低温等离子体-催化协同降解挥发性有机废气

低温等离子体-催化协同技术适合于各类挥发性有机物的治理,特别是大气量低浓度的有机废气的处理.高效催化剂的加入可 以显著提高等离子体反应中有机废气的降解效率,减少有害副产物的生成以及提高反应器的能量利用率.从反应器、催化剂以及背景气体等方面探讨了该技术实现产业化需要解决的问题,结合低温等离子体与催化剂的相互作用、等离子体...     

La-Co-Fe-Cu/HZSM-5在尾气碳颗粒燃烧中的催化性能

采用柠檬酸络合低温浸渍法制备分子筛负载钙钛矿型复合氧化物催化剂。采用XRD、SEM和H2-TPR等手段对催化剂性能进行表征,并在微型固定床反应器中对催化剂进行活性评价。结果表明,在钙钛矿型复合氧化物中进行B位离子掺杂,可以改善催化活性,碳颗粒燃烧温度降低。在20%LaCoO3/HZSM-5催化剂中用铁离子部分取代钴离子可以改善碳颗粒的燃烧性能,取代量增加碳颗粒燃烧温度降低,但是生成CO2的选择性也降低,以20%LaCo0.2Fe0.8O3/HZSM-5为催化剂,Tig、Tm和Tf分别为256℃、399℃和403℃,但生成CO2的选择性只有72.5%。在20%LaCo1-xFexO3/HZSM-5中的钙钛矿型复合氧化物B位离子中加入铜离子后,在碳颗粒燃烧反应中生成CO2的选择性得到明显改善,Sco2提高10个单位以上。以20%LaCo0.2Fe0.6Cu0.2O3/HZSM-5为催化剂,在碳颗粒燃烧反应中生成CO2的选择性可以达到94.7%,Tig、Tm和Tf分别为242℃、427℃和445℃。     

燃煤电厂烟气氮氧化物排放控制技术发展现状

在广泛查阅文献的基础上,对近年来国内外已成功应用和正在研究开发的一些主要的燃煤烟气氮氧化物控制技术进行了介绍。结合我国目前脱硝行业整体水平和国家环保政策要求,对我国脱硝行业技术研发方向提出了建议。     

餐饮废油均相法制取生物柴油研究进展

阐述了餐饮废油(WCO)制备生物柴油的均相催化方法,介绍了餐饮废油生物柴油的特性和排放性能,并展望了生物柴油生产的发展趋势.     

河南仰韶生化做推动产业发展的“催化酶”

生物产业是一个对人类健康、粮食、生态环境、可持续发展产生重大影响的战略性新兴产业。     

催化还原法净化处理氮氧化物的工程实例

针对不锈钢产品酸洗处理过程中产生的氮氧化物浓度高、对大气污染的影响大、且难于净化治理等特性,在上海某不锈钢项目中设计了一套酸雾净化系统。该设计解决了酸洗中产生的氮氧化物难以净化的问题,提升了氮氧化物处理技术,它将成为不锈钢酸洗行业中氮氧化物净化处理技术的发展方向。     

Catalytic bubble-free hydrogenation reduction of azo dye by porous membranes loaded with palladium nanoparticles

Catalytic bubble-free hydrogenation reduction of azo dye by porous membranes loaded with palladium （Pd） nanoparticles was studied for the first time. The effects of Pd loading, dye concentration and reuse repetitions of membranes were investigated. In reduction, the dye concentration decreased whereas the pH rose gradually. An optimal Pd loading was found. The catalytic membranes were able to be reused more than 3 times.     

Reaction mechanism and metal ion transformation in photocatalytic ozonation of phenol and oxalic acid with Ag+/TiO2

Photocatalytic ozonation of phenol and oxalic acid （OA） was conducted with a Ag^＋/TiO2 catalyst and different pathways were found for the degradation of different compounds. Ag^＋ greatly promoted the photocatalytic degradation of contaminants due to its role as an electron scavenger. It also accelerated the removal rate of OA in ozonation and the simultaneous process for its complex reaction with oxalate. Phenol could be degraded both in direct ozonation and photolysis, but the TOC removal rates were much higher in the simultaneous processes due to the oxidation of hydroxyl radicals resulting from synergetic effects. The sequence of photo-illumination and ozone exposure in the combined process showed quite different effects in phenol degradation and TOC removal. The synergetic effects in different combined processes were found to be highly related to the properties of the target pollutants. The color change of the solution and TEM result confirmed that Ag＋ was easily reduced and deposited on the surface of Tit2 under photo-illumination, and dissolved again into solution in the presence of ozone. This simple cycle of enrichment and distribution of Ag^＋ can greatly benefit the design of advanced oxidation processes, in which the sequences of ozone and photo-illumination can be varied according to the needs for catalyst recycling and the different properties of pollutants.     

Effects of metal and acidic sites on the reaction by-products of butyl acetate oxidation over palladium-based catalysts

Catalytic oxidation is widely used in pollution control technology to remove volatile organic compounds. In this study, Pd/ZSM-5 catalysts with different Pd contents and acidic sites were prepared via the impregnation method. All the catalysts were characterized by means of N2 adsorption- desorption, X-ray fluorescence （XRF）, HE temperature programmed reduction （H2-TPR）, and NH3 temperature programmed desorption （NH3-TPD）. Their catalytic performance was investigated in the oxidation of butyl acetate experiments. The by-products of the reaction were collected in thermal desorption tubes and identified by gas chromatography/mass spectrometry. It was found that the increase of Pd content slightly changed the catalytic activity of butyl acetate oxidation according to the yield of CO2 achieved at 90%, but decreased the cracking by-products, whereas the enhancement of strong acidity over Pd-based catalysts enriched the by-product species. The butyl acetate oxidation process involves a series of reaction steps including protolysis, dehydrogenation, dehydration, cracking, and isomerization. Generally, butyl acetate was cracked to acetic acid and 2- methylpropene and the latter was an intermediate of the other by-products, and the oxidation routes of typical by-products were proposed. Trace amounts of 3-methylpentane, hexane, 2-methylpentane, pentane, and 2-methylbutane originated from iso4merization and protolysis reactions.     

Mo-modified Pd/Al2O3 catalysts for benzene catalytic combustion

Mo-modified Pd/Al2O3catalysts were prepared by an impregnation method and tested for the catalytic combustion of benzene. The catalysts were characterized by N2 isothermal adsorption, X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, temperatureprogrammed desorption of NH3（NH3-TPD）, H2temperature-programmed reduction（H2-TPR）, and high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM）. The results showed that the addition of Mo effectively improved the activity and stability of the Pd/Al2O3catalyst by increasing the dispersion of Pd active components, changing the partial oxidation state of palladium and increasing the oxygen species concentration on the surface of catalyst. In the case of the Pd-Mo/Al2O3catalyst,benzene conversion of 90% was obtained at temperatures as low as 190°C, which was 45°C lower than that for similar performance with the Pd/Al2O3catalyst. Moreover, the 1.0% Pd-5% Mo/Al2O3catalyst was more active than the 2.0% Pd/Al2O3catalyst. It was concluded that Pd and Mo have a synergistic effect in benzene catalytic combustion.