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1.
含钐萤石型复氧化物的制备法及甲其烷燃烧性能   总被引:2,自引:0,他引:2  
含钐的锆基萤石型复氧化物与镧系钙化钛矿型化合物一样,表现出良好的促进甲烷完全燃烧的催化活性,无论从单位质量,单位表面积的甲烷转化率或是起燃温度上比较,前者都不逊色,且有良好的高温性能,这种新材料催化活性与其制备技术密切相关,其中碳酸盐共沉淀法,有机酸的化学混合法可以得到很好的结果,而氢氧化物共沉淀法却差得多。  相似文献   

2.
用共沉淀法制备了Ba0 8La0. 2MnAl11O19催化剂,并借助XRD、BET和SEM技术对其进行了表征,利用微型反应系统测定了催化剂的甲烷燃烧催化活性,研究了不同空速、烷氧比、甲烷体积分数下Ba0. 8La0. 2MnAl11O19的活性.结果表明,当空速为150 000h-1、烷氧比为1 /6、甲烷体积分数为3%时,甲烷燃烧的催化活性最好,完全转化温度为760℃.  相似文献   

3.
S2O8^2-/ZrO2-SiO2类固体超强酸催化剂制备条件的研究   总被引:4,自引:0,他引:4  
采用共沉淀浸渍法与沉淀一混合共沉淀浸渍法考察了不同制备方法以及不同稀土种类等不同制备条件下的S2O8^2-/ZrO2-SiO2类固体超强酸催化剂的催化活性.结果表明:沉淀一混合共沉淀浸渍法制备的催化剂活性远远大于共沉淀浸渍法制备的催化剂的活性.  相似文献   

4.
选择性催化氧化H2S的催化剂研究   总被引:1,自引:0,他引:1  
在考察了几种单组分氧化物把硫化氢催化氧化为单质硫的基础上,采用共沉淀法合成了3种复合氧化物催化剂A,B,C,并考察了它们的催化活性和选择性.结果表明,在一定条件下,催化剂B的转化率和选择性分别在90%和97%以上,在40h的催化性能稳定性测试中,其转化率和选择性均能保持稳定,具有良好的催化性能.  相似文献   

5.
为了研制用于从天然气制取乙烯的,具有良好的催化活性、选择性和稳定性的催化剂,用溶胶-凝胶法合成了系列稀上-锡复合氧化物La2-xSmxSn2O7(x=0.0,0.5,1.0,1.5,2.0).用xRD对其结构研究表明:La2-xSinxSn2O7,系列稀土-锡复合氧化物均具有烧绿石型结构,属立方晶系,空间群为F3dm.同时发现其晶胞参数apyr随Sm掺入量增加而近乎线性减小.并在脉冲激反应器上,对其催化活性进行评价.结果表明:Sm2Sn2O7复合氧化物对甲烷氧化偶联反应具有良好的催化活性,在CH4/O2=4,温度在800℃~900℃,X=2.0时,C2选择性为38.1%,产率为9.2%,其中C2=的选择性为27.9%,产率为6.4%.同时发现晶格缺陷的形成有利于催化剂催化活性的提高.  相似文献   

6.
采用共沉淀浸渍法与沉淀-混合共沉淀浸渍法考察了不同制备方法以及不同稀土种类等不同制备条件下的S2O82-/Z rO2-S iO2类固体超强酸催化剂的催化活性.结果表明:沉淀-混合共沉淀浸渍法制备的催化剂活性远远大于共沉淀浸渍法制备的催化剂的活性.  相似文献   

7.
S2O2-8/ZrO2-SiO2类固体超强酸催化剂制备条件的研究   总被引:3,自引:0,他引:3  
采用共沉淀浸渍法与沉淀-混合共沉淀浸渍法考察了不同制备方法以及不同稀土种类等不同制备条件下的S2O2-8/ZrO2-SiO2类固体超强酸催化剂的催化活性.结果表明:沉淀-混合共沉淀浸渍法制备的催化剂活性远远大于共沉淀浸渍法制备的催化剂的活性.  相似文献   

8.
本文综述了用凝聚法去除三卤甲烷潜值(THMFP)的三种作用机理:胶体脱稳机理、沉淀作用机理及共沉淀作用机理.在此基础上,分析了凝聚剂种类及投量、原水水质及Ph等因素对凝聚效果的影响.  相似文献   

9.
纳米ZnFe_2O_4粉体合成及甲烷催化燃烧性能研究   总被引:1,自引:0,他引:1  
采用草酸共沉淀法制备了纳米ZnFe2O4粉体,分别用XRD,SEM,XPS等手段对所合成样品的相结构、微观形貌、表面元素状态进行了表征.固定床催化实验表明,ZnFe2O4催化剂具有较高的甲烷燃烧催化活性,甲烷起燃温度T10约为368℃.Fe 2p和O 1s XPS结果显示,催化剂表面含有部分Fe2+及相当可观的吸附氧物种,表明催化剂表面存在着大量氧空位.这些氧空位有利于气态氧分子在固体表面吸附并产生活性氧物种,可以在较低的温度使甲烷氧化.  相似文献   

10.
综述了乙酸仲丁酯合成中各种催化剂的应用.结果表明,强酸性阳离子交换树脂、固体超强酸、对甲基苯磺酸、二苯胺甲烷磺酸盐和壳聚糖硫酸盐对合成乙酸仲丁酯具有良好的催化活性,酯化率较高,具有良好的应用前景.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

18.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

19.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

20.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

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