V2O5/TiO2催化剂中毒机理的试验研究

选择性催化还原(SCR)催化剂是SCR烟气脱硝技术的核心,是整个SCR系统脱硝效率和经济性的决定因素.本文工作的主要研究思路是以钒钛SCR催化剂为研究对象,研究了H2O和SO2,以及相同含量下K、Na、Ca、Pb的氧化物对钒钛催化剂NO转化率的影响.H2O的存在会抑制V2O5/TiO2催化剂脱硝活性,而SO2在一定程度上促进(V2O5/TiO2)催化剂的SCR脱硝反应,提高NO转化率;碱金属K对钒钛催化剂的钝化作用都是最强,K2O和Na2O的掺入会抑制钒钛催化剂上V2O5的还原能力,而CaO和PbO的掺入对钒钛催化剂上V2O5的还原能力影响较小.     

多层填料生物转鼓去除NO废气的效能比较研究

生物转鼓过滤器能有效去除一氧化氮(NO)废气,为进一步提高生物转鼓过滤器的去除效能,实验改变了生物转鼓的填料结构,并与单层填料的生物转鼓进行了比较研究.结果表明,多层填料生物转鼓比单层填料生物转鼓更能有效去除NO,运行也更加稳定.8个月的连续运行实验表明,多层填料生物转鼓对NO去除率稳定在53.9％ ～93.4％之间,平均去除效率79.8％,而单层填料生物转鼓的平均去除率仅有68.7％;在相同实验条件下,空床停留时间(EBRT)可从单层填料生物转鼓的86.4 s降至多层填料生物转鼓的57.6 s.多层填料生物转鼓的最优工艺条件为,营养液量为1.3～3L,转速为0.75 r·min-1,在以葡萄糖为碳源时,TOC＞ 1250 mg·L-1后,去除效率增长幅度趋于平缓.     

Effect of ammonium on nitrous oxide emission during denitrification with different electron donors

Nitrous oxide(N2O) emission during denitrification is receiving intensive attention due to its high potential to cause greenhouse effects.In this study,denitrifiers were acclimated in sequencing batch reactors with methanol or acetate as the electron donor and nitrate as the electron acceptor.The effects of ammonium on N2O emission were examined in batch experiments with various electron donors.With the addition of ammonium,N2O emission increased under all the examined conditions compared to experiments without ammonium addition.With different electron donors,the highest ratio of N2O emission to the removed oxidized nitrogen was 0.70% for methanol,5.34% for acetate,and 34.79% for polyhydroxybutyrate.     

乙醇处理对树脂基纳米水合氧化铁结构及其除砷性能的影响

通过考察乙醇处理对树脂基纳米水合氧化铁(D201-HFO)结构及其除砷性能的影响,评价乙醇处理在复合材料制备中的必要性.结果表明,乙醇处理后负载水合氧化铁(HFO)在D201树脂内的分散性增加,材料对砷的饱和吸附量提高约20%,且复合材料的比表面积、孔容、孔径分别增加了52%、65%、28%;但乙醇处理对复合材料的机械强度和负载HFO的晶型无影响,在pH值、离子竞争对该材料除砷性能的影响趋势方面也无明显作用,对复合材料固定床除砷性能及再生方面也无明显作用.总体而言,乙醇处理对D201-HFO复合材料实际除砷性能影响不大,从技术经济性考虑可以省略.     

Managing a forgotten greenhouse gas under existing U.S. law: An interdisciplinary analysis

The United States’ legal strategy for addressing climate change in recent years has relied on authority from existing legislation. This has led to measures on a number of different greenhouse gases, notably carbon dioxide, methane and hydrofluorocarbons. However, one greenhouse gas has been largely forgotten: nitrous oxide. Nitrous oxide is the third most abundantly emitted greenhouse gas in the U.S. and worldwide, as well as the largest remaining threat to the stratospheric ozone layer. In addition, the nitrogen atoms in nitrous oxide are part of the highly fluid nitrogen cycle where nitrogen atoms transform readily among different chemical forms, each with a unique environmental and human health impact – a process known as the nitrogen cascade. While the science of the nitrogen cascade has been explored for over a decade, there has been little work on the legal implications of this phenomenon. And yet the nitrogen cascade expands the legal options available for controlling nitrous oxide. This paper studies these options in a U.S. context and explores the environmental and economic impacts of enacting them. We determine that the Clean Air Act, and in particular its broad authority for controlling ozone depleting substances, is the most promising legal pathway for regulating nitrous oxide across all major sources. Invoking such authority could generate significant climate and stratospheric ozone benefits over 2015–2030, equivalent to taking 12 million cars permanently off the road, and 100 million chlorofluorocarbon-laden refrigerators out of service. The economic benefits could sum to over $700 billion over 2015–2030, with every $1.00 spent on abating emissions leading to $4.10 in societal benefits. The bulk of these benefits would come from reductions in other forms of nitrogen pollution such as ammonia and nitrate, highlighting the important and multiple co-benefits that could be achieved by abating nitrous oxide emissions. With the Paris Climate Agreement calling for limiting global temperature increases to “well below” two degrees Celsius, all mitigation opportunities across all sectors need to be considered. This paper suggests that nitrous oxide warrants more attention from policy-makers in the U.S. and around the world.     

