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1.
采用X射线衍射、比表面测试、光电子能谱和电镜扫描等现代表征手段,对经不同硫化反应时间后所得到的钼、铁二元金属催化剂进行表征。研究发现,虽然硫化时间的延长可提高催化剂中金属组分的硫化物含量,但超过一定反应时间可导致硫化物过度结晶聚集,颗粒度增大,比表面下降,较佳的反应时间为60~90min。Mo-Fe、Ni—Fe二元复合催化剂及Mo-Ni—Fe三元复合催化剂的最佳摩尔配比分别为1:73,1:80,1:2:110。  相似文献   

2.
采用热重分析、差热分析和光电子能谱对有代表性的Fe、Co和Mo等7种过渡金属催化剂进行表征,研究了CO还原SO,的反应机理和催化荆的催化作用机理及相关的影响因素.结果表明,活性组分不同、负载量相同的催化剂在进行催化反应后表面组成差异较大,S元素的表面分布状态与金属元素密切相关,催化剂表面上金属元素越多,其相应S含量也越高;金属氧化物的硫化路径是先还原后硫化,易于还原的物质更易于硫化;催化活性与空定分数机、金属硫化物键能和金属元素的电负性有关,仅从过渡金属的空穴分数机或各金属硫化物的键能参数难以获得各金属催化剂的催化活性规律,实验表明各金属离子的电负性参数与其催化活性之间存在相关规律.  相似文献   

3.
复合负载金属-支撑水相催化剂上1-己烯氢甲酰化反应性能   总被引:2,自引:0,他引:2  
利用均相催化剂和多相催化剂各自的特点,首先在高比表面大孔硅胶负载金属催化剂上担载水相络合催化剂制备复合负载金属-支撑水相催化剂。同时,对负载金属催化剂、支撑水相催化剂和复合负载金属-支撑水相催化剂上的1-己烯氢甲酰化进行了考察。结果表明,多相金属组分对提高复合负载金属-支撑水相催化剂上1-己烯氢甲酰化的活性和选择性具有明显促进作用,复合催化剂中均相组分和多相组分具有协同作用。  相似文献   

4.
针对非均相贵重金属催化剂成本高,非均相过渡金属催化剂性能良好、成本低,但使用寿命短、易流失的特点,研制高效复合MnO2-Cu O-CeO2非均相过渡金属催化剂.采用正交实验对催化剂制备过程中的n(Cu)∶n(Mn)、Ce的摩尔分数、焙烧温度、焙烧时间进行探讨,确定最佳制备条件,并对其结构和组成通过扫描电镜分析、X射线衍射分析及热重分析进行表征.用该催化剂催化氧化模拟苯酚废水,对催化剂用量、氧化剂H2O2用量、反应温度、反应时间进行优化,确定最佳反应条件并利用其进行降解化工集装罐清洗废水的应用研究.研究表明催化剂MnO2-Cu O-CeO2的最佳制备条件为:n(Cu)∶n(Mn)=4∶6、Ce的摩尔分数为10%、焙烧温度为600,℃、焙烧时间为4,h.催化氧化法处理苯酚废水的最佳工艺参数:催化剂用量0.8,g/L、H2O2用量与COD比值为3、反应温度170,℃、反应时间1,h.化工集装罐清洗废水COD去除效果显著,COD去除率达到95%左右.  相似文献   

5.
对以二氯丙醇环合反应生产环氧氯丙烷过程中所采用的催化剂进行了研究.采用溶胶凝胶法制备了不同种类的固体超强碱催化剂,并考察了这些催化剂的组分配比、焙烧温度等因素对催化剂性能的影响.其中对于组分为BaK/γ-Al2O3的固体超强碱催化剂,在焙烧温度为600℃、Ba∶K∶Al=4∶1∶10,反应温度为125℃时其催化活性最高.采用气相色谱分析法对产品进行表征,测得1,3-DCH转化率和ECH收率可达到80.03%和74.30%.同时采用红外光谱、NH3-TPD谱图、BET比表面和表面碱强度等分析手段对催化剂的性能进行了表征.  相似文献   

