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11.
Based on density functional theory (DFT) and basic structure models, the chemical reactions on the surface of vanadium-titanium based selective catalytic reduction (SCR) denitrification catalysts were summarized. Reasonable structural models (non-periodic and periodic structural models) are the basis of density functional calculations. A periodic structure model was more appropriate to represent the catalyst surface, and its theoretical calculation results were more comparable with the experimental results than a non-periodic model. It is generally believed that the SCR mechanism where NH3 and NO react to produce N2 and H2O follows an Eley-Rideal type mechanism. NH2NO was found to be an important intermediate in the SCR reaction, with multiple production routes. Simultaneously, the effects of H2O, SO2 and metal on SCR catalysts were also summarized. 相似文献
12.
In order to reduce the pollutant emission and alleviate the pressure of petroleum resources shortage and greenhouse gas emission at the same time, the use of clean and renewable alternative fuel for marine engines is a promising option. In this study, a marine diesel engine, which was modified to run in diesel methanol compound combustion (DMCC) mode, was investigated. After the diesel injection parameters were calibrated, and combined with a sample after-treatment device DOC (diesel oxidation catalyst), the engine could meet the requirements of China II legislation. The overall MSP (methanol substitute percent) reached 54.1%. The value of each pollutant emission was much lower than that in China II emission legislation, and there was almost no methanol and formaldehyde emissions. When methanol was injected into the inlet manifold, the intake air temperature decreased a lot, as well as the exhaust gas temperature, which were beneficial to increase engine thermal efficiency and improve engine room environment. Compared with the engine running in pure diesel mode, when the engine ran in diesel/methanol dual fuel mode, the combustion phase was advanced, and the combustion duration became shorter. Therefore, the engine thermal efficiency increased, and fuel consumption decreased significantly. 相似文献
13.
Biogenic volatile organic compounds (BVOCs) in the atmosphere play important roles in the formation of ground-level ozone and secondary organic aerosol (SOA) in global scale and also in regional scale under some condition due to their large amount and relatively higher reactivity. In places with high plant cover in the tropics and in China where air pollution is serious, the effect of BVOCs on ozone and secondary organic aerosols is strong. The present research aims to provide a comprehensive review about the emission rate, emission inventory, research methods, the influencing factors of BVOCs emissions, as well as their impacts on atmospheric environment quality and human health in recent years in Asia based on the summary and analysis of literatures. It is suggested to use field direct measurement method to obtain the emission rate and model method to calculate the emission amount. Several recommendations are given for future investigation and policy development on BVOCs emission. 相似文献
14.
2019年10~12月京津冀及周边“2+26”城市重污染减排效果评估 总被引:7,自引:6,他引:1
为评估京津冀及周边区域重污染过程期间应急减排措施的效果,基于情景模拟的方法,采用NAQPMS模式和多种观测资料,分析了2019年10~12月期间京津冀及周边区域环境空气质量、重污染过程和气象条件概况,评估了模式24、72和144 h的PM2.5预报效果,并对应急减排措施的效果和不确定性进行了讨论.结果表明,2019年10~12月京津冀及周边"2+26"城市PM2.5平均浓度64 μg ·m-3,同比降低了10 μg ·m-3;区域性重污染过程4次,受影响城市重污染过程期间PM2.5平均浓度156 μg ·m-3."2+26"城市PM2.5气象条件评估指数(EMI)变化值范围为-15.6%~16.8%,EMI显示北京、天津和石家庄等12个城市气象条件与同期相比变差,变差程度范围为3.2%~16.8%.减排情景模拟分析显示应急减排措施有效减少了区域性重污染过程的发生,污染物峰值浓度降幅明显,未出现区域性严重污染过程.典型重污染期间,北京、石家庄、保定和唐山等城市PM2.5日均浓度削减2%~9%.区域应急减排措施促使"2+26"城市PM2.5季度均值分别降低1~3 μg ·m-3左右,区域性减排效果明显. 相似文献
15.
德州市夏季臭氧敏感性特征及减排方案 总被引:9,自引:9,他引:0
近年来德州市臭氧污染频发,2018年夏季(6~8月),德州市发生了严重臭氧污染事件,臭氧日最大8 h浓度值超标天数达60 d,超标率65%,3个月平均值为176 μg ·m-3,最高达262 μg ·m-3.本研究利用WRF-CAMx耦合的HDDM模块,分析期间德州臭氧敏感性特征及减排方案.结果表明,在空间上,德州市中心城区为VOCs控制区,而郊区为NOx与VOCs协同控制区.在时间上,VOCs敏感值每日为正值,但dO3_V50在6月(城区18.7 μg ·m-3,郊区19.7 μg ·m-3)和8月(城区15.3 μg ·m-3,郊区16.4 μg ·m-3)高于7月(城区13.0 μg ·m-3,郊区11.8 μg ·m-3),NOx敏感值城区呈正负交错,郊区大部分为正值,并与VOCs敏感值接近.对于城区减排方案应考虑以仅VOCs削减为优先,而郊区由于NOx和VOCs对臭氧减排效果相当,建议以NOx:VOCs=1:1为优. 相似文献
16.
