H2S and NH3 Removal by Silent Discharge Plasma and Ozone Combo-System

Treatment of H₂S and NH₃ using the non-thermal plasma (NTP) methods was investigated. Two NTP systems were used in this study, one consisting of a multi-cell plate-to-wire reactor (PTW), and the other consisting of an ozonization chamber and the multi-cell PTW reactor. Each cell of the PTW reactor had a sheet of copper foil embedded in dielectric layers as its high voltage electrode and a wired rack as its gounded electrode. Use of the wired rack type electrode allowed large flow throughput, and promoted intense local electric fields. The experiments showed that under constant energy input, the decomposition efficiency of H₂S or NH₃ decreased with increasing initial concentration of the gas, and increased with increasing injected ozone and relative humidity. Injection of NH₃ into H₂S stream did not improve the H2S decomposition efficiency but was necessary for removal of sulfite-containing compounds in the discharge air.     

等离子体在同时去除NOx和碳烟催化反应中的作用

采用程序升温反应(TPR)技术,研究了等离子体辅助同时催化去除富氧柴油机尾气中NO_x和碳烟(soot)的反应特性.研究结果表明,等离子体提高了同时去除NO_x-soot的催化反应活性,降低了碳烟的燃烧温度,使碳烟起燃温度从300 ℃降到280 ℃,燃尽温度从425 ℃降到380 ℃;同时,等离子体辅助提高了NO_x转化为N₂的效率,使催化选择性从1.12％提高到1.53％.本文还分别研究了在NO和O₂的环境中,有或没有等离子体作用下,碳烟在催化作用下的去除特性.等离子体作用使得NO在和O₂共存、只有NO和只有O₂存在的各种条件下,碳烟的催化燃烧活性都有不同程度的提高,促进了N₂的生成.此外,本文也对等离子体辅助同时催化去除NO_x-soot的机理进行了探讨.     

大气及液空、液氧中氧化亚氮测定方法的研究

建立了一种用电子捕获检测器气相色谱法(GC-ECD)测定大气及空气分离装置液空、液氧中N2O的测定方法。通过选择性条件试验,确定了用GC-ECD法测定大气及空气分离装置液空、液氧中N2O含量的最佳色谱柱为不锈钢填充柱,固定相为GDX-103(0.154~0.18 mm粒径);最佳载气流速为18 mL/m in,最佳分离的柱温为30℃。方法具有较高的灵敏度,检出限为:当进样量为0.5mL时,可测准至N2O浓度0.1μL/L的气体,检出限为0.014μL/L。方法的准确度较高,以峰面积定量,其标准偏差为0.013;相对标准偏差为3.74%。     

DBD Plasma Treatment of Titanium in O2, N2 and Air

Dielectric Barrier Discharge plasma treatment of a titanium metal foil in oxygen, nitrogen and air under atmospheric conditions is investigated employing X-Ray Photoelectron Spectroscopy (XPS). We investigated three different reference samples and compare the results with a large number of studies on the XPS analysis of titanium compounds containing oxygen and nitrogen. The plasma treatment in all three different process gases leads to the formation of titanium dioxide films, while rather small nitrogen fractions are found after nitrogen and air plasma treatments. This finding is explained basing on plasma chemistry insight from the literature.     

N_2O在Mg-Fe复合氧化物上的催化分解(英文)

用共沉淀法制备了一组Mg-Fe复合氧化物催化剂,用于N2O催化分解,考察了催化剂组成、焙烧温度、负载助剂钾等参数对其催化活性的影响。采用N2物理吸附、X射线衍射、H2-程序升温还原等技术对催化剂进行了结构表征。结果表明,500℃焙烧的Mg0.6Fe0.4Fe2O4催化剂对于N2O分解反应有较高活性,而K改性的催化剂活性均有所降低,且K的负载量越高,改性催化剂的活性越低,这是由于负载的K粒子抑制了表面铁物种的还原,降低了催化剂的比表面积。在有氧无水、水氧共存条件下连续反应10h,Mg0.6Fe0.4Fe2O4的催化活性和稳定性均显著高于FeOx催化剂。     

