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1.
合成了3种新颖具有轴手性多氢键多活性中心的双硫脲催化剂(1a~1c),并将其应用于催化PictetSpengler反应合成β-咔啉类化合物.实验结果表明,在室温(25℃)下,甲苯为溶剂,催化剂1c的用量为x=20%,Pictet-Spengler环化反应取得较高的收率(82%)和较高的对映选择(88%).  相似文献   

2.
S2O82-/ZrO2-MxOy(M=Al,Fe,Cr,Mn,Ti)固体超强酸催化剂的研制   总被引:1,自引:2,他引:1  
制备了一系列金属氧化物MxOy(M=Al,Fe,Cr,Mn,Ti)促进的S2O8^2-/ZrO2-MxOy固体超强酸催化剂,用乙酸和正丁醇的酯化反应研究了制备条件对催化剂活性的影响,实验结果表明,催化剂对酯化反应有很高的催化活性,添加不同的金属氧化物对催化剂的酯化反应催化活性有不同的影响,其中Cr含量为0.5%的催化剂S2O8^2-/ZrO2-Cr2O3对乙酸和正丁醇的酯化反应具有很高的催化活性,乙酸的转化率高达86.1%,而在相同条件下,不加催化剂时乙酸的转化率仅为26.9%,制备条件对催化剂活性影响很大,通过X射线衍射分析(XRD)证实,催化剂中ZrO2主要以四方晶相(Tetragonal phase)存在,少量以单斜晶相(Monoclinic phase)存在,T相和S2O8^2-是保证催化剂活性的关键因素。  相似文献   

3.
对以活性碳负载磷钨杂多酸为催化剂,巯基乙酸为助催化剂,苯酚和苯甲醛为原料,催化合成双(4-羟基苯基)苯基甲羟的反应进行了研究。试验发现,磷钨杂多酸的活性碳负载量为50%时,催化活性最好。通过对缩合反应的正交试验表明,活性碳负载磷钨杂多酸的负载量、主催化剂用量、助催化剂用量、酚醛物质的量比、反应的温度及反应的时间对缩合反应的收率有影响。反应的最佳条件为:活性碳负载磷钨杂多酸的负载量为50%,n(酚)/n(醛)=4∶1,反应温度100℃,主催化剂2.5g,助催化剂0.1mL,反应时间2h,收率可达73.8%。  相似文献   

4.
对碳酸二甲酯与环己胺化合生成N-环己基氨基甲酸甲酯的反应进行了研究.考察了催化剂BF3的催化活性和相关反应条件.控制反应的较佳参数为:催化剂用量为n(环己胺):n(BF3)=20:1;反应回流时间为20 h;反应温度控制在70℃;反应物配比n(DMC):n(环己胺)=1.5:1.最高产率为49.05%,且反应后处理简单,对环境污染少.产品纯度高,达99.94%.  相似文献   

5.
蜂窝状筛网催化剂上NH3选择性催化还原NO的动力学   总被引:4,自引:0,他引:4  
将蜂窝状筛网催化剂应用于以NH3为还原剂选择性催化还原(SCR)NO的反应中。蜂窝状筛网催化剂的高开孔结构,使其较粉末催化剂具有较低的压力降,较蜂窝状堇青石催化剂具有较高的传质系数。对峰窝状筛网催化剂进行了活性考察,同时与粉末催化剂、蜂窝状堇青石催化剂的活性加以对比,并进行了反应动力学行为的分析。结果表明:蜂窝状筛网催化剂在低温下(T<493K),反应主要受化学动力学控制,传质系数随温度的升高而增加;高温下(T>513K),反应受传质控制,此时蜂窝状筛网催化剂(传质系数的平均值为8.13s^-1)较蜂窝状堇青石催化剂(传质系数的平均值为5.14s^-1)具有更高的传质系数。  相似文献   

6.
活性炭负载SiW12杂多酸催化合成乙酸异丙酯   总被引:1,自引:0,他引:1  
为研究SiW12/C催化剂对丙烯与乙酸酯化反应的催化性能,采用浸渍法制备了一种负载硅钨杂多酸(H3SiW12O40)的活性炭(SiW12/C)催化剂.采用固定床装置由乙酸和丙烯直接酯化合成乙酸异丙酯.合成实验的最优反应条件:烯酸物质的量比为3:1,反应温度为120℃,SiW12(30%)/C催化剂用量为5 g,反应压力为0.8 MPa,体积空速为(LHSV)1 h-1.乙酸转化率可达82.1%.分析证明,SiW12/C催化剂具有转化率高、条件温和、选择性好等优点,是催化酸酯化反应的高活性催化剂.  相似文献   

7.
固载杂多酸催化合成乳酸正丁酯   总被引:6,自引:0,他引:6  
用固载杂多酸PW12/SiO2为催化剂,实现了乳酸与正丁醇反应合成乳酸正丁酯,最佳合成条件为:n(酸):n(醇)=1:3.0,催化剂用量为乳酸质量的5%,反应时间为2h,产率可达92%,催化剂具有容易回收并可循环使用不污染环境等优点。  相似文献   

8.
一缩二乙二醇二苯甲酸酯的合成   总被引:1,自引:0,他引:1  
用自制的高分子固载化螯合钛酸酯催化合成一缩二乙二醇(俗称二甘醇)二苯甲酸酯(DEDB)。通过试验确定了合成DEDB的适宜的工艺条件为:n(一缩二乙二醇):n(苯甲酸)=1.0:2.1,催化剂用量为0.41%,反应时间3h,反应温度210℃,产率达96.5%。催化剂的催化活性高,易与产品酯分离,可重复使用。  相似文献   

9.
用固体酸五氧化二铌作酯化催化剂,由苯酐和2-乙基己醇制备了邻苯二甲酸二(2-乙基己)(DOP)。反应先快速生成了中间产物邻苯二甲酸单(2-乙基己酯)然后再酯化双酯DOP。由单酯转化成双酯的反应为典型的二级反应,测定了二级反应的速率常数和活化能,研究了催化剂的循环使用,探讨了反应时间,反应温度和催化剂用量等因素以粗产品酸度和外观质量的影响。  相似文献   

10.
研究了以水为溶剂,三乙基苄基氯化胺(TEBA)为催化剂,对溴甲苯为原料,高锰酸钾为氧化剂,在酸性和碱性条件下合成对溴苯甲酸的反应.考察了催化剂用量、反应物摩尔比、反应温度、反应时间等对反应的影响.最优条件为:以水为溶剂,n(对溴甲苯)∶n(KMnO4)∶n(Na2CO3)为1.0∶2.5∶1.0,TEBA(5%)为催化...  相似文献   

11.
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   

12.
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   

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

14.
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   

15.
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   

16.
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   

17.
18.
The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.  相似文献   

19.
R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).  相似文献   

20.
The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.  相似文献   

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