甲烷和氮气在微波等离子体下的转化研究

Study on conversion of methane and nitrogen under the microwave plasma

运用微波等离子体技术研究了甲烷和氮气的化学反应。考察了反应条件对产物选择性和甲烷转化率的影响。甲烷转化率随着微波输入功率的增大和反应物配比 (n(CH4) /n(N2 ) )的减小而增大 ;在最佳条件下 ,甲烷转化率达96 2 %。HCN选择性随着n(CH4) /n(N2 )比的增大而降低 ;在n(CH4) /n(N2 ) <0 995时 ,HCN为主产物 ,且HCN的选择性随微波输入功率的增大而减小 ,在最佳条件下 ,HCN选择性达 91 4% ;在n(CH4) /n(N2 ) >0 995时 ,C2 H2 为主产物 ,然而HCN选择性随着微波输入功率的增大而增加。C2 H2 选择性随着微波输入功率的增大而增加 ,随着n(CH4) /n(N2 )的增大出现极大值 ;在最佳条件下 ,C2 H2 选择性达 72 77%。C2 H2 和C2 H6 的选择性随着微波输入功率的减小和n(CH4) /n(N2 )的增大而增加。对甲烷、氮气等离子体的电子温度和电子密度进行了诊断 ,并运用自由基反应理论解释了反应条件对甲烷转化率和产物选择性的影响。

The reactions of CH 4 and N 2 were studied by using the microwave plasma technology.Reaction factors affecting the conversion of methane and the selectivity of products were researched.The conversion of methane increased with microwave input power increasing and mol. ratio of reactants ( n (CH 4)/ n (N 2)decreasing;in the optimal operation,the conversion of methane was up to 96 2%. Selectivity of HCN decreased with n (CH 4)/ n (N 2)increasing.At the n (CH 4)/ n (N 2)<0 995,HCN was main product and,selectivity of HCN decreased with microwave input power increasing.In the optimal operation,the selectivity of HCN was up to 91 4%.At the n (CH 4)/ n (N 2)>0 995,acetylene was main product,however,selectivity of HCN increased with microwave input power increasing.selectivity of acetylene increased with microwave input power increasing and appeared a maximum with n (CH 4)/ n (N 2)increasing;in the optimal operation,Selectivity of acetylen was up to 72 77% Selectivity of ethylene and ethane increased with microwave input powere decreasing and n (CH 4)/ n (N 2)increasing.Electron temperature and density in the plasma of CH 4 and N 2 were diagnosed by a floating double electrostatic probes.According to radical reaction theory,the varying laws of conversion of methane and the selectivity of products with affecting factors were explained in the plasma chemical reactions of CH 4 and N 2.