CO₂ Decomposition in CO₂ and CO₂/H₂ Spark‐like Plasma Discharges at Atmospheric Pressure

Abstract

In this work, a spark‐like plasma discharge is ignited in pure CO2 and in CO2/H2 mixtures to investigate CO formation. Power pulsing is used to limit arc formation to sustain a high current transient “spark‐like” plasma consisting of a mixed mode discharge comprising an initial current pulse (“spark”) followed by a longer‐lived glow mode thorough each half cycle of the applied voltage. In pure CO2, the efficiency ranged between 20–50 % for CO2 conversions between 9–18 % for gas residence times of 100–600 ms. Adding H2 as a co‐reactant was investigated for a wide range of mixture ratios. The outlet gas was found to produce O2‐free mixtures of CO/H2/CO2. Conversion rates in CO2/H2 mixtures are found to be similar to pure CO2 at equivalent residence times. The primary role of H2 as a co‐reactant is therefore found to be the removal of O2 formed during dissociation of CO2. The energy cost of this dilution resulted in reduced efficiency for CO2 conversion (from 41 to 18 %), which is correlated to the efficiency drop found for pure CO2 conversion at lower flows. Opportunities for optimising this small volume “unit‐cell” spark reactor are encouraged by the results presented. This approach could enable deployment of serial or parallel combinations of such reactors capable of dealing cost‐effectively with the conversion of the larger CO2 and CO2/H2 volumes required in future industry applications.

Thermal instability and volume contraction in a pulsed microwave N2 plasma at sub-atmospheric pressure

“…Note for the calculated conversion values given here, we take into account any changes in the (mass) density due to stoichiometric changes in the gas mix, i.e. the so-called expansion 'α' factor [83][84][85]. The specific energy input (SEI) is shown in figure 3(f ) along with the absorbed power.…”

CO2 conversion, utilisation and valorisation in gliding arc plasma reactors

“…With packing catalysts and at the suitable gas temperature, CO 2 can also be reduced to CH 4 with selectivity close to 100% in DBD plasma [103]. However, in the warm plasma, only RWGS occurred in a mixture of CO 2 and H 2 [104,105]. Although, it is believed that H 2 is an efficient reductant and can completely restrain the reverse reaction of (R1) by consuming O atom [31].…”

Spark Discharge Plasma-Enabled CO2 Conversion Sustained by a Compact, Energy-Efficient, and Low-Cost Power Supply

“…However, laboratory AC power supplies typically have high price due to the complex internal structures, which needs to be considered for the technoeconomic evaluation of the conversion performance. Commonly used NTPs for CO 2 dissociation include dielectric barrier discharge (DBD), 20,21 spark discharge, 22,23 gliding arc discharge (GAD), 24,25 and microwave (MW) discharge. 26,27 DBD plasma is one of the most easily applicable plasma technologies for commercialization.…”

“…Commonly used NTPs for CO 2 dissociation include dielectric barrier discharge (DBD), , spark discharge, , gliding arc discharge (GAD), , and microwave (MW) discharge. , DBD plasma is one of the most easily applicable plasma technologies for commercialization. − However, its low influx rate and energy loss through heat dissipation in dielectric materials limit the satisfying dissociation performance. GAD and MW plasmas with high power can achieve a high conversion rate while maintaining energy efficiency because of the absence of dielectric materials.…”