Characterization of the Conversion of Benzene to Nitrosobenzene in a Helium Low-Temperature Plasma

Abstract

The ionization of benzene (C6H6) through helium low-temperature plasma (He-LTP) offers a promising solution to the pervasive issue of its pollution in our daily lives. This study aimed to optimize the conditions for generating specific compounds, namely M+ and [M + 30]+, during the ionization of benzene in low-temperature plasma (LTP) with determination by mass spectrometry (MS). When the discharge voltage is 2.5 kV, a sample gas to discharge gas flow rate ratio of 2:3 is the best condition for generating M+ ions. When the discharge voltage is 3.5 kV, the gas flow rate ratio of 1:3 is the most suitable for generating [M + 30]+ ions. The LTP exhibits optimal ionization efficiency at a total gas flow rate of 40 mL/min. Additionally, we conducted a comparative analysis on the optical emission of benzene in the LTP which revealed the generation of free radicals associated with N, H, and O. The produced nitroso radical (ON•) combines with ionized benzene to yield the [M + 30]+ ion, identified to be nitrosobenzene. Notably, 95% conversion was achieved in the transformation from benzene to nitrosobenzene.