Dr. Economou is a Professor of Chemical Engineering at Texas A&M University at Qatar. From 2009 to 2012, he was the Associate Provost for Graduate Studies in the Petroleum Institute, Abu Dhabi and prior to that the Director of the Molecular Thermodynamics and Modeling of Materials Laboratory of the National Center for Scientific Research “Demokritos” in Athens, Greece. He worked as a visiting scholar in several institutions around the globe (Delft University, Exxon Research and Engineering Company, University College London, Princeton University, the Technical University of Denmark and the American College of Greece). He has consulted for major oil and chemical companies worldwide. He published 125 peer-reviewed research papers in leading journals in areas related to molecular thermodynamics and molecular simulation of complex fluids for chemical process and product design. He has served in many national and international research and policy committees.
Development and Validation of Molecular-Based Models for the Prediction of Thermodynamic and Transport Properties of CO2 – Brine Mixtures
Funded by Qatar National Research Fund (NPRP 6-1157-2-471)
We aim to develop fundamental understanding of molecular interactions in CO2 – brine mixtures of importance to Carbon Capture and Sequestration (CCS) processes through molecular simulations (Molecular Dynamics and Gibbs Ensemble Monte Carlo methods) and equation of state models. Sub-tasks include:
(a) Evaluation of the accuracy of current molecular models over a broad range of temperatures, pressures and salt concentration relevant to CCS processes with respect to phase behavior and transport properties of CO2 – H2O – NaCl mixture,
(b) Development of efficient computational methods and improved potential models for these properties,
(c) Assessment of the accuracy of SAFT/PC-SAFT based models for the phase behavior of CO2 – H2O – NaCl mixture and improvement of the model(s) using data generated through molecular simulations,
(d) Development of appropriate engineering models for the correlation of viscosity and self-diffusion coefficient experimental and molecular simulation data for the CO2 – H2O – NaCl mixture, and
(e) Identification and remediation of inconsistencies and gaps in available experimental data.
Collaborating partner: Professor Athanassios Z. Panagiotopoulos, Department of Chemical Engineering, Princeton University, New Jersey, USA.
Gas Storage and Transportation, and Separation Process Development Based on Hydrates
Funded by Qatar National Research Fund (NPRP 6-1547-2-632)
Gas hydrates are ice-like, crystalline materials that belong to the class of clathrates (i.e., inclusion compounds). They are composed of a framework of hydrogen-bonded water molecules that form cavities with specific geometry and size, inside which small guest molecules can be enclathrated. The stability of hydrates is due to the intermolecular interactions between the lattice of water molecules and the trapped gas. However, in the absence of the guest gas, they are not stable. Different types of hydrates exist based on their crystal structure, such as structures sI, sII, and sH. The primary interest in clathrate hydrates arises from their capacity to store large volumes of gas. Consequently, they have been considered as an alternative material for storing and/or transporting “energy-carrier” gases like CH4 and H2.
The focus of the current project is on the development of fundamental knowledge related to the use of hydrates for:
(a) Gas (such as CH4 and CO2) separation, storage and transportation, and
(b) Separation processes, including gas/gas separation.
For these purposes, our work focuses on:
(a) Experimental measurements to determine stability curves of various hydrate forming systems, with and without inhibitors/promoters,
(b) Molecular simulations to determine hydrate phase equilibria, hydrate kinetics and hydrate cage occupancies, and
(c) Development and validation of macroscopic thermodynamic models for the prediction of phase stability of multicomponent mixtures.
Collaborating partner: Dr. Athanassios K. Stubos, Environment Research Laboratory, National Center for Scientific Research “Demokritos,” Athens, Greece.
Molecular Simulation of Diffusion and Solubility of Hydrogen, Carbon Monoxide and Water in Heavy n-Alkanes
Funded by Shell Global Solutions
The Gas-To-Liquid (GTL) process is a technologically and financially attractive process for the production of high value hydrocarbons from natural gas. It is based on Fischer-Tropsch synthesis that involves conversion of a mixture of H2 and CO into liquid hydrocarbons. For the efficient design, simulation and optimization of the industrial process, accurate knowledge of solubility and diffusivity of various gases in the heavy hydrocarbons is needed. A combination of molecular simulation using state-of-the art molecular models with sophisticated experimental measurements using Dynamic Light Scattering (DSL) has been adopted in this project.
Our contribution refers to:
(a) Development of a molecular force-field for heavy n-alkanes from n-C8 to n-C100 and for the three solutes H2, CO and H2O,
(b) Validation of the force-field against literature data for diffusivity of the gases in light n-alkanes,
(c) Prediction of the diffusivity of gases in n-alkanes for high n values and in mixtures of n-alkanes at elevated temperature conditions,
(d) Calculation of Maxwell–Stefan and Fick diffusion coefficients and comparison with experimental data provided from the University of Erlangen-Nüremberg,
(e) Viscosity calculations in pure n-alkanes and in mixtures of them at a wide temperature range and comparison with experiment measurement,
(f) Development of empirical correlations for the properties of interest to be used in process simulation, and
(g) Solubility calculations using molecular simulation (Widom particle insertion) and equation of state models (SAFT/PC-SAFT).
(a) Dr. Matthieu Fleys, Shell Global Solutions, Amsterdam, The Netherlands,
(b) Professor Andreas P. Fröba, Department of Chemical and Biological Engineering, University of Erlangen-Nüremberg, Germany.
Design of Novel Materials Based on Ionic Liquids for CO2 Capture from Power Plants and for Efficient Gas Separation Processes
Funded by the European Commission
Ionic Liquids (ILs) have evolved in recent years as promising environment friendly materials for a number of applications in chemical process industries. In this project, novel ILs are investigated as suitable materials to be used in membranes for CO2 capture and separation of CO2 – containing gas mixtures. The major tasks of the project are synthesis and characterization of new ILs, experimental measurements and theoretical modeling of physical properties of the ILs and gas mixtures therein, and pilot plant testing of the new membranes.
Our contribution consists of:
(a) Development of atomistic models for various families of imidazolium-based ILs. In particular, [Tf2N–] and [TCM–] ILs are examined,
(b) Calculation of molecular structure and physical properties of these ILs and systematic investigation of the effect of chemical structure on the properties of interest,
(c) Prediction of solubility and diffusivity of CO2 and other industrial gases in these ILs and calculation of the gas separation efficiency of the various ILs,
(d) Comparison of model predictions against experimental data and independent assessment of the quality of experimental data from different sources.
(a) Professor Andreas P. Fröba, Department of Chemical and Biological Engineering, University of Erlangen-Nüremberg, Germany
(b) Dr. Xenophon Krokidis, Scienomics SARL, Paris, France.
Molecular Thermodynamics and Simulation Laboratory
MTSL research is exclusively theoretical/computational. We are the largest user of the TAMUQ high-performance computing facilities that consist of 2,208 CPU cores with an aggregate system memory of 9,000 GB and a peak performance of 42+ Tflops.