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621.
V2O5/TiO2催化剂选择性催化还原脱除NOx的研究 总被引:8,自引:1,他引:7
通过浸渍法制备V2O5/TiO2催化剂,在固定床反应器中进行NH3选择性催化还原脱除NOx的研究.结果表明,对于100/140目催化剂,NOx转化率随反应时间线性增加,NH3选择性催化还原NOx反应为一级反应,反应活化能为98.23 kJ*mol-1.对于片状催化剂,气体流量和催化剂的厚度对脱氮反应有较大的影响,气体流量增加,NOx转化率提高,当流量增至120 L*h-1后,NOx转化率趋于稳定;催化剂厚度由0.1 cm增至0.2 cm, NOx转化率从83%降至40%, 催化剂有效因子从0.254降至0.127.对于0.1 cm厚的片状催化剂,在573 K和空速1.4 s-1条件下,NOx转化率可达92%. 相似文献
622.
车用催化转化器起燃温度的数值模拟 总被引:1,自引:0,他引:1
车用催化转化器是降低汽车排气污染物浓度的主要装置.起燃温度是催化转化器的重要特性之一,它表明催化器在多高的温度下有较高转化率.数值模拟研究催化转化器的性能可以减少实验量,指导和优化催化器的设计.建立了催化转化器一维稳态转化率的数学模型,对起燃温度特性曲线进行模拟.数值模拟结果与实验测量值较吻合.这说明,建立的数学模型可以用来模拟起燃温度特性曲线.用该模型考察了空速、载体长度、催化剂比表面积、载体导热系数以及壁厚等因素对起燃温度特性曲线的影响.结果表明,空速越大,催化转化器的起燃温度越高;增大载体长度和催化剂比表面积有利于降低起燃温度;载体导热系数和壁厚的大小对起燃温度几乎没有影响. 相似文献
623.
A. Matsuki Y. Iwasaka G.-Y. Shi H.-B. Chen K. Osada D. Zhang M. Kido Y. Inomata Y.-S. Kim D. Trochkine C. Nishita M. Yamada T. Nagatani M. Nagatani H. Nakata 《Water, Air, & Soil Pollution: Focus》2005,5(3-6):101-132
This study focuses on providing a direct insight into the process by which sulfate is formed on mineral dust surface in the
actual atmosphere. Six sets of aerosol measurements were conducted in the outskirts of Beijing, China, in 2002–2003 using
a tethered balloon. The mineralogy of individual dust particles, as well as its influence on the S (sulfur) loadings was investigated
by SEM-EDX analysis of the directly collected particles.
The mixed layer in the urban atmosphere was found to be quite low (500–600m), often appearing as a particle dense stagnant
layer above the surface. It is suggested that mineral dust is a common and important fraction of the coarse particles in Beijing
(35–68%), and that it is relatively enriched with Calcite (>28%).
An exceptional amount of S was detected in the mineral particles, which can be explained neither by their original composition,
nor by coagulation processes between the submicron sulfates and the dust. Heterogeneous uptake of gaseous SO2, and its subsequent oxidation on dust was suggested as the main pathway that has actually taken place in the ambient environment.
The mineral class found with the largest number of particles containing S was Calcite, followed by Dolomite, Clay, Amphibole
etc., Feldspar, and Quartz. Among them, Calcite and Dolomite showed distinctly higher efficiency in collecting sulfate than
the other types.
A positive correlation was found with the number of S containing particles and the relative humidity. Calcite in particular,
since almost all of its particles was found to contain S above 60% r.h. On the other hand, the active uptake of SO2 by the carbonates was not suggested in the free troposphere downwind, and all the mineral classes exhibited similar S content.
Relative humidity in the free troposphere was suggested as the key factor controlling the SO2 uptake among the mineral types. In terms of sulfate loadings, the relationship was not linear, but rather increased exponentially
as a function of relative humidity. The humidity-dependent uptake capacity of mineral types altogether showed an intermediate
value of 0.07 gSO4
2− g−1 mineral at 30% r.h. and 0.40 gSO4
2− g−1 mineral at 80%, which is fairly consistent with laboratory experiments. 相似文献
624.