Catalytic two-electron reductions of N2O and N3- by myoglobin in surfactant films

Myoglobin (Mb), in films of dimethyldidodecylammonium bromide (ddab) on graphite electrodes, is used as a catalyst to mediate the electrochemical reduction of nitrous oxide (N2O) as well as the isoelectronic ion azide (N3-) in aqueous solutions. The electrocatalytic reductions are characterized by a rate-dependent irreversibility in cyclic voltammograms of Mb/ddab in the presence of the substrates. Bulk electrolysis shows that the reduction of 15N15NO by Mb/ddab yields 15N15N as shown by GC/MS. The catalytic reduction of azide results in almost quantitative formation of ammonia. These electrocatalytic processes are rationalized as two-electron reductions, with the catalyst cycling between the Fe(I) and Fe(III) states of Mb. To our knowledge, this is the first characterization of N2O reduction by an Fe porphyrin or heme protein.     

钴铈复合金属氧化物催化剂上氧化亚氮催化分解性能研究

采用共沉淀法制备了一系列钴铈复合金属氧化物催化剂CoCex(x=0～0.2,x为Ce/Co摩尔比),进行了比表面积和XRD表征,并考察了它们对氧化亚氮催化分解反应的活性.结果表明,随着铈添加量的增加,催化剂上钴尖晶石相的衍射峰逐渐宽化,同时催化剂的比表面积逐渐增大;催化剂的活性随着铈添加量的增加先升高,然后下降,CoCe0.05催化剂表现出了最佳催化活性.在对CoCe0.05催化剂制备条件的考察实验中发现,共沉淀过程中控制pH值在9左右,于400 ℃焙烧得到的催化剂的活性最好.当反应气氛中存在O2或H2O时,CoCe0.05催化剂上N2O的分解反应受到抑制,但这种影响是可逆的,可能是由于它们与N2O在相同的活性位上存在竞争吸附.     

负载型La2-xSrxCuO4催化分解N2O的研究

合成了负载在莫来石上x值不同的La2-xSrxCuO4(0≤x≤1)系列复合氧化物,用XRD、SEM等方法研究了这类复合氧化物的结构和氧化还原性能,考察了对N2O分解的催化活性,并对反应的宏观动力学进行了讨论,认为对于N2O的分解是一级反应。     

Observation and Identification of an Atomic Oxygen Structure on Catalytic Gold Nanoparticles

Interactions between oxygen and gold surfaces are fundamentally important in diverse areas of science and technology. In this work, an oxygen dimer structure was observed and identified on gold nanoparticles in catalytic decomposition of hydrogen peroxide to oxygen and water. This structure, which is different from isolated atomic or molecular oxygen surface structures, was observed with in situ surface‐enhanced Raman spectroscopic measurements and identified with density functional theory calculations. The experimental measurements were performed using monodisperse 5, 50 and 400 nm gold particles supported on silica with liquid‐phase hydrogen and deuterium peroxides at multiple pH values. The calculations show that on surfaces with coordinatively unsaturated gold atoms, two oxygen atoms preferentially share a gold atom with a bond distance of 0.194–0.196 nm and additionally bind to two other surface gold atoms with a larger bond distance of 0.203–0.213 nm, forming an Au‐O‐Au‐O‐Au structure. The formation of this structure depends on reaction rates and conditions.     

N_2O分解催化剂Co-Al尖晶石型复合氧化物制备参数的优化

以柠檬酸为配合剂,用溶胶-凝胶法制备了一组不同组成的Co-Al复合氧化物(CoAl_2O_4、CoCo0.5Al1.5O4、CoCoAlO_4、CoCo_(1.5)Al_(0.5)O_4、Co_3O_4),用于催化分解N_2O.用N_2物理吸附、X射线衍射(XRD)、扫描电镜(SEM)、H2程序升温还原(H2-TPR)、X射线光电子能谱(XPS)等技术对催化剂进行了结构表征,考察了复合氧化物组成、母液pH值、配合剂用量等制备参数对催化剂活性的影响.结果表明:用Al取代Co_3O_4中部分Co制备Co-Al复合氧化物,提高了催化剂的比表面积和催化活性,其中组成为CoCo_(1.5)Al_(0.5)O_4、母液pH=2、柠檬酸/金属离子(摩尔比)为1的催化剂活性较高.在CoCo_(1.5)Al_(0.5)O_4表面浸渍K2CO3溶液制得K改性催化剂,弱化了钴-氧化学键,提高了催化活性.其中0.02K/CoCo1.5Al0.5O4催化剂在有氧有水气氛400℃连续反应50h,N_2O转化率达97.1%.     

