Simultaneous catalytic removal of NOx and diesel PM over La0.9 K0.1 CoO3 catalyst assisted by plasma

The simultaneous removal of NOx and particulate matter(PM) from diesel exhaust is investigated over a mixed metal oxide catalyst of La0.9 K0.1 CoO3 loaded on γ-Al2O3 spherules with the assistant of plasma. It was found that NOx was reduced by PM in oxygen rich atmosphere, the CO2 and N2 were produced in the same temperature window without considering the N2 formed by plasma decomposition. As a result, the temperature for the PM combustion decreases and the reduction efficiency of NOx to N2 increases during the plasma process, which indicated that the activity of the catalyst can be improved by plasma. The NOx is decomposed by plasma at both low temperature and high temperature. Therefore, the whole efficiency of NOx conversion is enhanced.     

应用低温等离子体技术治理空气污染研究进展

低温等离子体技术在治理空气污染方面以其效率高、能耗低、适用范围广等特点而成为研究热点。本文介绍了低温等离子体的概念及分类，概述了国内外利用单一低温等离子体技术及其与吸附、催化协同、多性能颗粒混合物结合治理空气污染的最新进展，指出了存在的问题并讨论了今后的研究方向和应用前景。     

微波诱导NiO催化降解水中邻苯二甲酸二甲酯

采用超声辐射沉淀-氧化法制备了纳米催化剂NiO,用XRD、XPS、BET和SEM等方法对其进行了表征.构建了微波-NiO催化反应体系,考察了该体系对DMP的去除效率及影响因素,并利用GC/MS、LC/MS鉴定降解产物,提出了可能的降解机理.结果表明：微波诱导NiO催化氧化技术是降解DMP的有效方法,在微波（750W）诱导NiO（0.4mg/L）催化降解体系中,15min内10mg/L DMP的去除率达70%以上.降解效率受到反应体系中不同条件的影响：微波功率的增加可以提高降解效率;催化剂NiO浓度越高,降解速率越快;溶液初始pH值对DMP的降解效率影响非常大,随着pH值的增大,降解效率明显提高.通过GC/MS、LC/MS分析,反应过程中DMP的降解产物主要包括双链水解产物邻苯二甲酸以及异构化产物对苯二甲酸、单链水解产物邻甲酯苯甲酸、苯环三取代产物甲酯基-邻苯二甲酸、侧链缩合形成的双环产物和少量小分子有机酸,由此推断DMP在微波诱导NiO催化体系中的降解主要包括6个途径：水解、异构化、甲酯基反应、侧链缩合成环、羟基化和开环等.     

Production of ammonia from plasma-catalytic decomposition of urea: Effects of carrier gas composition

Effects of carrier gas composition(N_2/air) on NH_3 production, energy efficiency regarding NH_3 production and byproducts formation from plasma-catalytic decomposition of urea were systematically investigated using an Al_2 O_3-packed dielectric barrier discharge(DBD) reactor at room temperature. Results show that the presence of O_2 in the carrier gas accelerates the conversion of urea but leads to less generation of NH_3. The final yield of NH_3 in the gas phase decreased from 70.5%, 78.7%, 66.6% and 67.2% to 54.1%, 51.7%, 49.6% and 53.4% for applied voltages of 17, 19, 21 and 23 kV, respectively when air was used as the carrier gas instead of N_2.From the viewpoint of energy savings, however, air carrier gas is better than N_2 due to reduced energy consumption and increased energy efficiency for decomposition of a fixed amount of urea. Carrier gas composition has little influence on the major decomposition pathways of urea under the synergetic effects of plasma and Al_2 O_3 catalyst to give NH_3 and CO_2 as the main products. Compared to a small amount of N_2 O formed with N_2 as the carrier gas, however,more byproducts including N_2O and NO_2 in the gas phase and NH_4 NO_3 in solid deposits were produced with air as the carrier gas, probably due to the unproductive consumption of NH_3, the possible intermediate HNCO and even urea by the abundant active oxygen species and nitrogen oxides generated in air-DBD plasma.     

纳米二氧化钛制备与表征

通过水热反应法合成出了两种纳米二氧化钛粉体材料,通过差热分析、X衍射分析、扫描电镜分析,粉体的平均直径小于100nm,通过光催化试验分析,纳米二氧化钛的光催化性能可以达到47%.     