NOx分解还原催化研究进展

介绍和评价了ＮＯ_ｘ分解还原的３类催化剂：贵金属催化剂、氧化物催化剂、金属离子置换的分子筛。在ＮＯ_ｘ的碳氢化合物选择性催化还原反应（ＨＣ－ＳＣＲ反应）中，同样有３类催化剂，即金属氧化物、贵金属和分子筛。由于Ｃｕ－ＺＳＭ－５是目前最有希望投入实际使用的一种，故本文重点介绍了它对ＮＯ_ｘ的ＨＣ－ＳＣＲ反应的催化机理，以及温度、Ｏ_２含量、Ｃｕ~（２＋）的置换度、不同种类ＨＣ及ＨＣ含量等各种因素对Ｃｕ－ＺＳＭ－５的影响，并对其工作台试验进行了评价，指出了其存在的问题及当前的研究热点。     

钠盐量影响下DD6单晶高温合金的高温热腐蚀规律研究

目的 开展镍基单晶高温合金DD6在950 ℃下的热盐腐蚀试验(95%Na2SO4+5%NaCl)，探明涂盐量和涂盐方式(周期涂盐和单次涂盐)对DD6高温热腐蚀的影响规律和机理。方法 结合扫描电子显微镜、X射线能量色散谱、X射线衍射等设备，对不同涂盐量及涂盐方式下DD6的表面及横截面形貌进行观察分析，分析不同涂盐量和涂盐方式下DD6的高温热腐蚀机理。结果 DD6在950 ℃下主要发生碱性熔融热腐蚀，同时伴随氧化、硫化和氯化等过程。高温热腐蚀使得DD6合金表面生成的保护性氧化膜被熔融态的腐蚀介质破坏，导致O、S、Cl等外部元素通过氧化膜的缺陷进入DD6基体中，在合金的亚表面发生内氧化、内硫化以及内氯化反应，横截面上出现明显的腐蚀层，其主要由氧化物以及硫化物组成。随着热腐蚀的进行，DD6表面物质发生了剥蚀，沉积盐量的增加导致剥蚀现象越加严重，合金内部致密的组织结构也被破坏，横截面上出现了大量孔洞、裂纹等缺陷。在相同涂盐量下，周期涂盐法使得DD6的腐蚀程度高于单次涂盐法。结论 DD6高温热腐蚀行为与涂盐量及涂盐方式密切相关，相同涂盐方式下，涂盐量越大，DD6热腐蚀更加严重。涂盐量一定时，周期涂盐法使得DD6的热腐蚀剧烈程度大于单次涂盐法，且DD6在上述热腐蚀条件下均发生剥蚀破坏。     

Role of nitric oxide in the genotoxic response to chronic microcystin-LR exposure in human–hamster hybrid cells

Microcystin-LR(MC-LR) is the most abundant and toxic microcystin congener and has been classified as a potential human carcinogen(Group 2B) by the International Agency for Research on Cancer. However, the mechanisms underlying the genotoxic effects of MC-LR during chronic exposure are still poorly understood. In the present study, human–hamster hybrid(AL) cells were exposed to MC-LR for varying lengths of time to investigate the role of nitrogen radicals in MC-LR-induced genotoxicity. The mutagenic potential at the CD59 locus was more than 2-fold higher(p 0.01) in ALcells exposed to a cytotoxic concentration(1 μmol/L) of MC-LR for 30 days than in untreated control cells, which was consistent with the formation of micronucleus. MC-LR caused a dose-dependent increase in nitric oxide(NO) production in treated cells. Moreover, this was blocked by concurrent treatment with the NO synthase inhibitor NG-methyl-L-arginine(L-NMMA), which suppressed MC-LRinduced mutations as well. The survival of mitochondrial DNA-depleted(ρ0) ALcells was markedly decreased by MC-LR treatment compared to that in ALcells, while the CD59 mutant fraction was unaltered. These results provided clear evidence that the genotoxicity associated with chronic MC-LR exposure in mammalian cells was mediated by NO and might be considered as a basis for the development of therapeutics that prevent carcinogenesis.     

CaH_2对Cu-Ce-La-ZSM-5催化分解NO性能的影响

实验采用一步离子交换法制备Cu-Ce-La-ZSM-5催化剂,然后采用共混法制得Cu-Ce-La-ZSM-5/CaH2催化剂。采用扫描电镜(SEM),电感耦合等离子体发射光谱(ICP-AES),X射线衍射(XRD),红外(FTIR)以及NO吸脱附(NO-TPD)对催化剂进行表征。结果显示CaH2的加入使得催化剂中铜离子存在形式发生变化,催化剂表面变光滑洁净,并且吸附NO能力增强。NO催化分解实验的结果表明CaH2提高了催化剂活性和抗氧性。CaH2助催性是由于其受热分解过程中产生的H2能将Cu2+还原为具有催化活性的Cu+,同时使催化剂表面洁净光滑更容易吸附NO。     

用碳化法从制碱废渣一次盐泥中制取轻质氧化镁的研究

本研究是用制碱废渣一次盐泥作原料，采用二氧化碳碳化法制取轻质氧化镁。同时分析了提取轻质氧化镁后的残渣用于制造水泥或其它胶凝材料的原料的可行性。