低温等离子体-催化耦合降解甲苯的研究及机理探讨

目前对挥发性有机化合物VOCs废气的等离子体联合处理技术的研究已成为国内外研究的热点,但在等离子体联合技术降解VOCs的反应过程中会产生臭氧、NOx及其他卤化物等二次污染物,且对VOCs降解反应过程缺乏较为深入的理论分析及相应的动力学模型研究.为了实现低能耗去除污染物,并使反应具有选择性,本研究采用了自制的复合型催化剂...     

On Vehicle VOC and NOx Emissions from the Standpoint of the Tropospheric Ozone Problem

Ozone is formed in and downwind of urban areas from urban emissions of NO_x and volatile organic compounds (VOCs) in the presence of sunlight. The main sources of VOCs in polluted air are motor vehicles, industrial solvents, processes in the petroleum and chemical industries, and vegetation. The main NO_x sources are stationary-source fuel combustion (mainly electric utilities) and motor vehicles. Recent studies have demonstrated that VOC emissions from motor vehicles have been seriously underestimated, and this may well explain why ambient O₃ has not responded well to control efforts. This review presents an overview of the sources, formation, and potential abatement strategies for O₃ pollution in the troposphere, with particular emphasis on the mobile source contribution to O₃ formation.     

Ozone Measurements at Some Work Places for Environment Protection and Career Health Care

Air pollution has become one of the top issues in China. The Chinese government has launched a national program to reduce emissions of particulate matter (PM2.5), carbon dioxide, sulfur dioxide and nitrogen oxide during its “Twelfth Five-Year Plan” (2011–2015). In the following decade (2016–2025) emphases will be placed on control of volatile organic compounds (VOCs) emissions and ground-level ozone. Before that, a lot of background knowledge has to be known such as source apportionments of VOCs and ozone in air environment, which is so far very limited in China. In this work, concentrations of ozone and its precursors were measured at work places like petroleum factory, coal-fired power plant, shipbuilding factory (welding site) and heavy traffic road. The major aim of this article is to investigate the presence of those point sources in ozone formation in the area. Although the measurements were rough, results met the needs of China’s strategy on environment protection and career health care, and may serve as reference data for basic research work.     

Volatile-Mediated Interactions between Cabbage Plants in the Field and the Impact of Ozone Pollution

Plants constitutively release volatile organic compounds (VOCs), but qualitatively and quantitatively alter their emission of VOCs in response to biotic and abiotic stresses. The blend of VOCs emitted reflects the physiological status of the plant. Plants may be exposed to the VOC blend emitted by their near neighbors and gain information that allows them to adjust their own defenses. These plant-plant interactions may potentially be exploited to protect crops from pests, but they can be disturbed by abiotic factors making the process sensitive to environmental perturbation. Despite numerous studies describing plant-plant interactions, relatively few have been conducted with agriculturally significant cultivated plant varieties under field conditions. Here we studied plant-plant interactions in a conspecific association of Brassica oleracea var. capitata (cabbage) and show that undamaged plants exposed to neighbors damaged by the herbivore Pieris brassicae are primed for stronger volatile emissions upon subsequent herbivore attack. We conducted a field study in an ozone free-air concentration enrichment (FACE) facility with ambient and elevated ozone levels and found that elevated tropospheric ozone significantly alters the priming of VOCs in receiver plants. We conclude that plant-plant interactions may prime defensive attributes of receiver plants under field conditions, but are impaired by ozone pollution. Therefore, when planning the manipulation of plant-plant interactions for agricultural purposes, the potential effects of atmospheric pollutants should be considered.     

燃煤有机污染物排放及其控制技术研究展望

有机污染物排放是导致大气复合型污染、诱发雾霾、产生光化学烟雾的重要诱因,是当前研究的热点问题。燃煤是有机污染物的来源之一。本文综述了燃煤有机污染物的排放特性,包括燃煤有机物的排放浓度及主要组分,影响燃煤有机物生成的因素,指出燃煤有机污染物浓度较低,苯系物是其重要组成之一。分析了烟气系统中有机物的迁移转化以及烟气处理设施（选择性催化还原脱硝、湿法脱硫、电除尘、湿式电除尘、低低温电除尘）的协同去除作用。最后基于吸附技术和催化技术的研究现状,展望了未来燃煤有机污染物控制的研究方向为：结合现有设备的协同去除作用,优化工艺条件,开发适合燃煤有机物的高效吸附剂和催化剂,开发集高效吸附/氧化/烟气协同净化技术于一体的燃煤有机物高效控制技术。     

