Nonthermal plasma chemical processing of bromomethane

Nonthermal plasma chemical decomposition of bromomethane (CH3Br) was invest igated with a coaxial type packed-bed plasma reactor. It has been demonstra ted that plasma chemical processing is an effective approach to decompose C H3Br in a wide concentration range. It has been shown that CH3Br decomposit ion reactivity depends on reactor operating factors such as background gas, O-2 concentration, and humidification. Higher decomposition efficiencies c an be obtained in dry N-2. However, organic byproducts such as BrCN are con currently produced under deaerated conditions. Water suppresses CH3Br decom position and also affects the yields of COx (CO and CO2) and organic byprod ucts due to the involvement of some active species generated from water. Th e presence of O-2 retards CH3Br decomposition by quenching high-energy elec trons, while it suppresses organic byproducts and improves COx yield. The r eacted carbons in CH3Br are recovered as COx almost quantitatively in air. Higher CO2 selectivities cannot be achieved by increasing O-2 concentration . NOx formation, which is accompanied by CH3Br decomposition, can be effect ively suppressed by decreasing O-2 concentration down to 2%. Furthermore, r eaction mechanisms are discussed by comparing the reactivities of CH3Br and its congeners.