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1.
采用溶胶-凝胶技术分别将Keggin型和Dawson型杂多酸负载到TiO2载体上,制备了固体杂多酸催化剂H3PW12O40/TiO2、H4SiW12O40/TiO2和H6P2W18O62/TiO2,通过ICP-AES、31^P MAS NMR和N2吸附测定方法对其进行了表征,并对催化剂在合成乙酸乙酯反应中的催化性能进行了对比研究。实验结果表明,负载型杂多酸在反应中的活性高于母体杂多酸的直接催化。其中,H6P2W18O60/TiO2可在120min内使乙酸乙酯收率达到98%。  相似文献   

2.
纳米光催化材料H6P2W18O62/SiO2的制备与表征   总被引:2,自引:0,他引:2  
通过溶胶-凝胶技术将H6P2W18O62负载到载体SiO2上,制备了负载型光催化材料H6P2W18O62/SiO2。采用红外光谱(FT—IR)、电感耦合等离子原子发射光谱(ICP—AES)、固体核磁共振波谱(^31P MAS NMR)、N2吸附测定和透射电子显微镜(TEM)等手段,对该材料的组成、结构、表面物理性质和形貌进行了表征。结果表明,上述材料中具有光催化活性的H6P2W18O62仍保持着最初的Dawson结构。同时,该负载型光催化材料还具有纳米孔结构和较大的比表面积。  相似文献   

3.
光降解法制备聚苯胺纳米棒的研究   总被引:3,自引:3,他引:0  
采用高聚物聚乙烯醇(PVA)存在下的现场聚合法制备了可溶性的聚苯胺(PANI),并利用高压静电纺丝手段获得了PANI-PVA/TiO2的微米纤维毯.使用电子扫描电镜(SEM)、紫外-可见光谱、红外光谱等手段对样品进行了表征.以TiO2为催化剂,研究了PANI-PVA/TiO2微米纤维毯在254 nm光照射下的催化降解过程,同时探讨并给出了可能的光催化降解PVA的反应机理.结果表明,经过64 h的紫外光照射,PANI-PVA/TiO2中的PVA已基本分解,最终获得了PANI的纳米棒.  相似文献   

4.
采用溶胶-凝胶过程和静电纺丝技术,以三氯化铁(FeCl3·6H2O)、醋酸钴(Co(CH3COO)2·4H2O)和聚乙烯醇(PVA)为前驱物,制得PVA/FeCl3/Co(CH3COO)2复合纳米纤维.经高温煅烧,制备了CoFe2O4纳米纤维.利用扫描电镜(SEM)、红外光谱(FT-IR)、差热-热重(TG-DTA)和X射线衍射(XRD)等分析测试手段对样品进行了表征,并研究了其磁性质.结果表明:静电纺丝技术制备的CoFe2O4纳米纤维为规则的一维结构,直径分布均匀,具有良好的铁磁性.  相似文献   

5.
在模板剂P123作用下,采用溶胶一凝胶再结合程序升温溶剂热法制备了光催化材料H6P2W18O62/TiO2(P123)和H3PW12O40/TiO2(P123),通过FTr—IR、ICP—AES、XRD、N2吸附一脱附等检测手段对其组成、结构及其表面物理化学性质进行了表征。结果表明,合成材料晶型结构良好,母体多酸的基本结构未发生明显变化,孔径分布均匀,经P123处理的合成产物H6P2W18O62/TiO2(P123)比表面积高达414.6m2/g。  相似文献   

6.
采用可以食用的玉米淀粉糖为原料,用乙醇做溶剂,通过高压静电纺丝法制备了玉米淀粉糖的超细纤维.经加热处理增加了玉米淀粉糖超细纤维的稳定程度和柔韧性,并降低了水溶性.通过X射线粉末衍射(XRD)、红外光谱(IR)和扫描电子显微镜(SEM)等测试手段对纤维的组成和形貌进行了表征.结果表明,玉米淀粉糖与乙醇发生了缩醛化反应.  相似文献   

7.
以聚乙烯吡咯酮(PVP)为络合剂,Dy(NO3)3·6H2O和Eu(NO3)3·6H2O反应制得前驱体溶液,用静电纺丝法制备了PVP/Dy(NO3)3·Eu(NO3)3无机-有机复合纤维,经煅烧得到Dy2O3/Eu3+微纳米纤维.对所制备纤维分别采用差热-热重分析、红外光谱分析、X射线衍射分析、扫描电镜等手段进行表征.  相似文献   

8.
采用聚丙烯腈/N,N-二甲基甲酰胺/多氨基超支化聚合物三元体系为纺丝液,通过静电纺丝制备了PAN/HBP复合超细纤维,探讨了聚丙烯腈浓度、超支化聚合物含量、纺丝电压、接收距离和推进速度等因素对复合纤维直径和形貌的影响.结果表明,增大PAN浓度和增加HBP含量,都会使纤维直径增大;静电纺丝电压增大,可以减小纤维直径;适当的接收距离和推进速度才可以获得直径细而均匀的纤维.通过对PAN/HBP复合超细纤维的氨基含量测试和FTIR分析,进一步证实了PAN/HBP复合纤维表面和内部氨基的存在.  相似文献   

9.
采用静电纺丝技术制备不同晶体结构的Nb2O5纳米纤维,利用SEM和XRD技术对产物的形貌和结构进行表征.结果表明:所得Nb2O5纳米纤维晶化良好、尺寸分布均匀、长径比高且连续性好.通过调整静电纺丝的电压,可对纳米纤维的直径进行调控.调整退火温度和退火气氛,可分别获得伪六方、正交、单斜和正交/单斜混合相的纳米纤维.  相似文献   

10.
采用溶胶-凝胶技术将光催化剂H6P2W18O62负载到载体SiO2上,制备了负载型纳米光催化材料H6P2W18O62/SiO2。通过对四种染料的吸附实验,确定了光催化反应的模型分子。研究了该纳米材料对可溶性染料茜素红的光催化活性。结果表明,上述材料在8h的太阳光作用下,对茜素红的脱色率达98%以上。另外,负载后的光催化剂易分离、回收,可循环使用。  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.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

13.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

14.
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   

15.
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   

16.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

17.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

18.
19.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

20.
Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with  相似文献   

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