工业源挥发性有机物排放特征及控制对策探讨——以广东省Z市为例

大气污染是比较突出的环境污染问题,其中挥发性有机物(VOCs)的排放对人类健康产生威胁。随着产业转移,Z市工业源VOCs逐年增加,大气环境问题日益突出。通过实地调研和收集资料,并结合VOCs排放清单研究,分析了Z市VOCs排放特征。研究发现,Z市VOCs主要来源于工艺过程源和溶剂使用源(36.85%)、移动源(31.32%)、非工业溶剂使用源(15.74%)和生物质燃烧源(10.24%)的排放,主要涉及的行业包括:化学原料和化学品制造业、食品制造业、橡胶和塑料制品业、纺织业、非金属矿物制品业等。结合Z市的VOCs排放特征,针对性地提出了工业源VOCs污染控制对策,也希望通过此次对VOCs排放控制的研究,为解决实际问题起到一定启示作用。     

红外掩日通量遥感监测技术在石化VOCs排放监测中的应用

石化企业主要以无组织形式排放烷烃、烯烃、芳烃等挥发性有机物(VOCs),不仅污染大气,也引起加工损失。为有效控制和减少石化VOCs排放,有必要监测石化企业VOCs排放总量及分布。红外掩日通量遥感监测技术(SOF)是当前VOCs无组织排放通量监测最佳实用技术之一,简要介绍了其技术原理、测量方法、应用范围及在石化VOCs排放监控中的应用。     

Bioprocesses for the removal of nitrogen oxides from polluted air

Nitrogen oxides (NOx) of environmental concern are nitrogen monoxide (NO) and nitrogen dioxide (NO₂). They are hazardous air pollutants that lead to the formation of acid rain and tropospheric ozone. Both pollutants are usually present simultaneously and are, therefore, called NOx. Another compound is N₂O which is found in the stratosphere where it plays a role in the greenhouse effect. Concern for environmental and health issues coupled with stringent NOx emission standards generates a need for the development of efficient low‐cost NOx abatement technologies. Under such circumstances, it becomes mandatory for each NOx‐emitting industry or facility to opt for proper NOx control measures. Several techniques are available to control NOx emissions: selective catalytic reduction (SCR), selective non‐catalytic reduction (SNCR), adsorption, scrubbing, and biological methods. Each process offers specific advantages and limitations. Since bioprocesses present many advantages over conventional technologies for flue gas cleaning, a lot of interest has recently been shown for these processes. This article reviews the major characteristics of conventional non‐biological technologies and recent advances in the biological removal of NOx from flue gases based on the catalytic activity of either eucaryotes or procaryotes, ie nitrification, denitrification, the use of microalgae, and a combined physicochemical and biological process (BioDeNOx). Relatively uncomplicated design and simple operation and maintenance requirements make biological removal a good option for the control of NOx emissions in stationary sources. Copyright © 2005 Society of Chemical Industry     

Room temperature oxidation of acetone by ozone over alumina-supported manganese and cobalt mixed oxides

Volatile organic compounds (VOCs) are among the major sources of air pollution. Catalytic ozonation is an efficient process for removing VOCs at lower reaction temperature compared to catalytic oxidation. In this study, a series of alumina supported single and mixed manganese and cobalt oxides catalysts were used for ozonation of acetone at room temperature. The influence of augmenting the single Mn and Co catalysts were investigated on the performance and structure of the catalyst. The manganese and cobalt single and mixed oxides catalysts of the formula Mn10%-CoX and Co10%-MnX (where X= 0, 2.5%, 5%, or 10%) were prepared. It was found that addition of Mn and Co at lower loading levels (2.5% or 5%) to single metal oxide catalysts enhanced the catalytic activity. The mixed oxides catalysts of (Mn10%-Co2.5%) and (Mn10%-Co5%) led to acetone conversion of about 84%. It is concluded that lower oxidation state of the secondary metal improves ozone decomposition and oxidation of acetone.     

