Measurement of CO/CO2 recombination rates for use in CO2 conversion applications – CO2REC

We use a plasma torch to produce a high temperature (7000 K) CO2/Ar mixture. This mixture exists in the form of a jet which exits the nozzle of the plasma torch. At this temperature, the dominant species present in the jet are Ar, CO, C and O. Electrons and ions are present as well in lesser quantities. The jet velocity is very high and we achieve rapid recombination by passing the high speed jet through a water-cooled tube. The walls of this tube, which are in contact with the plasma on one side, are cooled by water on the other and their temperature is maintained at 300 K. We vary the length of the water-cooled tube to increase or decrease the transit time and achieve more or less cooling. We propose to study the cooling of the high temperature jet, including the chemical recombination of species present, using a combination of optical emission spectroscopy and laser-based diagnostics such as laser-induced fluorescence. These diagnostics enable us to track the chemical species present and the temperature of the jet as it recombines and cools. The resulting data can then be compared with predictions made by chemical kinetic models.

in progress

in progress

Grimaldi, C., McGuire, S. and Laux, C. “Temperature and radiation measurements of an atmospheric pressure CO2 plasma”, 2020 AIAA Scitech Meeting, (AIAA 2020-1708).

Plasma reprocessing of CO2 is a technique used to convert CO2 to CO. The CO produced may then be used to create a fuel known as syngas. This process has the potential for turning CO2 into value-added products, and it has been proposed as part of several carbon-neutral energy systems. However, successful implementation of this reprocessing technique requires that it be done in an energy efficient manner. This, in turn, requires a detailed understanding of CO2 chemical kinetics: in particular, state-specific recombination kinetics. We propose using our plasma torch facility at CNRS laboratory EM2C to study relevant CO/CO2 recombination kinetics. Our facility can produce an equilibrium CO2 plasma with a temperature between 7000 and 9000 K. This plasma is then passed through a water-cooled tube which forces rapid recombination. We have successfully used this approach to study recombination kinetics in nitrogen plasmas. The relevant recombination dynamics are studied using optical diagnostics and the measurements are compared to models in order to extract state-specific recombination rates. We propose here measurements of species concentrations and temperature in a recombining CO2 plasma. This will be done using both optical emission spectroscopy and laser-based techniques (LIF). The state-specific data provided will be valuable for model validation and contribute to an understanding of the kinetic mechanisms behind plasma reprocessing of CO2.