Tuning of Conversion and Optical Emission by Electron Temperature in Inductively Coupled CO₂ Plasma

Abstract

This paper focuses on how the electron temperature and other plasma properties affect optical emission and CO2 conversion in a CO2 plasma. Such plasma-mediated reactions can enable efficient CO2 reuse. We study CO2 and CO plasmas generated by inductively-coupled radiofrequency power (30-300 W) at low pressures (6-400 Pa). By varying the argon admixture, we can study the effect of the electron temperature, Te, on the conversion and emission properties using optical emission spectroscopy, mass spectrometry and electrical probe measurements. Importantly, we can observe several parameters simultaneously: Te, CO2 conversion, chemiluminescence from CO2 and dissociation products and optical emission from several atomic and CO transitions and from the C2 Swan system. Based on these results, we establish a correlation between Te, the CO2 conversion and the optical emission spectra. A low Te enhances CO2 conversion and Swan band emission. In contrast with published studies, our results show that the CO2 and C2 vibrations are not in local equilibrium. This means that the vibrational temperatures of CO2 and C2 should differ.

Boudouard reaction driven by thermal plasma for efficient CO2 conversion and energy storage

“…Since the OES window was positioned at the bottom of the added drift section below the plasma generator and very close to the carbon bed, these emission spectra indicate http://engine.scichina.com/doi/10.1016/j.jechem.2019.10.007 that, at least a significant fraction of the input CO 2 is decomposed into carbon monoxide, oxygen atoms or oxygen molecules by the plasma arc, and these components are incident on the carbon bed. The presence of the C 2 Swan band emission we interpret as evidence for a very low electron temperature [30] . This is very consistent with the fact that we are dealing with a thermal plasma.…”

Conversion of CO2 by non- thermal inductively-coupled plasma catalysis

“…RF-ICP driven CO2 splitting enables CO2 dissociation through vibrational activation (i.e. "selective excitation") of one degree of freedom [40]. The vibrationally excited CO2 will further interact with each other or collide with the plasma electrons, leading to a successive "vibrational pumping" up along the vibrational levels.…”

“…From earlier research (i.e. [40]) was learned that lower the pressure in a RF-ICP reactor can be beneficial to further increase the CO yield during CO2 splitting . FIG 3a shows that the presence of a metal mesh under higher pumping speed in the RF-ICP has a significant effect on the conversion of CO2.…”

A Critical Look at Direct Catalytic Hydrogenation of Carbon Dioxide to Olefins

“…[4] Sector CO 2 sourceEmissions [Gt] electricity carbon-basedp owerp lants 12.4 heavy industry productiono fcement, limestone,a nd hydrogen 3.9 transport road > air > ship > rail 6.0 > 0.9 > 0.8 > 0. [16][17][18] Thermocatalytic CO 2 conversion is also well known. Capturing CO 2 ,e ither from flue gases of industrial processes or directly from the atmosphere,i so ne such option.…”

“…[15] Plasma and plasma catalytic reactions are also gaining attention, especially CO 2 splitting and dry reforming of methane (DRM). [16][17][18] Thermocatalytic CO 2 conversion is also well known. For instance, DRM with CO 2 is used to produce syngas, which is then used for the production of hydrocarbonso ra lcohols through the Fischer-Tropsch synthesis (FTS).…”