An innovative way to reduce CO2: combination of ionic liquid and microtechnology

Significance 

Reduction of carbon dioxide emission is a global concern owing to its significant contribution to the greenhouse effect. Processes that contribute to the sequestration of carbon dioxide have thus been under development and research worldwide. The efficient reduction of carbon dioxide in ionic liquids has over time been proven to be a resourceful sequestration technique, since ionic liquids have relatively high solubility of CO2 allows more interactions with protons and electrons generating various chemical compounds that contain atomsone or multiple carbon atoms. From the wide variety of ionic liquids available for utilization in such a process, wet BMIM-BF4 (1-butyl-3-methylimidazolium tetrafluoroborate) has been adopted in this study owing to the fact that it can form complex hydrogen bonds that lower the activation energy required for CO2 reduction. Advantages of this technique can be viewed in the form of reduced carbon taxes for carbon dioxide emitting industries, or generation of fuels, such as methane and methanol, from renewable energy resources.

Dr. Yu Miao (currently a post-doctoral fellow at Baylor University), Professor Goran Jovanovic at Oregon State University, and Professor Alexandre Yokochi (currently at StateBaylor University) in collaboration with Nuchanart Siri-Nguan and Dr. Thana Sornchamni from PTT Public Company Limited in Thailand developed an electrochemical microscale-based reaction system that could convert CO2 into more valuable chemicals such as methane and methanol. Generally, they are working on the updevelopment and design of systems that could sequester carbon dioxide gas from various sources such as combustion exhausts, landfill biogas and emission gas from natural gas reforming processes. Their work is currently published in the research journal, Chemical Engineering Journal.

The team commenced their studies by designing and fabricating an electrochemical microscale-based reaction system (see Figure 1). Next, the developed system was utilized for the reduction of CO2 in the presence of wet ionic liquid BMIM-BF4 and studied under various experimental conditions controlled by factors such as micro-reactor height, solvent concentration and mean residence time of fluids in the micro-reactor. They then developed a mathematical model that reflected the geometry and flow conditions within the micro-reactor so as to simulate the chemical reaction process. Eventually, they determined the parameters of the mathematical model using an optimization process in which the best fit between the experimental data and the model prediction was achieved.

The authors observed that the ionic liquid solution used as the solvent increased the net consumption of CO2 and current efficiency. A comparison between the primary reaction rate constants in de-ionized water and wet BMIM-BF4 solution revealed that in both solvents, the reaction rate constants were almost in the same order of magnitude with slight differences on the value. Furthermore, an improved understanding of the reactor system was achieved by comparing predictions from numerical simulations with experimental observations.

The significance of Yu Miao and colleagues’ study is in incorporating of such micro-based technology at an industrial level can be highly rewarding in terms of reduced carbon taxes and future reuse of carbon captured following combustion to produce useful products.

 

An innovative way to reduce CO2: combination of ionic liquid and microtechnology. Advances in Engineering
Figure: Experimental Set-up of Microscale-based Electrochemical Reaction System for CO2 Reduction

 

About the author

Dr. Yu Miao is a chemical engineer interested in energy conversion, electrochemical and chemical reactions, and microscale technology. He began his academic career in China, graduating with a B.S. in Chemical Engineering from Shenyang University of Chemical Technology, working on the synthesis of chiral catalysts, funded by Ministry of Science and Technology of the Government of P. R. China. In 2010, he moved to Oregon to pursue his M.Sc. and Ph.D. degrees in chemical engineering at Oregon State University. He was working on the CO2 reduction projects funded by PTT Public Company Limited in Thailand. After earning his Ph.D., he conducted postdoctoral work at Oregon State University and Baylor University, researching on the conversion of natural gas using corona discharge funded by ARPA-E, a U.S. government agency under U.S. Department of Energy. Dr. Yu Miao is now a postdoctoral research associate in ECS at Baylor University.

About the author

Mrs. Nuchanart Siri-Nguan is a chemical engineer at PTT Public Company Limited in Thailand. She obtained her M.Sc. degree from Chulalongkorn University.

About the author

Dr. Thana Sornchamni is a chemical engineer at PTT Public Company Limited in Thailand. He obtained his M.Sc. and Ph.D. degrees from Oregon State University. His current research focuses on Microchannel-based Gas to Liquids Technology (GTL) for flared gas and small to medium-stranded gas reserves.

About the author

Dr. Goran N. Jovanovic is a professor in chemical engineering at Oregon State University. His current research focuses in two microscale technology areas: development of microscale chemical reactors and separators suitable for the development of microscale based chemical processes (NSF), and the development of microscale biosensors devices (DARPA). Dr. Jovanovic is, also, leading research projects in the development of “Zero gravity-compatible chemical processes for long space missions” (NASA) and “Environmental microreactors for in situ deployment” (INEEL).

About the author

Alex Yokochi is a Professor of Mechanical Engineering at Baylor University. He received a B.S. and M.S. from Southern Illinois University at Carbondale and the Ph.D. from Texas A&M University, all in chemistry.

His research and teaching interests focus on process and reaction engineering and the development of novel materials applied to the areas of energy sustainability, including energy conversion and storage, or the development of functional materials with advanced properties through the development of nanocomposites. His work is supported by state and federal agencies including the US-DoE/ARPA-E and the US-NSF including a CAREER award, and industrial partners like PTT.

Reference

Yu Miao, Nuchanart Siri-Nguan, Thana Sornchamni, Goran N. Jovanovic, Alexandre F. Yokochi. CO2 reduction in wet ionic liquid solution in microscale-based electrochemical reactor. Chemical Engineering Journal, volume 333 (2018) pages 300–309

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