Shing-Fu Hsueh Robert C. Ahlert 《Journal of the American Water Resources Association》1978,14(6):1404-1416
ABSTRACT: An input-output method, using a network of ideal continuous stirred-tank and plug-flow tublar reactors, is adopted to analyze residence time distribution data for a separated mechanical aeration system. The usefulness of this modeling concept is enhanced by its simplicity, especially in the presence of a first-order reaction. This facilitates use of the model format for wastewater quality prediction. Moreover, first-order rate constants can also be estimated from the model, if conversions due to the reaction rate are available. 相似文献
625.
不同主体的旅游开发对社会的影响--以云南石林景区为例 总被引:3,自引:0,他引:3
采用问卷调查和新测量模型相结合的方式对云南石林景区进行了实证研究,比较分析了旅游地居民和旅游者对旅游开发活动带来的旅游社会影响的不同态度,得出不同的主体对旅游社会影响的态度差异性和趋同性,并提出了具体的对策和实现途径,以期为下一步的旅游调整性规划提供有益参考. 相似文献
626.
氯乙酸母液氢解制氯乙酸 总被引:2,自引:0,他引:2
以氯乙酸母液和氢气为原料,开发了氢解制氯乙酸的新工艺。文中介绍了氢解了反应原理和工艺流程,并介绍了母液预处理,催化剂筛选及氢解反应条件等试验。中试验连续运转的结果表明,工艺路线合理可行,催化剂活性稳定,单程氢解产品产率达到94%以上,产品氯乙酸的质量达到行业标准,装置运行安全可靠。 相似文献
627.
硝酸及氯离子对高温硝酸铵水溶液热危险性的影响研究 总被引:3,自引:1,他引:3
国内外学者对硝酸铵的危险性进行了大量的研究,而对其水溶液的危险性至今开展不多。笔者采用差示扫描量热仪(DSC)及全自动反应量热仪(RC1e)对高温状态下的硝酸铵水溶液的热分解危险性、杂质离子对其稳定性的影响进行了研究。纯硝酸铵和90%硝酸铵水溶液的DSC实验表明,90%硝酸铵溶液和分析纯硝酸铵具有相似的热爆炸危险;90%硝酸铵水溶液在140~180℃之间的RC1e试验表明:硝酸或氯离子单独存在时,对硝酸铵分解都有不同程度的抑制作用,而同时存在时则大大降低体系的热稳定性。该结果对保障硝酸铵在生产、使用过程中的安全具有重要的参考价值。 相似文献
628.
629.
城市污水二级处理出水中沙门氏菌的PCR检测 总被引:1,自引:0,他引:1
建立了一种利用PCR检测城市污水二级处理出水中沙门氏菌的方法.采用膜吸附-洗脱法浓缩二级出水水样中的沙门氏菌,通过选用一对涵盖性和特异性均较强的引物139和141,对浓缩后的沙门氏菌进行PCR检测.利用正交试验法,对沙门氏菌PCR体系进行五因素四水平的试验,建立了沙门氏菌PCR的最佳体系.通过梯度PCR考察了退火温度对检测结果的影响,选择65℃作为退火温度,优化后沙门氏菌PCR体系的检测灵敏度可达0.314ngL.通过对已知细菌浓度的水样进行检测,确定了该法检测水样中沙门氏菌的灵敏度为2130CFUL.与传统MPN法的相比,该法在检测效果和检测效率上都优于MPN法. 相似文献
630.
Mingqiang Huang Weijun Zhang Liqing Hao Zhenya Wang Li Fang Ruihong Kong Xiaobin Shan Fuyi Liu Liusi Sheng 《环境科学学报(英文版)》2010,22(10)
Smog chamber experiments were performed to investigate the composition of products formed from photooxidation of aromatic hydrocarbon ethylbenzene.Vacuum ultraviolet photoionization mass spectrometer and aerosol time-of-flight mass spectrometer were used to measure the products in the gas and particle phases in real-time.Experimental results demonstrated that ethylphenol,methylglyoxal,phenol,benzaldehyde,and 2-ethylfurane were the predominant photooxidation products in both the gas and particle phases.However,there were some differences between detected gas phase products and those of particle phase,for example,2-ethylfurane,ethylglyoxylie acid,nitroethylbenzene,3,4-dioxopentanal and ethyl-nitrophenol were only existing in the particle-phase.The possible reaction mechanisms leading to these products were also discussed and proposed. 相似文献