Ex-ante environmental assessments of novel technologies - Improved caprolactam catalysis and hydrogen storage

Utrecht University has conducted a pilot sustainability assessment for the executive board of the chemistry program ACTS (Advanced Chemical Technologies for Sustainability) of the Netherlands’ Organization for Scientific Research (NWO). These assessments represent prospective, i.e. ’ex-ante’ studies on the production of caprolactam by an improved catalyst and on different hydrogen storage options (i.e. compressed and liquefied hydrogen, storage in metal hydrides and storage in a metal organic framework). The pilot sustainability assessments followed the principles of environmental life cycle assessment (LCA), thereby focusing on non-renewable energy use (NREU) and climate change (GWP100). It was found that caprolactam with the novel catalyst has lower impacts than petrochemical caprolactam production from benzene but higher impacts than bio-based caprolactam produced via fermentation. Regarding hydrogen storage, it was found that compressed and liquid hydrogen have the highest impacts. The impacts of the metal hydrides and the metal organic frameworks show by far the lowest environmental impacts. The main reason is that these materials can be reused up to 1500 times (refilling of tank), while for compressing and liquefaction of hydrogen energy is needed each time a tank needs to be refilled. The study demonstrates the successful application of ex-ante technology assessment.     

有机废水的电催化法降解研究现状

阐释了有机废水电催化法降解机理;综述了传统二维电极、新型三维电极电催化降解有机废水的原理及其应用现状,PbO2电极在三维电极处理有机废水中的应用现状、反应机理以及改性PbO2电极的研究进展;最后对未来发展方向进行了展望。     

硅胶催化光度法测定空气中微量NO2

为测定空气中的微量NO2,提出一种新方法,即硅胶催化光度法.显色剂为对氨基苯磺酰胺和N-(1-萘基)-乙二胺盐酸盐,将其在硅胶颗粒介质中与NO2反应,生成玫瑰红色偶氮染料.在波长540 nm下,测定其吸光度,从而计算NO2含量.将该方法与标准方法-Saltzman法进行对比.结果表明,在硅胶的催化作用下,显色反应的时间由Saltzman法的15 min降至8 min,分析测定的灵敏度也有所提高.该法操作简单方便,无干扰,用于测定空气样品中的微量NO2,结果较为满意.     

基于DSP的PPT试验样机点火安全控制系统设计

脉冲等离子体推力器PPT(Pulsed Plasma Thruster)点火安全控制系统是PPT设计中的关键.为方便灵活地控制点火脉冲和工作频率,同时保证安全点火,采用直接有脉宽调制信号PWM(Pulse width Modulalion)输出口的数字信号处理器DSP(Digital Signal Processing)控制PPT的点火,完成了DSP辅助电路、和上位机通讯的串口电路、与PPT高压触发模块(脉冲功率装置)的接口电路以及PPT点火时序控制软件的设计.PPT工作时,点火安全控制系统接收由上位机卫星喷气姿态控制算法产生的点火时刻和点火次数命令,执行点火命令.试验表明,PPT点火安全控制系统能够控制PPT试验样机,使其准确按照时序在频率0～1.67Hz(波形分辨率最高为6.67ns)下可靠点火.     

Characteristics of gas-liquid pulsed discharge plasma reactor and dye decoloration efficiency

The pulsed high-voltage discharge is a new advanced oxidation technology for water treatment. Methyl Orange (MO) dye wastewater was chosen as the target object. Some investigations were conducted on MO decoloration including the discharge characteristics of the multi-needle reactor, parameter optimization, and the degradation mechanism. The following results were obtained. The color group of the azo dye MO was effectively decomposed by water surface plasma. The decoloration rate was promoted with the increase of treatment time, peak voltage, and pulse frequency. When the initial conductivity was 1700 μS/cm, the decoloration rate was the highest. The optimum distance between the needle electrodes and the water surface was 1 mm, the distance between the grounding electrode and the water surface was 28 mm, and the number of needle electrodes and spacing between needles were 24 and 7.5 mm, respectively. The decoloration rate of MO was affected by the gas in the reactor and varied in the order oxygen > air> argon > nitrogen, and the energy yield obtained in this investigation was 0.45 g/kWh.