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 (CO2) 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 CO2, O2, H2O, and N2 gases are 2.75%, 18%, 1%, and the balance, respectively. The results reveal that CO2 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 CO2 to CO, which can be utilized in the production of combustion fuels, is possible. [ABSTRACT FROM AUTHOR]