required in process design with ASPEN PLUS. Specifically, the G3 method is used for the ideal gas heat capacities and properties of formation, and the PR+COSMOSAC equation of state and COSMO‐SAC activity coefficient model are utilized for the properties and phase behaviors of pure and mixture fluids. These methods are chosen because they do not require any species‐dependent parameters and can, in principle, be applied to any chemical species. For a set of 972 chemicals, it is found that most properties can be predicted with a satisfactory accuracy (less than 10%: critical temperature [5%], critical pressure [10%], critical volume [5%], constant pressure ideal gas heat capacity [5%], and heat of vaporization [10%], except for the acentric factor [33%] and vapor pressure [73%]). Furthermore, the predicted results show little bias suggesting that these theoretically based methods are reliable for new chemicals for which experimental data are not yet available. Our analyses show that better accuracy in the prediction of vapor pressure and formation enthalpy and free energy is necessary for the design of chemical processes without relying on any experimental input. Nonetheless, these methods often provide reliable relative property values (e.g., relative value of normal boiling temperature can be predicted with 94% accuracy), making it possible to screen for new chemicals for improving existing processes.

Fast Correction of Errors in the DFT‐Calculated Energies of Gaseous Nitrogen‐Containing Species

“…The heat of formation is among the most important thermodynamic properties of compounds. It can be used to calculate reaction enthalpies and free energies (when suitably combined with entropy values), which are paramount in a wide variety of applications in chemistry and chemical engineering such as energy storage, [1,2] chemical reaction engineering, [3][4][5] process system design, [6] combustion, [7] electrocatalysis, [8][9][10] and thermochemical and electrochemical stability assessment. [10][11][12][13][14][15][16] However, experimental heats of formation are unavailable for a vast number of compounds.…”

Condensable Gases Capture with Ionic Liquids

“…55 Furthermore, the COSMO-SAC model has already been embedded into the latest version of Aspen Plus software because its program codes are open access (https://www.design.che.vt.edu). 56 2.2.1.1. COSMO-RS Model.…”

“…Thus, in 2018 we proposed the COSMO-RS model, especially for ILs which was embedded into the Amsterdam Modeling Suite software as a separate module named after “ADF Lei 2018” to improve the predictive accuracy for the containing-ILs systems . Furthermore, the COSMO-SAC model has already been embedded into the latest version of Aspen Plus software because its program codes are open access () …”

Thermodynamic Analysis of CO2 Hydrogenation to Ethanol: Solvent Effects

“…The effects of solvents on CO 2 hydrogenation reaction have been widely investigated; however, the thermodynamic influence of solvent in condensed state on CO 2 hydrogenation to ethanol under various temperatures and pressures have not yet been well studied. Since calculating the properties of condensed fluid by ab initio methods require a high demand for computational resources, [23] in this work, we used Aspen Plus, which predicts the properties of condensed fluid using engineering thermodynamic models to illustrate the effects of solvents on the thermodynamics of ethanol synthesis by CO 2 hydrogenation under various temperatures and pressure. We found that the dielectric constant and the saturated vapor pressure of the solvent are of critical importance for ethanol synthesis by CO 2 hydrogenation.…”