Experimental Studies On Methane Chlorination And Dichloromethane Decomposition By Pulsed Corona Combined With Catalysis

The first part of this study is to convert methane to chloromethane with carbon tetrachloride by pulsed electrical discharge in a wire-cylinder reactor.The influences of operation parameters such as frequency and carrier gases on the methane chlorination were investigated.Experimental results showed that the main reaction products from the reaction of methane and carbon tetrachloride are HCl and chloromethanes?CMS?which include CH3C1,CH2Cl2 and CHCl3.It was found that the products of CH3Cl and CH2Cl2 mainly come from methane conversion.The conversion of CH₄ increased with the increase of input energy to the reactor;When the input peak pulsed voltage was increased to 22.5 kV,the conversion of methane tended to be stable;It was also found that CH2Cl2 was the main product from the reaction and the proportion of CH2Cl2 in CMS decreases with the decrease of applied voltage;Both the conversion of methane and the production of CH2C12 increased with the decrease of the molar ratio of CH₄ to CCl₄;With the same applied voltage,the conversion of methane in wire-tube reactor was higher than that in needle-plate reactor;Methane conversion and CMS production increased slightly in wire-tube reactor combined with TiO2;However,methane conversion increased more than 10%with the UV lamp radiation.The decomposition of methylene chloride?DCM?in a wire-in-tube pulsed corona reactor was also experimentally investigated.Experimental results showed a maximum removal with the addition of 2%O2 into nitrogen.But,when O2 concentration exceeded 4%in gas stream,the decomposition of DCM decreased.This result also showed that the main gaseous products of DCM decomposition in were N2 are HCl,Cl2 and CCl₄,When the O2 was added in sample gas,the final decomposition products were CO2,CO,COCl2,H2O and O3.The decomposition of methylene chloride increased with coating a layer of Ti02 on the surface of grounding electrode in the rector;The decomposition ratio of DCM in Ar gas was higher than that in the N2 gas;Increasing the concentration of DCM results in decreasing the removal rate of DCM in plasma;The removal amount of DCM increased with the increase of DCM concentration.When the concentration of DCM increased to 5000 mg·m-3,the removal amount of DCM tended to be stable.