添加气对直流等离子体转化甲烷制C_2烃的影响

在低温(300~500 K)常压下,考察了不同性质的添加气二氧化碳(CO2)、氩气(Ar)和氢气(H2)(添加气摩尔浓度0%~80%)对直流冷等离子体转化甲烷制C2烃反应的影响。研究结果表明:CO2虽能在一定程度上提高甲烷转化率,但不利于C2烃的生成;Ar和H2有利于提高甲烷的转化率和C2烃选择性;添加气体对C2产物的分布研究发现:CO2有利于C2H4的生成,添加气Ar不影响产物C2烃的分布,H2在一定程度上促进了C2H4的生成;在实验考察范围内,增加体系的能量密度有利于提高甲烷的转化率;CH4-CO2体系中,C2烃选择性随能量密度的增加而升高;CH4-Ar体系中,C2烃选择性随能量密度的增加变化不大:CH4-H2体系中,C2烃的选择性随能量密度的增加呈现先升后降的趋势。

Effect of Appended Gas on Methane Converting to C2 Hydrocarbons under Direct Current Plasma

At low temperature(300～500 K) and atmospheric pressure,the reaction of methane to C_2 hydrocarbons in the presence of appended gas(carbon dioxide,argon and hydrogen)under direct current plasma was investigated.The molar density of the appended gases varied from 0% to 80% in the experiment.The results showed that the selectivity of C_2 hydrocarbons was decreased with the increase of the quantity of carbon dioxide,though the conversion of CH_4 increased slightly.Both the conversion of CH_4 and the selectivity of C_2 hydrocarbons were increased in the presence of argon and hydrogen.The experiments also showed that the molar density of ethylene in the C_2 hydrocarbons increased distinctly when carbon dioxide concentration increased.Argon and hydrogen caused the distribution of C_2 hydrocarbons to change slightly.The selectivity of C_2 hydrocarbons increased with energy density in CH_4-CO_2 system,and it was not affected in CH_4-Ar system. A peak appeared in CH_4-H_2 system with increasing energy density under the experimental conditions.