6.
目的以自制的复合无机盐Fe2(SO4)3.Na2S2O8为催化剂,氯乙酸和乙醇为原料合成氯乙酸乙酯.方法研究了氯乙酸与乙醇的摩尔比、催化剂用量、环己烷的用量、反应时间等因素对产品收率的影响,并用红外光谱(IR)、元素分析对产物氯乙酸乙酯进行了表征.结果与结论复合无机盐Fe2(SO4)3.Na2S2O8是合成氯乙酸乙酯的良好催化剂,适宜的反应条件如下:氯乙酸与乙醇的摩尔比为1∶2.0,催化剂用量为反应物总质量的2.5%,环己烷用量12 mL,反应时间1.5 h,氯乙酸乙酯的收率可达85.61%.  相似文献   

7.
采用微波辐射溶胶-凝胶法制备纳米级SO2-4/TiO2催化剂,以丙酸与正戊醇的酯化反应为探针反应,探究催化剂制备条件对催化活性的影响。并且采用Hammett指示剂法、BET法、XRD和TEM进行表征。结果表明,催化剂的最佳制备条件为乙酸12mL,无水乙醇10mL,去离子水4mL,微波辐射功率500 W。在常规加热条件下,当酸醇摩尔比为1∶1.3,催化剂用量为0.7g,反应时间为2h时,产率为98.11%。该方法制备得到的催化剂酸强度H0≤-13.16,为固体超强酸,催化剂比表面较大,其中TiO2为锐钛相,且分布比较分散。  相似文献   

8.
采用浸渍法制备多孔离子共聚物(PICP)负载的纳米Pd催化剂(Pd/PICP),考察Pd/PICP对苯酚选择性加氢反应的催化性能。通过透射电子显微镜(TEM)、X线衍射仪(XRD)和N2吸附-脱附分析仪等对催化剂进行表征,同时考察催化剂载体、反应溶剂和反应时间对苯酚加氢反应活性的影响。结果表明:Pd/PICP催化剂Pd颗粒粒径为2 nm左右,具有较大的比表面(635 m2/g)和孔体积(1.41 mL/g),在苯酚的还原反应中表现出较高的活性和选择性。在0.1 MPa H2下,n(Pd)∶n(苯酚)=1∶200,反应温度353 K,反应10 h,苯酚的转化率达到99%,环己酮的选择性达到97%,同时催化剂反复使用5次活性几乎没有降低。  相似文献   

9.
以ZSM - 5分子筛为载体用浸渍法混合负载Cu、Ce ,研制出一种复氧化物分子筛催化剂MxOy/ZSM - 5(Cu、Ce) .考察了它对液相合成乙酸丁酯反应的催化活性 ,并探讨了催化剂的制备条件对催化活性的影响 ,用IR、DTA、TG、ICP、比表面仪等技术对催化剂进行表征 .结果表明 :在Cu∶Ce =3∶1,T =12 0℃ ,酸∶醇 =1∶2 ,催化剂用量为 3g ,t =6h时 ,乙酸丁酯的产率高达 96 % ,且催化剂制备成本低 ,催化剂热稳定性好 .  相似文献   

10.
由于缺乏对废尾气催化剂的全面表征,导致对其物理化学性质及失效原因的了解不完全,影响其中铂族金属的回收。 为此,对报废尾气催化剂进行了化学组成和物相、表面元素、微观形貌、粒度、比表面积和热稳定性等一系列性质表征分析,得出其失效原因主要包括铂族金属硫化及磷化中毒、催化剂表面积碳吸附、铂族金属氧化、烧结团聚及铂族金属在载体内的包裹、比表面积和总孔体积缩小等。  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.
For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the  相似文献   

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