Dry Reforming of Methane in a Gliding Arc Plasmatron: Towards a Better Understanding of the Plasma Chemistry

Abstract

Dry reforming of methane (DRM) in a gliding arc plasmatron is studied for different CH fractions in the mixture. The CO and CH conversions reach their highest values of approximately 18 and 10 %, respectively, at 25 % CH in the gas mixture, corresponding to an overall energy cost of 10 kJ L (or 2.5 eV per molecule) and an energy efficiency of 66 %. CO and H are the major products, with the formation of smaller fractions of C H (x=2, 4, or 6) compounds and H O. A chemical kinetics model is used to investigate the underlying chemical processes. The calculated CO and CH conversion and the energy efficiency are in good agreement with the experimental data. The model calculations reveal that the reaction of CO (mainly at vibrationally excited levels) with H radicals is mainly responsible for the CO conversion, especially at higher CH fractions in the mixture, which explains why the CO conversion increases with increasing CH fraction. The main process responsible for CH conversion is the reaction with OH radicals. The excellent energy efficiency can be explained by the non-equilibrium character of the plasma, in which the electrons mainly activate the gas molecules, and by the important role of the vibrational kinetics of CO . The results demonstrate that a gliding arc plasmatron is very promising for DRM.

Dry Reforming of Methane in DBD Plasma over Ni‐Based Catalysts: Influence of Process Conditions and Support on Performance and Durability

“…[15][16][17] Nonthermal plasma (NTP) approach has been used as an alternative to thermocatalytic methods. Various NTP systems such as corona discharges, [18] atmospheric plasma jet, [19] gliding arcs, [20][21][22] glow discharge, [23] and dielectric barrier discharges (DBDs) [24][25][26] have been tested for DRM and CO 2 mitigation. Among all, DBD attracted more attention due to the uniform distribution of microdischarges, presence of high energetic electrons, capability of initiating the reaction under ambient conditions, etc.…”

Controlling the Reduction Extent for Metal Catalysts

“…Ni catalysts are probably among the most commonly used due to their effectiveness and low costs, they are versatile and have been used in numerous reactions . One of the reactions is dry reforming of methane (DRM), in which two greenhouse gases (CH 4 and CO 2 ) are converted to valuable syngas (H 2 and CO) . Ni catalysts for DRM, also true for other reactions, are prepared by various methods, e. g., impregnation, co‐precipitation, sol‐gel, polymerization, hydrothermal,, and more recently plasma treatment,, and atomic layered deposition ,.…”

“…[8][9][10][11][12] One of the reactions is dry reforming of methane (DRM), in which two greenhouse gases (CH 4 and CO 2 ) are converted to valuable syngas (H 2 and CO). [13][14][15][16][17] Ni catalysts for DRM, also true for other reactions, are prepared by various methods, e. g., impregnation, [18][19][20][21] coprecipitation, [22][23][24][25] sol-gel, [26][27][28] polymerization, [29] hydrothermal, [30,31] and more recently plasma treatment, [32,33] and atomic layered deposition. [34,35] A reduction process usually follows to obtain active metal phase.…”

Optimisation of CH4 and CO2 conversion and selectivity of H2 and CO for the dry reforming of methane by a microwave plasma technique using a Box–Behnken design

“…Plasma DRM technology is considered the best way to convert CO 2 and CH 4 to synthesis gas . Plasma, the fourth state of matter, is a partially ionised gas mixture consisting of ions, atoms, electrons, molecules, free radicals, neutral by‐products, and photons . Generally, the plasma process is divided into two main methods: The first is cold plasma (nonthermal plasma) discharge including dielectric barrier discharge, corona discharge, atmospheric pressure glow discharge, gliding arc discharge, microwave discharge, and spark discharge .…”

“…In the nitrogen‐plasma process, CO 2 and CH 4 conversion and selectivities of H 2 and CO are affected by many factors such as feed gas flow rate, CO 2 :CH 4 ratio, reactor design, residence time, and discharge power . Several authors have proved that the effect of feed gas flow rates of CO 2 , CH 4 , and N 2 is an effective factor in the performance of the plasma process. First, Cleiren et al reported that the feed flow rate affects the conversion, selectivity, yield, and syngas (H 2 /CO) ratio.…”