On NO_xproduction and volatile organic compound removal in a pulsed microwave discharge in air

Abstract

The production of NO and NO 2 and the removal of 3-pentanone, as an example for volatile organic compounds (VOCs), in a pulsed microwave discharge in air, near atmospheric pressure has been studied. The influence of changing the pulse duration from 25 to 500 µs and of the pulse repetition rate from 10 to 500 Hz is reported. At a relatively high pressure of p = 800 mbar, plasma ignition is achieved by inserting BaTiO 3 pellets inside the microwave excitator. The concentrations of NO and NO 2 have been monitored by infrared tunable diode laser absorption spectroscopy. It was found that their concentrations increase monotonically with the average power injected into the plasma. Further, the efficiency of the pulsed microwave discharge for VOC oxidation, in this case of 1400 ppm of 3-pentanone in dry air, has been studied. The VOC removal efficiency has been determined using gas chromatography. The oxidative efficiency of the discharge was found to increase linearly with the pulse repetition rate as well as with the pulse duration, the power duty cycle ratio being the key parameter.

Nonthermal plasma activates catalyst: from current understanding and future prospects

“…Kuroki et al reported NOx formation problem from the decomposition of adsorbed xylene on zeolite using AC barrier discharge plasma in air [24]. Microwave (MW) plasma is also known to produce high concentration of NO and NO 2 (∼4000 ppm) when it is operated at air-like mixture [25]. The common factor for these two methods is high specific input energy up to several tens kJ L −1 .…”

Plasma Catalytical Reactors for Atmospheric Gas Conversions

“…Nevertheless, the ignition of the microwave plasma at atmospheric pressure is not as simple as with the DBD. In one setup the ignition of a microwave plasma is possible at a working pressure of 800 mbar with added BaTiO 3 pellets, which enhances the electric field strength at the edges of the pellets [71]. The pulsed microwave discharge is used for the decomposition of 200 ppm acetylene in air at 800 mbar.…”

Quantum cascade laser absorption spectroscopy – A new method to study molecular plasma components

“…Various precursor molecules like BCl 3 , BF 3 or B 2 H 6 are used to provide active boron-containing species in the plasmas. In particular Boron Trichloride (BCl 3 ) is a source gas of considerable interest in plasma research and industry since it is used for the surface modification of steel components in mechanical engineering and automotive industries as well as for plasma etching of semiconductor devices.…”