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1.
使用碱处理脱硅法制备了含介孔ZSM-5沸石催化剂.碱处理温度越高、时间越长,在ZSM-5沸石中引入介孔越多.在该低硅ZSM-5沸石改性过程中观察到脱硅过程中伴随脱铝现象,表现为在介孔大量生成的同时,沸石硅铝比仅小幅下降,且NH3-TPD测试表明酸性位数量明显下降.该微介孔ZSM-5沸石催化剂被应用于甲醇制丙烯(MTP)反应中并展现出良好的催化稳定性.  相似文献   

2.
本文研究的是在425℃、常压下,通过粘结沸石催化剂,甲醇与氨选择性合成一甲胺的反应。发现ZSM-5及ADHM沸石催化剂对一甲胺的选择率大于88%,甲醇转化率为90%以上。对三甲胺表现出明显的抑制效应可归结于沸石的择形催化效应。  相似文献   

3.
以粗孔硅胶与NaAlO_2为源料,TPABr为模板剂,用水热晶化法合成ZSM-5小颗粒团聚体.用XRD、SEM、NH_3-TPD、N_2物理吸附、XRF及TG等方法对其结构进行表征,并考察其甲醇制丙烯(MTP)反应的催化性能.与文献制备的样品相比,制备的ZSM-5小颗粒团聚体含有更丰富的介孔和更好的抗积碳性能,在MTP反应中表现出更好的丙烯选择性和稳定性,其丙烯平均选择性为47.27%,单程寿命达310h.  相似文献   

4.
通过浸渍法制备了磷改性的高硅ZSM-5球形催化剂.采用XRD,BET,NH3-TPD等手段对催化剂进行了表征.结果表明,磷化合物均匀地负载在催化剂表面,且进入了分子筛晶内孔道,磷的引入对分子筛骨架没有明显影响,但会导致孔道内表面脱铝,磷修饰后催化剂强酸中心明显消失,弱酸位有所增加.磷修饰高硅ZSM-5催化剂的甲醇转化反应结果表明,高硅ZSM-5催化剂内的磷化合物可以有效地抑制氢转移反应,但对重组分影响较小,磷引入后丙烯选择性明显增加但甲醇转化率下降,过量负载的磷化合物导致催化剂活性迅速降低.  相似文献   

5.
将一系列自制天然丝光沸石催化剂与目前国内唯一工业化的A-6催化剂及氢型合成丝光沸石催化剂进行比较,筛选出催化效果较好的催化剂NaHM,并对其进行工艺条件优化,同时考察了NaHM用于甲胺合成反应的稳定性。结果表明天然丝光沸石催化刑具有更好的二甲胺选择性;金属离子改进可强化沸石的择形效果,但同时降低甲醇转化率。改性催化剂中NaHM效果最好。该催化剂具有较好的活性稳定性,适宜的工艺条件为:t=390℃、τ(LHSV)=1.93h^-1、n(N)/n(C)=1.8。此时其甲醇转化率为93.9%,二甲胺选择性为38.5%。  相似文献   

6.
本文为综合利用低碳醇类以扩大芳烃来源探索了新的途径。我们参照Mobil公司新介绍的方法原理,利用微型催化反应装置,研究了ZSM-5沸石催化剂的制备条件对低碳醇类芳构化催化活性的影响,以及反应条件对反应产物分布的效应,并对低碳醇类在ZSM-5沸石催化剂上的芳构化过程作了初步探讨。试验结果表明:在反应温度370—400℃,体积空速为3.0~4.5hr~(-1)时,异丙醇在HZSM-5沸石催化剂上芳烃的收率较高。约为16%~25%(重)。  相似文献   

7.
本文用CaO对ZSM-5沸石进行改性,在丙烯的芳构化反应和甲苯的甲基化反应中,其对二甲苯选择性与未改性前相比,可得到很大的提高,同时应用分子筛窗口模型,计算了用CaO改性前后的ZSM-5沸石:对于甲苯分子中各碳原子的电荷密度的影响,从而解释氧化物改性使ZSM-5沸石对二甲苯选择性提高的原因。我们认为其原因主要不是沸石孔径的变化,而是由于改性后对反应物分子电荷分布产生的影响,也即改变了沸石表面酸性的结果。  相似文献   

8.
本文研究了在甲醇与甲苯侧链的烷基化反应中,K_2B_4O_7(Ⅰ)与H_3BO_3-MgO(Ⅱ)对X型沸石催化剂的改性规律。用Ⅰ对KX沸石进行改性,当每100gKX沸石含3.12×10~(-2)mol K_2B_4O_7时,甲醇的选择性较好;用Ⅱ进行改性,每100gKX沸石含0.8mol MgO及0.19mol H_3BO_3时,产品中苯乙烯的含量及苯乙烯与乙苯的产率都较高。当采用H_3BO_3-MgO-Cs X型催化剂时,甲醇转化率和选择性分别达到88%及27%,苯乙烯及乙苯的产率达到0.63(g/gCat·h)。同时对X型沸石催化剂失活进行了研究,认为除了结焦导致失活外,反应过程中产生的水蒸汽使沸石的结构和性能受到破坏,亦导致失活。  相似文献   

9.
本文对H3BO3和KOH酸碱双组分浸渍或机械混合法改性的KX沸石进行了甲苯与甲醇侧链烷基化反应的系统研究。结果表明,采用H3BO3和KOH双组分改性的KX沸石比只用KOH或H3BO3单一组分改性的KX沸石反应性能好,而且中等交换度的KX沸石经H3BO3和KOH改性后,苯乙烯(ST)和乙苯(EB)的选择性和 ST/(ST EB)比值提高的最为显著。在反应温度为430℃。W/F=50(g·h/mol),N2/F=5(mol比)、甲苯与甲醇的mol比为5的反应条件下,交换度为57%的KX沸石浸渍5% 的H3BO3和与H3BO3等mol比的KOH后得到的改性沸石催化剂的反应结果如下:选择性为,30%,ST…  相似文献   

10.
为筛选丙烯二聚催化剂,探讨丙烯二聚反应的活性中心及反应机理,制备了一系列Zn或Zn-Mg、Zn-Ni双组分改性ZSM-5沸石催化剂,采用IR、NH3-TPD研究了其表面酸性,用脉冲微反技术评价了它们的丙烯转化活性和二聚选择性。结果表明:在指定反应条件下,Zn-Mg/NH4-ZSM-5(IM)样品的丙烯转化率达94.2%,二聚选择性近100%。在此样品上丙烯二聚按正碳离子机理进行,其活性中心是B酸中  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.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

13.
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   

14.
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   

15.
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   

16.
17.
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   

18.
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   

19.
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   

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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