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1.
讨论了DTA图谱(差热图谱)中峰的起点、顶点、结束点、峰面积、重叠峰的意义以及峰形所揭示的某些反应动力学意义;阐述了DTA图谱的解析方法,在一定实验条件下可以定性确定样品在实验温度范围内是否产生热效应,以及产生热效应的起始温度和相对热效应的大小。  相似文献   

2.
本文用国产的高压差热分析仪评价了五种铁催化剂对云南小龙潭煤加氢反应的催化活性。发现FeS和天然硫铁矿有良好的催化效果,而Fe_2O_3和含Fe_2O_3的工业废渣——太钢转炉飞灰的催化效果不明显。说明铁催化剂只有在以硫化物状态存在时,对煤加氢反应才呈现出较好的催化活性。予硫化后催化剂活性得到提高的事实进一步证明了这一结论。根据Freeman-Carrol法计算了Fe_2O_3、FeS太钢转炉飞灰、予硫化后的太铁转炉飞灰作催化剂时小龙潭煤加氢反应的动力学参数。同时用Speil公式计算了这些反应的热效应,建立了热效应与DTA峰前温度和峰后温度下反应产物中组分变化之间的关系。  相似文献   

3.
为给镍钼矿的选-冶结合提供理论依据,通过对镍钼矿原矿与在800℃中性焙烧1.5 h后镍钼矿进行X线衍射(XRD)分析;在空气气氛与氩气气氛中对镍钼矿进行差热与热重分析,并对原矿和焙烧预处理矿进行浮选实验.研究结果表明:在300~800℃,有氧参与的空气气氛中,镍钼矿中有机质不断燃烧,差热分析(DTA)曲线产生很大的放热峰,质量损失率达20%;而在氩气气氛中,主要发生挥发、硫化、化合等反应,放热峰很小,质量损失率为18%;当温度高于800℃时,空气气氛中一直发生分解反应;而氩气气氛中,当温度超过1 320℃时,分解反应完成,开始出现化合反应;焙烧预处理后的镍钼矿更易于浮选,精矿钼品位提高0.88%,回收率提高7.91%.  相似文献   

4.
采用文题技术,建立了一个微量、快速的方法,用于评选稀丙烯氧化制丙烯醛的催化剂(Co-Fe-Bi-Mo-A-B-C-O)的焙烧条件。结果表明:对复杂的选择性催化氧化反应,DTA峰值并不一定与转化率有对应关系,不能直接用来作评选活性的依据。但根据DTA出峰时,截取其反应逸出气体进行GC分析,从测到的DTA峰高和丙烯醛峰面积,则可得到焙烧条件与活性和选择性之间的对应关系,从而获得最佳焙烧条件。结果得到实验室评价装置的验证。  相似文献   

5.
由于生物质燃料放热反应太快,直接应用在烧结中导致火焰前峰与热波前峰不匹配影响烧结矿性能.因此,利用CaO粉末对生物质燃料孔隙进行填充和生物质燃料“包裹制粒”对生物质燃料改性,并利用差热实验和热重实验对改性后燃料和焦煤进行对比检测实验.结果表明:生物质燃料经CaO粉末改性后,生物质燃料放热开始反应温度Te提升至382.09℃,放热拐点温度Ti提高至395.23℃,差热曲线(DTA)后移延缓热量释放;改性生物质燃料经包裹制粒后,开始失重温度提高至462℃,放热时间明显延长,与焦粉失重曲线接近.  相似文献   

6.
用自行改造组装的多气氛高压高温差热分析装置研究了平鲁煤焦的水蒸气加压气化动力学。水蒸气分压为0.01,0.03,0.11和0.33MPa,最高反应温度为1450K.实验结果表明,反应温度对气化速率有显著影响;水蒸气分压对气化速率在低压时有明显影响;气化反应的活化能随转化率变化。与实验值基本吻合的计算值表明虑及压力和孔结构变化的动力学方程可以较好地描述平鲁煤焦在加压水蒸气中的气化行为。整个工作还表明,DTA技术也是研究煤气化动力学的一种有效手段。  相似文献   

7.
含石蜡燃料热分解特性研究   总被引:1,自引:0,他引:1  
胡松启  王鹏飞 《科学技术与工程》2013,13(11):3209-3212,3220
采用差示扫描量热法(DSC)和热重法(TGA)对HTPB燃料、石蜡及含石蜡燃料的热分解过程进行了分析。研究了石蜡含量、碳粉含量和不同升温速率对含石蜡燃料热分解过程的影响。实验结果表明:石蜡热分解过程可以分为低温分解阶段和高温分解阶段。含石蜡燃料的热分解主要分为四个阶段;随着石蜡含量的增加,样品的初始分解反应放热峰温和第三反应放热峰温不断提前,放热量不断增大,而对其第二分解放热峰和镁粉氧化放热峰基本无影响;随着升温速率的增大,含石蜡燃料各分解反应的放热峰温不断提高,第二、第三分解反应的放热量增大;计算出了4#含石蜡燃料的第一、第二、第三热分解反应的活化能E和指前因子A。  相似文献   

8.
MA/AA无皂乳液聚合改性纳米SiO_2   总被引:1,自引:0,他引:1  
以α-甲基丙烯酸、丙烯酸为反应单体,对纳米SiO2进行无皂乳液聚合表面改性;采用正交试验法探讨了反应温度、反应时间、原材料配比反应条件对纳米SiO2粒子表面改性反应的影响,并对改性前后的纳米粒子进行了红外光谱(IR)分析和差热分析(DTA). 研究结果表明,较佳的改性聚合反应条件为反应温度80 ℃、反应时间3 h、原材料配比(单体与纳米SiO2质量比)为3:100,在此条件下进行改性反应改性效果明显.  相似文献   

9.
本工作利用差热(DTA)—热重(TG)法研究了催化剂表面积炭的清除问题,提出一种测定积炭的方法,并对失活工业催化剂r—Al_2O_3的表面积炭进行了测定;根据DTA—TG谱图对催化剂的再生条件的选择作了讨论,建议DTA谱图的差热峰在(d▽T)/(dt)=0时的温度宜为再生温度。  相似文献   

10.
研究了在氧气存在下生物质催化氧化制甲酸体系中甲酸的稳定性,主要考察了反应温度、反应时间、氧气初始压力、硫酸浓度、催化剂等因素对于甲酸分解的影响。研究结果表明,温度、反应时间、硫酸浓度对甲酸的分解速率有显著的影响;氧气的初始压力对于甲酸的分解影响较小;催化剂NaVO3的存在会加速甲酸的分解。生物质催化氧化体系中,甲酸的分解反应为二级反应,甲酸分解反应的表观活化能为85.1 k J/mol。提出了在H2SO4溶液中氧气气氛下NaVO3催化甲酸分解的机理。  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.
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   

14.
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   

15.
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   

16.
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   

17.
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   

18.
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   

19.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

20.
The non-orthogonal localized molecular orbital(NOLMO)is the most localized representation of electronic degrees of freedom.As such,NOLMOs are thus potentially the most efficient for linear scaling calculations of electronic structures for large systems.However,direct ab initio calculations with NOLMO have not been fully implemented and widely used,partly because of the slow convergence issue in the optimization of NOLMO.We devel-  相似文献   

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