Role of surface defects in activation of O2 and N2O on ZrO2 and yttrium-stabilized ZrO2

The relationship between the structure of both yttrium-stabilized zirconia (YSZ) and ZrO2 catalysts and their ability to activate N2O and O2 is studied by determination of catalytic properties and characterization with TPD, SEM, and XRD. Furthermore, the role of oxygen species formed via dissociation of either O2 or N2O in catalytic partial oxidation of methane (CPOM) is determined. N2O can be activated at both structural defects (e.g., Zr cations located at corners) and intrinsic oxygen vacancies (Zr'(Zr)-V(O)**Zr'(Zr)) and forms two types of oxygen species (alpha-O and beta-O) on the surface, respectively. In contrast, molecular oxygen gives rise to only one type of oxygen species (beta-O), that is, surface lattice oxygen. This type of oxygen species can be extracted by reaction with methane, forming the intrinsic oxygen vacancies again during CPOM. However, the structural defects are not active for oxygen activation during CPOM. Doping ZrO2 with Y2O3 significantly decreases the number of structural defects via replacement of Zr4+ cations by Y3+ cations, located at corners, steps, kinks, and edges of the crystallites. Calcination at higher temperatures results in less structural defects due to both increasing crystallite size as well as transformation to more regular shaped crystallites. High temperature calcinations also increase the activity of YSZ in CPOM. This is attributed to the increase in the exposition of low index planes, especially those (111) with the lowest surface energy and the highest coordination numbers, induced by the thermal treatment.     

Effects of Oxygen (O2) Plasma Treatment in Promoting the Germination and Growth of Chili

In general, seed germination is improved by low-pressure plasma treatment using precursors such as air, nitrogen, O_2, and argon, etc. For the first time, low-pressure O₂ plasma was used to treat chili seeds in this study. When compared to untreated and vacuum-treated seeds, O₂ plasma treatment using the discharge power of 80 W for 60 s significantly improves chili seed germination and growth. The effect of vacuum on the germination and growth of chili seeds was also studied and shown to be negligible. The physical and chemical changes induced by O₂ plasma treatment were investigated to understand the plasma treatment to germination improvement. Combinatory etching and chemical modification aided imbibition and increased germination percentage in this O₂ plasma treatment on chili seeds. The success of this method has the potential to be scaled up to solve food security issues with seeds that would otherwise struggle to germinate.

     

Plasma Assisted Catalytic Conversion of CO2 and H2O Over Ni/Al2O3 in a DBD Reactor

Plasma Chemistry and Plasma Processing - We present an innovative approach for reacting carbon dioxide and water to give syngas by combining heterogeneous catalysis and non-thermal plasma...     

N_2O在Cu_xFe_(1-x)Fe_2O_4和Ni_xFe_(1-x)Fe_2O_4复合氧化物催化剂上的分解反应

用共沉淀法制备了一组具有尖晶石结构的Cu-Fe和Ni-Fe复合氧化物,用于有氧条件下催化分解N2O,考察了催化剂组成对催化活性的影响.用N2物理吸附(BET)、X射线衍射(XRD)、H2程序升温还原(H2-TPR)等技术对催化剂进行了结构表征.结果表明:在不同组成的Cu-Fe、Ni-Fe系列复合氧化物催化剂中,Cu Fe2O4和Ni Fe2O4对于N2O分解反应的初活性较高,这是因为Cu Fe2O4和Ni Fe2O4的比表面积较高、晶粒较小,而且其表面氧物种与金属(Cu2+、Fe3+)的化学作用较弱,氧物种易脱除、脱氧量较高.相比较而言,Ni Fe2O4催化剂上的N2O分解活化能低于Cu Fe2O4,Ni Fe2O4的初活性优于Cu Fe2O4.500℃连续反应100 h,Cu Fe2O4上的N2O转化率降至84.9%,而Ni Fe2O4上的N2O转化率一直保持99%,Ni Fe2O4有较高的催化稳定性.     

