Session: 13-01: Carbon Capture & Cleaner Fossil Fuel Technologies

Paper Number: 138332

138332 - Optimizing Electrochemical Co2 Reduction to Formate Using Temperature Variations in Batch and Flow Reactors 

Abstract: 

Coupled with the move to renewable energy is a reduction in CO₂ emissions to fossil fuels. Existing CO₂ emissions can be mitigated through carbon capture and conversion to value-added fuel products – essentially, the inverse of combustion. Several different fuels can be produced from CO₂ depending on chemical reaction pathways taken, which can be guided by different material catalysts. One value product of interest is formic acid (FA), which has valuable applications in livestock feeds, fuel cells, and hydrogen storage.

 

As state-of-the-art processes to produce FA require high temperatures and pressures to operate, electrochemical processes are preferred in part due to their lower energy requirements. Moreover, electrochemical systems can be tuned to select certain products based on the catalyst used. CO₂ is typically converted to FA in the form of formate using either tin, lead, or bismuth-based metal catalysts. However, while ambient conditions do not require additional energy input, studies have shown that increasing temperature and pressure to conditions just above ambient can have favorable electrochemical conversion results. Studies on the combined effects of temperature and pressure have not been as studied in-depth simultaneously, but they may play an important role in future applications, such as using already-pressurized input CO₂ or accounting for temperature increases from solar for photoelectrocatalytic CO₂ conversion.

 

Here, we evaluate the performance of CO₂ conversion to formate by examining at a range of temperatures and pressures above ambient conditions, to determine how both conditions can be used to optimize formate production and corresponding efficiency. The electrochemical system consists of a tin-coated copper cathode in a carbonate electrolyte, against a platinum anode in an acidic electrolyte to serve as a proton source. As is typical in most studies, protons diffuse through a Nafion membrane to react with CO₂ in the cathode, resulting in the production of formate.

Our study is unique in that the effects of temperature and pressure will be evaluated in both a small-scale batch cell and a larger flow cell, where electrolytes can be sized differently. Different voltages are also tested to evaluate how temperature may affect the optimal voltage in the cathode. The design, evaluation of temperature variations, and testing of both cells will be described in this work. The results confirmed that temperature could enhance production of formate, but only at certain applied voltages below 1.8 vs. Ag/AgCl reference electrode. The combined effects of temperature with applied voltage will be useful for optimizing the performance in photoelectrocatlytic systems, where input energy can be partially or fully applied by solar. Presently, new design work is being done to develop and test a solar batch cell so that the real-world conditions integrating the temperature effects can be evaluated. The development and results from this initial iteration of the solar cell will be reported as well.

Presenting Author: Daniel Moreno Missouri State University

Presenting Author Biography: Dr. Daniel Moreno is an Assistant Professor of Mechanical Engineering at Missouri State University's Cooperative Engineering Program, with a joint appointment in the PAMS (Physics, Astronomy, Materials Science) department and a courtesy appointment at Missouri University of Science & Technology. He received his Bachelor’s degree in Mechanical Engineering at the Cooper Union for the Advancement of Science and Art in New York City. He received his Master’s and Ph.D. at Georgia Institute of Technology, also in Mechanical Engineering. Dr. Moreno’s teaching expertise is in the thermal sciences. His research integrates thermodynamics concepts in ME with the multi-disciplinary field of electrochemistry to promote renewable energy technologies. Projects that he has worked on consisted of applications in batteries, fuel cells, carbon capture, and capacitive technologies for water desalination. Presently, Dr. Moreno is interested in exploring innovative, reliable energy resources to foster a cleaner environment and eliminate harmful atmospheric emissions.

Authors:

Daniel Moreno Missouri State University
Joe Cota Missouri State University
Gavin Reese Missouri State University