冷等离子体裂解甲烷制C_2烃动力学分析及模拟

研究在冷等离子体条件下甲烷裂解并偶联产生C2烃的反应机理。应用碰撞理论和玻尔兹曼分布计算了CH4被高能电子裂解为CH3,CH2,CH和H等自由基的速率常数与电子温度的关系。常温常压下,对49个反应构成的复杂体系进行动力学分析,数值模拟了不同的电子密度及电子温度下,甲烷、乙烯、乙炔等12种粒子的密度随反应时间的演变。结果表明:电子密度及电子温度越大,甲烷的转化率越高;当电子温度为1 5eV,电子密度在1011～1013cm-3之间变化时,甲烷的转化率接近100%,C2烃的总选择性接近100%,达到平衡的时间为35ms到650ms。

Kinetics Analysis and Simulation Involved in Cracking and Conversion of Methane to C2 Hydrocarbons in Cold Plasma

The reaction mechanism of methane cracking and conversion to C_2 hydrocarbons in cold plasma was investigated. The relation between electronic temperature and rate constants in dissociation of CH_4 by high energy electron into CH_3,CH_2,CH and H etc. was calculated through Boltzmann distribution and collision theory. The complex system which consisted of 49 reactions under normal condition was analyzed based on kinetics. Numerical simulation involved in the steady state densities of 12 kinds of species including methane, acetylene, ethylene etc. and their time dependence was implemented at different electron temperature and density. The calculation indicated the conversion of methane increased with the electron density or temperature increasing. When electron temperature was 1.5eV and electron density was ranged from 1011 to 1013 cm~(-3) , conversion of methane and selectivity of C_2 hydrocarbons both approached 100%, and equilibrium time ranged from 35ms to 650ms.