石化中间储罐挥发性有机物排放特征与反应活性

中间储罐是石化企业的主要挥发性有机物(VOCs)排放源,对大气环境产生重要影响。本文对我国某石化企业炼化中间产物、污油、石化中间产物等中间储罐大呼吸过程进行了采样监测,分析了VOCs排放特征并建立了有机污染物图谱。基于OH自由基损失速率和最大增量反应活性法,分别量化了大呼吸过程大气反应活性和臭氧生成潜势(OFP)。结果表明,中间储罐大呼吸过程VOCs浓度高达数万毫克每立方米,单位体积物料周转量VOCs排放强度达到0.55～71.3g/m³。不同储罐排放特征差异大,炼化中间产物及污油储罐VOCs组成以烷烃为主,石化中间产物储罐VOCs以烯烃和芳香烃为主;C₃～C₇烷烃、C₃～C₄烯烃、苯、甲苯和丙酮等是首要污染物。中间储罐大呼吸损耗气具有较高大气光化学反应活性和臭氧生成潜势(OFP),OH自由基损失速率常数接近1.43×10⁴～2.37×10⁶s^-1,OFP达到2.84×10⁵～7.53×10...     

Activated carbon cloth adsorption-cryogenic system to recover toxic volatile organic compounds

There is an emergent need to reduce the emissions of toxic volatile organic compounds (VOCs) to the atmosphere. One strategy to reduce the emissions of VOCs from point sources is to use air pollution control devices on the sources' discharge streams. This paper describes the development of a new activated carbon cloth (ACC) adsorption system that is integrated with cryogenic vapor recovery to reduce the amount of VOCs emitted to the atmosphere from point sources and provide for reuse of the VOCs that are recovered. Electrical current is used to regenerate the ACC. ACC adsorption followed by electrothermal regeneration results in formation of a concentrated organic vapor which is cryogenically condensed from the gas phase. Electrothermal desorption allows for careful control of the desorption time and the concentration profile of the desorbed VOC to allow minimal use of cryogen. Adsorption, followed by cryogenic treatment enables VOC sources to meet air quality control regulations while providing a high quality liquid VOC product for reuse.     

三聚磷酸盐聚合尾气的脱硝工艺

NOx是大气主要污染物之一,也是目前大气污染治理的一大难题。磷化工生产过程中同样会产生NOx,但并没有引起人们的足够重视。介绍几种主要的脱硝技术:选择性催化还原脱硝、选择性非催化还原脱硝、臭氧分解、直接吸附等,为磷酸盐聚合尾气脱硝提供技术参考。同时介绍了兴发集团拟采用的三聚磷酸钠聚合尾气脱硝技术。     

A modeling study of the impact of natural and urban forest on ambient ozone

Impact estimation of biogenic VOCs (Volatile Organic Compounds) to control ambient ozone is needed. For this, BVOCs emission is calculated by using BEIS, and the impact of ozone is estimated with UAM in the research area, Daegu metropolitan city. It is estimated that 59 ppb and 50 ppb of ozone concentration is caused by BVOCs emissions and anthropogenic emissions, respectively. As for tree type, deciduous trees have greater influence than conifers on the daily maximum 1-hr ozone concentration though the former’s distribution area is smaller than the latter’s. In addition, variation of ozone concentration by BVOCs emission is more sensitive in city areas compared to rural areas. If we change the landscape from woody plants (urban trees) to lower ozone-forming potential (OFP) species, it should lead to a reduction in grids that exceed the national ambient ozone standard.     

旋转填料床中硝酸吸收NO_x的实验研究(英文)

Absorption of NOx into nitric acid solutions was studied in the presence of ozone by using a rotating packed bed (RPB) contactor. The influences of operating parameters, such as high gravity number, amount of ozone, gas velocity, liquid spray density and inlet concentration of NOx, on the removal efficiency of NOx were investigated, among which the high gravity number and ozone amount are more important. Ozone was introduced to oxidize HNO2 to HNO3 to prevent the decomposition of HNO2 in the liquid phase. The high gravity number presents the effective external force for enhancing the mass transfer of ozone from gas phase to liquid phase. Under the experimental condition, the removal efficiency of NOx is higher than 90% and the concentration of nitric acid product exceeds 45%.     

