Carbon Dioxide Decomposition by a Parallel-Plate Plasma Reactor: Experiments and 2-D Modelling

Abstract

The applicability of high voltage electrical discharges for the decomposition of CO2 has been extensively demonstrated. In this study, a new AC parallel-plate plasma reactor is presented which was designed for this purpose. Detailed experimental characterization and simulation of this reactor were performed. Gas chromatography of the exhaust gases enabled calculation of the CO2 conversion and energy efficiency. A conversion factor approximating 25% was obtained which is higher in comparison to existing plasma sources. Optical emission spectroscopy enabled the determination of the emission intensities of atoms and molecules inside the plasma and characterization of the discharge. The Stark broadening of the Balmer hydrogen line Hβ was used for the estimation of the electron density. The obtained densities were of the order of 5 × 1014 cm−3 which indicates that the electron kinetic energy dominated the discharge. The rotational, vibrational, and excitation temperatures were determined from the vibro-rotational band of the OH radical. A 2-temperature plasma was found where the estimated electron temperatures (~18,000 K) were higher than the gas temperatures (~2000 K). Finally, a 2-D model using the fluid equations was developed for determining the main processes in the CO2 splitting. The solution to this model, using the finite element method, gave the temporal and spatial behaviors of the formed species densities, the electric potential, and the temperatures of electrons.

Influence of the argon admixture on the reactive oxide species formation inside an atmospheric pressure oxygen plasma jet

“…(i) the Van der Waals broadening, Δλ van der Waals , given by the following expression calculated as in ref. 41 , considering for this case H 2 O molecules as perturbers of H atoms emitters 42 , 46 : where µ is the reduced mass of the colliding particles (µ = 0.94737 for H/H 2 O collision), λ is the wavelength of the H β line (486.1 nm), α is the molecular polarizability of the H 2 O disturbing particles (α = 1.43 × 10 –24 cm 3 ), 〈R 2 〉 is the difference of the square radius of the upper and lower levels of H β transition, T g is the gas temperature in K, and P is the pressure (1 atm for atmospheric pressure).…”

“…The applied boundary conditions for the wire-to-multiwire dielectric discharge are similar to those that can be found in the existing literature 40 . The following boundary condition is used to account for the particles flux in wall: where n is the normal vector pointing toward the tube wall and, v th ( i ) is the thermal velocity of particles 41 : and the number a i is defined by: …”

“…For electrons, as a special case, the particles flux due to secondary electron emission (SEE) is added to the system and is defined as follows 40 : where γ p are the SEE coefficients, which defines the average number of electrons emitted per impact of ions p on the tube wall. Similarly, boundary condition for electron energy is 41 : …”

Experimental Study of a Rotating Electrode Plasma Reactor for Hydrogen Production from Liquid Petroleum Gas Conversion

“…The detection of N 2 , NH, CO 2 , CO, and CN bands confirmed the existence of nitrogen and oxygen in the discharge tube. The reactions of the oxygen, hydrogen, and nitrogen of air with the carbon produced in the LPG dissociation explain the detected species [16,19]. These species could have been coming from the air entrance by the bottom part, impurities of the LPG gas and sputtering of the dielectric polyamide layer.…”

“…The production of species by the reactions of Equation ( 5) and its excitation was also increased. air with the carbon produced in the LPG dissociation explain the detected species [16,19]. These species could have been coming from the air entrance by the bottom part, impurities of the LPG gas and sputtering of the dielectric polyamide layer.…”