锯—板脉冲电晕放电协同复合催化剂脱除氮氧化物研究

发布时间：2018-05-15 06:45

本文选题：电晕放电 + 等离子体　；参考：《江西理工大学》2017年硕士论文

【摘要】：随着人们对大气环境越来越重视,氮氧化物(NO_x)作为目前主要的气态污染,不仅对人类健康造成危害,对环境也有极大的破坏作用,其治理技术受到越来越多的关注。低温等离子体协同催化剂技术脱除氮氧化物因其工艺简单、效率高、能耗低等优点引起学者的广泛研究,提高等离子体在富氧条件下对NO_x的脱除有很大的应用前景,还需进一步研究。本文以氮氧化物中主要成分NO为处理对象。采用锯-板式脉冲电晕放电反应器,首先对其的结构进行优化,在此基础上,分析电气参数和气体参数对氮氧化物脱除的影响。然后协同催化剂进行氮氧化物脱除实验,使用5A分子筛作为催化剂载体,分析了负载不同活性物(Cr、Cu、Mn、Fe)和掺杂稀土元素Ce对催化活性影响,运用SEM、XRD技术对催化剂进行表征,确定了最佳的负载量。最后分析了添加不同种类和浓度的还原剂(CH4、C2H2)对氮氧化物脱除的影响。实验结果表明:锯-板脉冲电晕放电等离子体反应器中可以产生相对均匀的电晕放电,且在较高电压下不易发生火花放电,有较好的放电稳定性;在锯数为4,锯板间距为2cm,锯锯间距2cm,锯齿间距6mm时,可以兼顾脉冲电晕放电等离子体有较高能量和较大的体积;增加脉冲电压有利于提高NO的转化率和NO_x的脱除率,促进NO氧化为NO_2,脉冲重复频率达到80 Hz,脱除效果最佳;随着O_2浓度增加,NO的转化率和NO_x的脱除率均逐渐下降,然后趋于稳定,O_2的存在使NO还原过程受阻;H2O加入可以产生活性更强的自由基·H、·OH以及·HO_2,提高脱除率;8%Fe/5A分子筛催化剂的效果最佳,NO的转化率达到46.3%,NO_x脱除率最高为32.8%;适量掺杂稀土元素Ce后的Fe/5A分子筛催化剂活性提高,脉冲放电协同3%Ce-Fe/5A分子筛催化剂的NO的转化率和NO_x脱除率分别为49.7%、37.3%;加入还原剂可以提高脉冲放电等离子体协同Ce-Fe/5A分子筛催化剂的NO_x的脱除率,且其浓度越高效果越好,C2H2的效果要好于CH4,当加入1000 ppm C2H2后,NO转化率提高到57.4%,NO_x脱除率提高到43.6%。
[Abstract]:With more and more attention being paid to the atmospheric environment, no _ x (no _ x), as the main gaseous pollution at present, not only causes harm to human health, but also has a great damage to the environment. Therefore, more and more attention has been paid to its treatment technology. The removal of nitrogen oxides by low temperature plasma cooperative catalyst technology has attracted extensive research due to its advantages of simple process, high efficiency and low energy consumption. It has a great application prospect to improve plasma removal of NO_x under oxygen-enriched conditions. Further study is needed. In this paper, no, the main component of nitrogen oxides, was used as the treatment object. The structure of saw plate type pulse corona discharge reactor was optimized, and the influence of electrical parameters and gas parameters on nitrogen oxide removal was analyzed. The catalytic activity was analyzed by using 5A molecular sieve as the catalyst carrier, and the effect of the supported on the catalytic activity was analyzed. The catalyst was characterized by means of SEM- XRD. The optimal load is determined. Finally, the effects of different kinds and concentrations of reducing agent (Ch _ 4, C _ 2H _ 2) on the removal of nitrogen oxides were analyzed. The experimental results show that a relatively uniform corona discharge can be produced in a saw-plate pulsed corona discharge plasma reactor, and spark discharge is not easy to occur at a higher voltage and has good discharge stability. When saw number is 4, saw plate spacing is 2 cm, saw tooth spacing is 6mm, the pulse corona discharge plasma has higher energy and larger volume, and increasing pulse voltage can increase no conversion rate and NO_x removal rate. Promoting no oxidation to no _ 2, pulse repetition frequency reaching 80 Hz, the best removal effect; with the increase of O _ 2 concentration, the conversion rate of no and the removal rate of NO_x decreased gradually. Then the presence of O _ 2 tends to stabilize the process of no reduction by adding H _ 2O to produce more active free radicals H, OH and Ho _ 2. The best catalyst for increasing the removal rate is 8 / 5A molecular sieve catalyst. The best conversion of no is 46.3% no. The highest is the removal rate of no. The catalytic activity of Fe/5A molecular sieve with proper amount of rare earth element ce was increased. The conversion rate of no and the removal rate of NO_x were 49.7% and 37.3%, respectively. The addition of reducing agent could increase the removal rate of NO_x in the catalyst of Ce-Fe/5A molecular sieve with pulsed discharge plasma and Ce-Fe/5A / 5A molecular sieve catalyst. The higher the concentration, the better the effect of C _ 2H _ 2 is better than that of Ch _ 4. After adding 1000 ppm C2H2, the conversion rate of no is increased to 57.4% and the removal rate of no _ 2H _ 2 is increased to 43.6%.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X701

【参考文献】