介质阻挡放电和火花放电转化甲烷的研究
发布时间：2018-12-17 19:06
【摘要】：随着石油资源的日益枯竭和环境问题日益严重,以CH4为原料生产化学品的新途径越来越受到国内外学者的广泛关注。本文主要进行低温等离子体甲烷转化制高碳烃和甲烷重整制合成气的研究,并重点对比了介质阻挡放电和火花放电两种放电形式对于甲烷转化的差异。得到如下结果和结论：在甲烷转化制高碳烃的研究中,介质阻挡放电条件下产物分布范围较广,主要产物为C2H6、C3H8和C4H1o饱和烷烃,选择性分别为46.9%、23.4%和14.2%,系统考察了进料流量、放电功率、放电间距、填充介质对甲烷转化率和产物选择性的影响,结果表明减小甲烷进料流量、提高放电功率、减小放电间距、填充小颗粒介质均能够提高甲烷转化率,并在一定程度上调节产物分布。火花放电转化甲烷所得的主要产物为C2H2,其选择性超过95%,但是火花放电积碳快,放电稳定性较差；通过添加H2、N2、Ar、He、02和NH3等添加气得出：H2、He和NH3对C2烃的分布具有一定调节作用,02对CH4没有氧化偶联作用,但它可通过生成CO而显著影响产物分布；Ar、He、H2会提高甲烷火花放电的转化能量效率,02、N2和NH3会降低CH4火花放电的转化能量效率；添加H2和02能够延缓积碳速度,提高放电稳定性,相比之下,02添加气对改善放电稳定性的效果最好。最后通过产物分析和发射光谱(OES)数据,推断出介质阻挡放电和火花放电转化甲烷可能的活化途径。甲烷转化制合成气的研究中,在反应物的转化率和合成气(CO+H2)产物选择性方面,火花放电都要优于介质阻挡放电。CH4-CO2火花放电制合成气时存在反应器积碳问题,反应不能长时间稳定进行,添加02能够彻底摆脱CH4-CO2火花放电制合成气时的反应器结炭问题,而且CH4-O2-CO2三组分气体火花放电制合成气方法能通过改变三种反应气体的进料比例而灵活调节产物H2/CO比。在CH4流量20 mL/min、O2流量10mL/min、CO2流量12.38 mL/min、注入功率为28W的条件下进行的CH4-O2-CO2火花放电连续运转实验,在所考察的100 h内,CH4、CO2的转化率稳定,其平均值分别为61.73%和32.39%,产物中H2/CO的比例保持在1.0左右；在CH4流量20 mL/min、O2流量10mL/min、CO2流量0.77 mL/min、注入功率为28 W的条件下进行的CH4-O2-CO2火花放电连续运转实验,在所考察的100 h内,CH4、CO2的转化率稳定,其平均值分别为63.87%和37.50%,产物中H2/CO的比例保持在2.0左右。
[Abstract]:With the increasingly depletion of petroleum resources and the increasingly serious environmental problems, the new way to produce chemicals using CH4 as raw material has attracted more and more attention from domestic and foreign scholars. In this paper, the methane conversion from low temperature plasma to high carbon hydrocarbon and methane reforming to syngas are studied, and the differences between dielectric barrier discharge and spark discharge for methane conversion are compared. The results and conclusions are as follows: in the study of methane conversion to high carbon hydrocarbons, the distribution range of the products under dielectric barrier discharge is relatively wide. The main products are C _ 2H _ 6C _ 3H _ 8 and C4H1o saturated alkanes with selectivity of 46.9, respectively. The effects of feed flow rate, discharge power, discharge spacing and filling medium on methane conversion and product selectivity were investigated systematically. The results showed that the feed flow rate of methane was reduced, the discharge power was increased, and the discharge distance was reduced. Filling with small particle media can increase methane conversion and adjust the distribution of products to some extent. The main product of methane conversion from spark discharge is C _ 2H _ 2, its selectivity is more than 95%, but the spark discharge has fast carbon accumulation and poor discharge stability. By adding H _ 2H _ 2N _ 2N _ 2H _ 2H _ 2O _ 2 and NH3 gas, it was found that H _ 2H _ 2H _ 2 and NH3 could regulate the distribution of C _ 2 hydrocarbon to some extent, and that O _ 2 had no oxidative coupling effect on CH4, but it could significantly influence the distribution of products by forming CO. Ar,He,H2 can improve the conversion energy efficiency of methane spark discharge, while 02 N 2 and NH3 can decrease the conversion energy efficiency of CH4 spark discharge. The addition of H2 and 02 can delay the carbon deposition rate and improve the discharge stability. Finally, the possible activation pathways of methane conversion from dielectric barrier discharge and spark discharge were inferred by product analysis and emission spectrum (OES) data. In the research of methane conversion to syngas, the spark discharge is superior to dielectric barrier discharge in the conversion of reactants and the selectivity of CO H2 products. The reaction can not be carried out stably for a long time. Adding 02 can completely get rid of the problem of reactor coking when CH4-CO2 spark discharge is used to produce syngas. Moreover, the CH4-O2-CO2 three-component gas spark discharge method can flexibly adjust the H2/CO ratio by changing the feed ratio of the three reaction gases. The continuous operation experiment of CH4-O2-CO2 spark discharge was carried out under the condition of CH4 flow rate of 20 mL/min,O2, flow rate of 10 mL / min CO 2 flow rate of 12.38 mL/min, injection power of 28 W, and the conversion rate of CH4,CO2 was stable within 100 h. The average values were 61.73% and 32.39%, respectively, and the proportion of H2/CO in the product remained about 1.0. The continuous operation experiment of CH4-O2-CO2 spark discharge was carried out under the condition of CH4 flow rate of 20 mL/min,O2, flow rate of 10 mL / min CO 2 flow rate of 0.77 mL/min, injection power of 28 W, and the conversion rate of CH4,CO2 was stable within 100 h. The average values were 63.87% and 37.50%, respectively, and the proportion of H2/CO in the product remained about 2.0.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE665.3
