CO2 Concentration Using Adsorption and Nonthermal Plasma Desorption

Air-pollutant and greenhouse gas emissions typically have high gas flow rates and low concentrations (in ppm ~% levels, 1% = 10 000 ppm). The bulky equipment required for direct treatment of high-flow-rate low-concentration exhaust gases result in high-energy consumption and prohibitive operating costs. As such, the objective of this study is to convert high-flow-rate low-concentration exhaust gases into low-flow-rate high-concentration gases. This is achieved by desorbing the gas from an adsorbent by applying an atmospheric plasma inside a nonthermal plasma (NTP) reactor. This paper focuses on carbon dioxide (CO
₂
) concentration (condensation) via this method. The adsorbent consists of spherical ~2-mm-diameter molecular-sieve pellets of zeolite. Plasma desorption is performed by applying nanosecond high-voltage pulses (peak voltage ~35 kV, pulse frequency = 140-350 Hz, and pulse width ~600 ns) to the plasma reactor. A gas flow rate of 4 L/min is used and the concentrations of CO
₂
, O
₂
, H
₂
O, and N
₂
gases are 2.75%, 18%, 1%, and the balance, respectively. The results reveal that CO
₂
can be desorbed effectively and more rapidly in a repeated adsorption and NTP desorption process than during the thermal process. Moreover, for the same electric power, the peak concentrations (typically 13%) are higher in the NTP desorption process than in the thermal process at equal electric power. These results indicate that the efficient NTP dissociation of CO
₂
to CO, which can be utilized in the production of combustion fuels, is possible.