Removal of Hexanal by Non-thermal Plasma and MnOx/y-Al2O3 Combination

研究了在低温等离子体和催化剂共同作用下低浓度正己醛的降解反应.结果表明,等离子体与γ-Al2O3之间产生了很好的催化协同作用,在低放电功率(2.8W)和低温(80 ℃)下,干燥空气气氛中,γ-Al2O3对0.12％正己醛的去除率为87.1％;当γ-Al2O3负载7.5％MnOx后,正己醛去除率达到96.5％,其效果与Pt/γ-Al2O3相当.7.5％MnOx/γ-Al2O3在实验条件下连续使用50h,其催化活性未见下降.     

泡沫铝负载钌基催化剂应用于N2O的低温催化分解研究

将导热性能良好的泡沫铝作为载体,羰基钌为前驱体制备了一系列不同形态的钌基催化剂应用于N2O的低温催化分解研究.采用XRD、XPS、SEM、TEM、BET、H2-TPR等方法对催化剂进行了表征,于石英管固定床反应器上对催化剂性能进行了评价.重点考察了泡沫铝作为催化剂载体的可行性、载体的处理方法对催化剂活性的影响以及RuO2、Ru、Ru3(CO)12所表现出的活性差异.结果表明:泡沫铝作为催化剂载体,能够促进N2O的催化分解;泡沫铝经H2O2处理有利于提高其对活性中心的附着力,提高催化活性;N2O浓度为1%,Ru负载量为0.3%,活性中心分别为Ru3(CO)12、Ru、RuO2时,N2O完全转化温度依次为285、380和415℃;活性较高的Ru3(CO)12/泡沫铝催化剂在长时间作用后活性组分转变为RuO2.     

N2O在Au/Co3O4和Au/ZnCo2O4催化剂上的分解反应

通过调变HAuCl₄溶液的pH值和Au负载量,用沉积-沉淀法制备了一系列Au/Co₃O₄催化剂,并采用AES、BET、XRD、SEM、XPS和H₂-TPR等技术对催化剂的结构和组成进行了表征,考察了制备条件对其在有氧气氛中催化N₂O分解反应性能的影响规律,得到了催化剂最佳制备条件:HAuCl₄溶液pH值为9,Au负载量为0.29%。催化测试结果表明:虽然ZnCo₂O₄的催化活性优于Co₃O₄,但0.31%Au/ZnCo₂O₄的活性和稳定性低于0.29%Au/Co₃O₄。500℃、在含氧气氛中连续反应10 h, 两者均可完全分解N₂O,但在含氧、含水气氛中0.29%Au/Co₃O₄和0.31%Au/ZnCo₂O₄上的N₂O转化率分别为92%和63%。究其原因,发现Au/Co₃O₄中Au和Co组分间存在协同效应,而Au/ZnCo₂O₄中Au和Co组分间则没有协同效应。     

The Role of Oxygen Dissociation in Plasma Enhanced Chemical Vapor Deposition of Zinc Oxide from Oxygen and Diethyl Zinc

The influence of electron impact dissociation of oxygen on neutral chemistry was studied for plasma-enhanced chemical vapor deposition (PECVD) of zinc oxide using oxygen and diethyl zinc. Electron conditions in the reactor were estimated based on simulations of well-known Ar-O₂ plasmas, while the majority of the thermal chemistry was abstracted from the combustion literature. A rudimentary model of film growth was developed using the rate of oxygen dissociation as the lone adjustable parameter.n Model results were compared directly with experimental measurements of deposition rates and neutral species densities for a wide range of conditions. Good quantitative agreement between experiments and model were observed as a function of composition and rf power. The system is highly sensitive to the electron impact dissociation of oxygen, which creates the radical pool that drives the majority of the chemistry. The approach detailed here provides a framework for the development of models of oxide PECVD derived from other metalorganic precursors.