(6a) Control and Automation of Fluid Flow, Mass Transfer and Chemical Reactions in Microscale Segmented Flow

Authors: 
Abolhasani, M., Massachusetts Institute of Technology

Owing to the constant increase of the worldwide energy demand due to the growth of populations and development of countries, the emissions of greenhouse gases (mostly carbon dioxide (CO2)) from fossil fuels will constantly increase. Currently, carbon capture and sequestration is one of the most efficient solutions to control and reduce the concentration of the released greenhouse gases in the atmosphere. However, the underground storage of the captured CO2 is expensive and limited to some specific locations. On the other hand, the current rate of energy consumption along with the inevitable global warming makes energy as one of the crucial worldwide issues of the near future. Therefore, there will be a huge demand for new sets of sustainable energy substitutes. In 2008, it was found that CO2 in the presence of a frustrated Lewis pair (FLP) and hydrogen can be quickly converted to methanol and water. It has been proposed that CO2 fuel conversion using the captured CO2 from power plants (or atmosphere) has the potential to be one of the key solutions to address the energy demand and global warming problems. However, measurement and characterization of the kinetics of CO2 conversion reactions (i.e., to methanol, ethanol or CO) in the presence of metal-free catalysts (FLPs) are currently challenging or in some cases impossible, owing to the mass transfer and time-resolution limitation of the conventional batch scale characterization tools.

During the past decade, microfluidic (MF)-based technologies have shown promising solutions as a high throughput characterization tool for investigation, screening, and optimization of gas-liquid reactions.

In my PhD, I was working on a multidisciplinary project, collaborating between Mechanical Engineering and Chemistry Departments of University of Toronto. During this time I have made significant contributions in flow chemistry and microfluidic (MF) research fields specifically related to screening gas solubilities in liquids, measuring thermodynamic characteristics of gas-liquid reactions associated with CO2 sequestration, characterizing CO2-governed liquid-liquid phase separation process (switchable water) and on-demand preparation of high quality colloidal nanomaterials (e.g. CdSe/CdS).

During this time, I designed and developed the first automated MF platform that allowed the routine screening of solubility data for a wide range of CO2-physical solvent mixtures. The platform allowed screening of approximately 300 different conditions (temperature and pressure) during one day. In the next step, the developed automated MF strategy was utilized to measure, for the first time, thermodynamic characteristics of CO2-FLP reaction. I have also designed a two-phase MF platform for high temperature (240-330 ͦ C) synthesis of high quality (Fwhm ~30 nm) nanocrystals such as CdSe, CdS and ZnS. The silicon-based microreactor could produce high quality core or core/shell nanocrystals with desired spectral characteristics at a throughput of 0.6 ml/min.

As an independent scientist, I will focus on the development and utilization of MF platforms for the carbon capture in the presence of nanoparticles along with fuel conversion process. I will also study the underlying transport mechanisms in the presence of chemical reactions with experimental and numerical methods.