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Yong-Zhao Wang Yong-Xiang Zhao Chun-Guang Gao Dian-Sheng Liu 《Catalysis Letters》2007,116(3-4):136-142
Without use of any surfactant or oxidant, a series of Co3O4 catalysts have been prepared from cobalt nitrate aqueous solution via a very simple liquid-precipitation method with ammonium
acid carbonate followed by calcination at various temperatures. The catalytic performance of the Co3O4 for CO oxidation has been studied with a continuous flowing laboratory microreactor system. The results show that the CO
conversion of all the samples can reach 100% at ambient temperature. The catalyst calcined at 300 °C is able to maintain its
activity for CO complete oxidation more than 500 min at 25 °C and about 240 min even at −78 °C. High reaction temperature
results in a high catalytic stability, while the catalytic stability decreases with further increasing the reaction temperature.
Characterizations with X-ray powder diffraction and transmission electron microscopy suggest that all the samples exist as
a pure Co3O4 phase with the spinel structure, the samples are apt to aggregate and the specific surface area gradually decreases with
increasing the calcination temperature, which directly leads to the decrease of catalytic stability. Furthermore, the amount
of active oxygen species measured by CO titration experiments appears to be critical for catalytic performance. 相似文献
6.
将变换流程改为全低变工艺后,吨氨蒸汽消耗明显下降,但触媒床层阻力迅速上升.通过采取增设焦炭过滤器、更换触媒、改进蒸汽分布器等一系列措施,不仅保证了正常的生产指标,而且还使变换炉的阻力有了明显下降,取得了满意的效果. 相似文献
7.
研究了不同老化方式对沥青低温性能的影响,分3个阶段,对不同老化方式的试验结果进行了比较.阶段1研究表明,沥青在压力老化容器(PAV)中100℃条件下老化20 h后的低温性能与在1.01×105Pa、60℃条件下老化38 d后的低温性能相差无几.阶段2研究表明,可以通过58℃、10 r/s时的高温因子G*/sinδ来修正低温性能分级,从而可以利用短期老化来代替长期老化试验.阶段3研究表明,沥青的低温性能会随着老化时间改变而变化.当老化时间较短时,低温性能分级由劲度指标控制;当老化时间较长时,低温性能分级将转变为由蠕变速率控制. 相似文献
8.
Bioremediation of polycyclic aromatic hydrocarbons: current knowledge and future directions 总被引:1,自引:0,他引:1
Selina M Bamforth Ian Singleton 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(7):723-736
Polycyclic aromatic hydrocarbons (PAHs) are a class of organic compounds that have accumulated in the natural environment mainly as a result of anthropogenic activities such as the combustion of fossil fuels. Interest has surrounded the occurrence and distribution of PAHs for many decades due to their potentially harmful effects to human health. This concern has prompted researchers to address ways to detoxify/remove these organic compounds from the natural environment. Bioremediation is one approach that has been used to remediate contaminated land and waters, and promotes the natural attenuation of the contaminants using the in situ microbial community of the site. This review discusses the variety of fungi and bacteria that are capable of these transformations, describes the major aerobic and anaerobic breakdown pathways, and highlights some of the bioremediation technologies that are currently available. Copyright © 2005 Society of Chemical Industry 相似文献
9.
生物质与煤共燃研究(Ⅰ)生物质的低温热解 总被引:6,自引:4,他引:6
介绍了生物质与煤共燃的研究流程及其主要的研究方法,通过对三种主要农业剩余生物质(锯屑,谷壳和花生壳)热解过程中的失重率变化,物理性质变化,工业分析变化,元素分析变化和发热量变化的研究发现,三种生物质在热解温度220℃-300℃,热解时间30min-60min下进行低温热解时,热解过程主要受热解温度控制,受热解时间控制较弱,随热解温度升高,热解时间延长,生物质的热失重率逐渐升高,生物质逐渐变得易于研磨。在工业分析上挥发分逐渐减少,固定碳及灰分不断提高,水分含量大幅下降;在元素分析上O元素的含量不断下降,C元素的含量不断上升,从而发热量不断增加,研究表明,当热解温度为270℃-300℃时,热解生物质的各项性质可与煤接近。 相似文献
10.
The effect of preparation method on MnO
x
–CeO2 mixed oxide catalysts for methane combustion at low temperature was investigated by means of BET, XRD, XPS, H2-TPR techniques and methane oxidation reaction. The catalysts were prepared by the conventional coprecipitation, plasma and
modified coprecipitation methods, respectively. It was found that the catalyst prepared by modified coprecipitation was the
most active, over which methane conversion reached 90% at a temperature as low as 390 °C. The XRD results showed the preparation
methods had no effect on the solid solution structure of MnO
x
–CeO2 catalysts. More Mn4+ and richer lattice oxygen were found on the surface of the modified coprecipitation prepared catalyst with the help of XPS
analysis, and its reduction and BET surface area were remarkably promoted. These factors could be responsible for its higher
activity for methane combustion at low temperature. 相似文献