Formation and Lifetime of Polycyclic Aromatic Compounds During a National-Scale Transient Pollution Episode

Concentrations of selected particle-borne parent, alkylated, oxygenated, and nitrated polycyclic aromatic compounds (PACs) have been monitored before, during, and after a large national-scale wood-burning pollution episode (5 November 1994 and 4-5 November 1995). Toluene-modified supercritical CO 2 was used for the extraction of PACs from the collected particulate matter. Analysis was performed using an on-line multidimensional chromatographic technique using coupled liquid and gas chromatography (LC-GC) with loop interface. Comparison of average urban and wood smoke particulate PAC profiles identified a marked change in the ambient PAC profile for the pollution episode period, caused by the change in emission source from predominantly vehicular to wood smoke. A chemical mass balance model has been used to calculate the relative contributions from general urban and wood smoke PAC sources and from them, an estimation of the atmospheric life-time of the PAC emissions has been made. When monitored with 24 hr resolution in 1994, the concentrations of quinone-PAC oxidation products were found to peak 1 day after the maximum concentrations in the parent PAH were recorded, consistent with photochemically driven reactions with singlet state molecular oxygen. When concentrations were monitored on a more frequent basis in 1995, the concentrations of oxygenated species were seen to begin increasing in concentration before sunrise but still peaking after the maximum concentrations of parent PAH were recorded. The nighttime rise in product PAC suggests dark reactions with ozone or the NO 3 radical also may be occurring.     

Indoor air quality and the emissions of VOCs from interior products

Indoor air quality (IAQ) has developed into an important environmental and health concern. IAQ legislation has been introduced in the U.S. Congress. Volatile organic compounds (VOCs) comprise a part of the total concern about IAQ. Types and sources of pollutants contributing to IAQ are identified. Some strategies for reducing VOCs in indoor air are provided, and various sources of VOCs are identified. Various means of reducing VOC emissions from products are presented. Government regulatory agencies have begun to introduce legislation focusing on regulation of IAQ. Discussed is how these regulations, some proposed legislation, and customer concerns will affect both product manufacturers and their suppliers.     

Hourly elemental composition and sources identification of fine and coarse PM10 particulate matter in four Italian towns

The composition of particulate matter in the atmosphere of four major italian towns (Florence, Genoa, Milan and Naples) has been studied with hourly resolution by means of ion beam analysis (IBA) techniques and statistical methods. The aerosol has been collected simultaneously in the four towns during the first weeks of year 2001, by two-stage continuous streaker samplers, which separate and collect the PM10 particulate matter in two fractions. The hourly concentrations in air of about 20 elements have been extracted in the fine and coarse fractions of PM10 by particle induced X-ray (and gamma-ray) emission, PIXE (and PIGE), analysis of about 2700 hourly samples. The coupled use of streaker samplers and IBA techniques made distinguishable time patterns typical of urban environments as well as fast and occasional episodes. Absolute principal component factor analysis (APCFA) and other statistical approaches have been used to obtain a sintetic apportionment of the sources of particulate matter.     

工业挥发性有机污染物控制与资源化利用

综述了多种不同的工业挥发性有机污染物(VOCs)控制技术,从工程应用角度分析了其适用范围、优缺点、应用现状和研究方向等。在此基础上,针对目前工业VOCs控制过程存在的低浓度大风量VOCs处理问题、复杂VOCs废气体系处理问题及单一控制方法治理效率低等问题,提出对现有工艺技术设备的优化建议、不同处理方式集成组合、源头治理等改进手段,从宏观角度探讨了VOCs资源化的社会发展需求及解决方案。     

低温等离子体除苯过程中臭氧的演变与作用

大气污染物中,挥发性有机化合物(VOCs)已超越NOx和SO_2成为排放量最高的气态污染物,对人体健康和环境的影响已引起广泛关注。相比传统去除VOCs的技术,低温等离子体法具有高效率、低能耗、易操作等优势,但有产生臭氧(O_3)等副产物的问题。本研究选择苯作为VOCs的代表污染物,采用线管式介质阻挡放电反应器,考察电压、电流等放电参数对苯去除率、副产物臭氧浓度和CO_2选择性的影响,重点分析臭氧的演变、机理及其作用。结果表明,影响臭氧浓度的直接因素是输入功率:随着输入功率的上升,苯去除率逐渐上升,臭氧浓度先上升后下降。其原因在于高功率下生成更多低能电子,使得臭氧分解为氧气。等离子体产生的臭氧无法直接氧化苯,但可以氧化苯的中间产物CO完全转化为CO_2。     

石化行业发展现状及VOCs控制技术研究

石化行业在国民经济中占有极为重要的位置,原料和产品生产、储运和使用等过程中排放出大量挥发性有机物（Volatile Organic Compounds,简称VOCs）,带来了一系列的环境污染问题。初步研究了VOCs来源及主要污染物类别,从源头控制、清洁生产工艺、末端治理技术等角度总结了VOCs污染防治措施,并提出了发展建议,为该行业的VOCs综合防治工作提供了参考依据。