【作者】 高超；

【导师】 郭洪臣；

【作者基本信息】 大连理工大学 ， 化学工程（专业学位）， 2015， 硕士

【摘要】 过氧化氢(H202)是一种重要的绿色氧化剂,广泛应用于化学品合成、纺织品漂白、环境保护、航天及军工等领域。H2/02等离子体法能够直接合成高纯度高浓度H202,是一种极具吸引力的H202合成新途径。本文详细研究了等离子体反应器结构和反应条件对H2/02等离子体合成H202反应结果的影响：1、考察了反应器结构如高压电极外径、高压电极介质厚度、放电区长度、高压电极材料和接地电极液体导电率对H2/02等离子体合成H202的影响,包括02转化率、H202选择性和H202收率,并研究了其影响反应结果的原因。优选出最佳高压电极外径、高压电极介质厚度和放电区长度为4.0 mm、1.0mm和250mm,最佳高压电极材料为Ni粉,最佳接地电极液体电导率为1200μs/cm。通过分析得出最佳放电电流值为30 mA。2、考察了冷却循环水温度和原料停留时间对02转化率、H202选择性和H202收率的影响。并利用发射光谱仪和示波器对不同条件下H2/02等离子体进行诊断。得出最佳的冷却循环水温度为24℃,最佳的原料停留时间为1～2 s。通过发射光谱和示波器诊断结果得出冷却循环水主要通过改变H2/02等离子体中的活性物种来影响反应结果,原料停留时间主要通过改变电子密度和平均电子能量来影响反应结果。3、研究了添加气态氧化物分子(H2O、CO和C02)对H2/02等离子体合成H202有显著的影响。得出CO和C02的促进作用较弱,H20分子对促进合成H202的效果明显。在18 ml/min H2O添加量时,在放电频率12.8 kHz、放电功率40 W、H2气速210ml/min、O2气速9.3 ml/min、循环水温度4℃及放电时间60 mm条件下,与不添加H20分子相比,02转化率由43.5%提高到83.7%,H202选择性维持在73.5%,H202收率由32.0%提高到61.6%。通过发射光谱、示波器及文献研究得出H20分子的加入既能增大电子密度,促进H2和02的转化,同时也能加速一些自由基反应,从而提高H202的收率。更多还原

【Abstract】 Hydrogen peroxide (H2O2) is widely used in chemical synthesis, textile bleaching, environmental protection, aerospace and military fields as an important green oxidant. H2/O2 plasma method is a new way that can synthesize high purity and concentrated H2O2.In this paper, the effects of plasma reactor structure and reaction conditions on the synthesis of H2O2 were studied in detail.Effects of reactor structure such as outer diameter of the high voltage electrode, thickness of high voltage electrode dielectric, length of discharge zone, material of high voltage electrode and conductivity of grounding electrode on synthesis of H2O2 through H2/O2 plasma were investigated. The mechanism of how the reactor structure affect the reaction result was also studied. The optimized outer diameter of high voltage electrode, thickness of high voltage electrode dielectric and length of discharge zone were about 4.0 mm,1.0 mm and 250 mm, respectively. The optimized material of high voltage electrode was Ni powder, and conductivity of grounding electrode was about 1200 μs/cm. It is also summarized that the optimized discharge current was about 30 mA.Reaction conditions such as temperature of circulating-cooling water and residence time of raw gas were investigated. The optimum temperature of circulating-cooling water was about 24℃ and the optimum residence time of raw gas was in the range of 1-2 seconds. Temperature of circulating-cooling water influences the reaction results mainly through changing the active species of H2/O2 plasma; Residence time of raw gas affect the reaction results mainly via altering the electron density and average electron energy of H2/O2 plasma.Effect of adding gaseous oxide molecules such as CO, CO2 and H2 on synthesis of H2O2 was studied in detail. The promotion effect of H2O to synthesis of H2O2 was significant, but the effects of CO and CO2 were weak. In the condition of 18 ml/min H2O flow rate,12.8 kHz discharge frequency,40 W discharge power,210 ml/min H2 flow rate,9.3 ml/min O2 flow rate,4℃ circulating-cooling water temperature,60 minutes reaction time, the conversion of O2 increased from 43.5% to 83.7%, the selectivity of H2O2 increased from 73.5% to 73.6%, the yield of H2O2 increased from 32.0% to 61.6%, compared with the condition of non H2O. The results of oscilloscope, optical emission spectra and literatures show that, H2O molecules can not only increase the electron density to promote the activation of H2 and O2, but also accelerate some radical reaction to synthesize H2O2. These two reasons result in improved H2O2 yield.更多还原