Qingru Wu Shuxiao Wang Mei Yang Haitao Su Guoliang Li Yi Tang Jiming Hao 《环境科学学报(英文版)》2018,30(6):91-99
Large-scale gold production(LSGP) is one of the five convention-related atmospheric mercury(Hg) emission sources in the Minamata Convention on Mercury. However, field experiments on Hg flows of the whole process of LSGP are limited. To identify the atmospheric Hg emission points and understand Hg emission characteristics of LSGP, Hg flows in two gold smelters were studied. Overall atmospheric Hg emissions accounted for 10%–17% of total Hg outputs and the Hg emission factors for all processes were 7.6–9.6 kg/ton. There were three dominant atmospheric Hg emission points in the studied gold smelters, including the exhaust gas of the roasting process, exhaust gas from the environmental fog collection stack and exhaust gas from the converter of the refining process. Atmospheric Hg emissions from the roasting process only accounted for 16%–29% of total emissions and the rest were emitted from the refining process. The overall Hg speciation profile(gaseous elemental Hg/gaseous oxidized Hg/particulate-bound Hg) for LSGP was 34.1/57.1/8.8. The dominant Hg output byproducts included waste acid, sulfuric acid and cyanide leaching residue. Total Hg outputs from these three byproducts were 80% in smelter A and 84% in smelter B. Our study indicated that previous atmospheric Hg emissions from large-scale gold production might have been overestimated.Hg emission control in LSGP is not especially urgent in China compared to other significant emission sources(e.g., cement plants). Instead, LSGP is a potential Hg release source due to the high Hg output proportions to acid and sludge. 相似文献
17.
ADMS模型解析城区总悬浮颗粒物来源 总被引:1,自引:1,他引:1
以污染源排放数据为基础,应用ADMS-城市扩散模型模拟分析了鞍山市尘各污染源对空气环境质量的贡献。结果表明,来自污染源的浓度贡献值占总量的52%;二次尘及外来尘浓度贡献占48%;矿山开采二次尘的浓度贡献占16%;鞍钢炼铁厂的浓度贡献占19.6%;鞍钢化工总厂浓度贡献占5.6%;供暖锅炉浓度贡献占9.3%。低、中、高架源浓度贡献百分比分别为68.1%、29.0%、2.9%。低架源吨排放量浓度贡献为高架源的2.4倍。 相似文献
18.
Air pollution problems in developing countries have gained larger fraction in the last decade especially due to non functioning and non implementation of effective air pollutioncontrol devices in industries. In industrial wastewater management, adequate treatability studies are conducted to arrive at a techno-economic treatment option. However no suchstudies were done for reducing air pollution or emission fromindustries until now in India. Little information was availableabout such studies in other countries. This article provides information about a novel technique known asflue gas treatability studies and to undertake such studies, a pilot scale system is installed in Air Pollution Control Divisionof M/s National Environmental Engineering research Institute, NEERI, Nagpur-20, India. This study is a tool for techno-economicselection of air pollution control systems specially for small/medium scale industrial emissions. 相似文献
19.
CHEN Wen-ying 《环境科学学报(英文版)》2003,15(4):541-547
Emission projection and marginal abatement cost curves (MACs) are the central components of any assessment of future carbonmarket, such as CDM (clean development mechanism) potentials, carbon quota price etc. However, they are products of very complex,dynamic systems driven by forces like population growth, economic development, resource endowments, technology progress and so on. The modeling approaches for emission projection and MACs evaluation were summarized, and some major models and their results were compared.Accordingly, reduction and cost requirements to achieve the Kyoto target were estimated. It is concluded that Annex I Parties‘ total reduction requirements range from 503--1304 MtC with USA participation and decrease significantly to 140--612 MtC after USA‘ s withdrawal. Total costs vary from 21--77 BUSD with USA and from 5--36 BUSD without USA if only domestic reduction actions are taken. The costs would sharply reduce while considering the three flexible mechanisms defined in the Kyoto Protocol with domestic actions‘ share in the all mitigation strategies drons to only 0--16%. 相似文献
20.