本文编号：2384668
[Abstract]:With the increasingly depletion of petroleum resources and the increasingly serious environmental problems, the new way to produce chemicals using CH4 as raw material has attracted more and more attention from domestic and foreign scholars. In this paper, the methane conversion from low temperature plasma to high carbon hydrocarbon and methane reforming to syngas are studied, and the differences between dielectric barrier discharge and spark discharge for methane conversion are compared. The results and conclusions are as follows: in the study of methane conversion to high carbon hydrocarbons, the distribution range of the products under dielectric barrier discharge is relatively wide. The main products are C _ 2H _ 6C _ 3H _ 8 and C4H1o saturated alkanes with selectivity of 46.9, respectively. The effects of feed flow rate, discharge power, discharge spacing and filling medium on methane conversion and product selectivity were investigated systematically. The results showed that the feed flow rate of methane was reduced, the discharge power was increased, and the discharge distance was reduced. Filling with small particle media can increase methane conversion and adjust the distribution of products to some extent. The main product of methane conversion from spark discharge is C _ 2H _ 2, its selectivity is more than 95%, but the spark discharge has fast carbon accumulation and poor discharge stability. By adding H _ 2H _ 2N _ 2N _ 2H _ 2H _ 2O _ 2 and NH3 gas, it was found that H _ 2H _ 2H _ 2 and NH3 could regulate the distribution of C _ 2 hydrocarbon to some extent, and that O _ 2 had no oxidative coupling effect on CH4, but it could significantly influence the distribution of products by forming CO. Ar,He,H2 can improve the conversion energy efficiency of methane spark discharge, while 02 N 2 and NH3 can decrease the conversion energy efficiency of CH4 spark discharge. The addition of H2 and 02 can delay the carbon deposition rate and improve the discharge stability. Finally, the possible activation pathways of methane conversion from dielectric barrier discharge and spark discharge were inferred by product analysis and emission spectrum (OES) data. In the research of methane conversion to syngas, the spark discharge is superior to dielectric barrier discharge in the conversion of reactants and the selectivity of CO H2 products. The reaction can not be carried out stably for a long time. Adding 02 can completely get rid of the problem of reactor coking when CH4-CO2 spark discharge is used to produce syngas. Moreover, the CH4-O2-CO2 three-component gas spark discharge method can flexibly adjust the H2/CO ratio by changing the feed ratio of the three reaction gases. The continuous operation experiment of CH4-O2-CO2 spark discharge was carried out under the condition of CH4 flow rate of 20 mL/min,O2, flow rate of 10 mL / min CO 2 flow rate of 12.38 mL/min, injection power of 28 W, and the conversion rate of CH4,CO2 was stable within 100 h. The average values were 61.73% and 32.39%, respectively, and the proportion of H2/CO in the product remained about 1.0. The continuous operation experiment of CH4-O2-CO2 spark discharge was carried out under the condition of CH4 flow rate of 20 mL/min,O2, flow rate of 10 mL / min CO 2 flow rate of 0.77 mL/min, injection power of 28 W, and the conversion rate of CH4,CO2 was stable within 100 h. The average values were 63.87% and 37.50%, respectively, and the proportion of H2/CO in the product remained about 2.0.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE665.3
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