首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 109 毫秒
1.
使用共沉淀-浸渍法制备介孔钨锆复合氧化物。通过X线衍射(XRD)、NH_3程序升温脱附(NH_3-TPD)、透射电子显微镜(TEM)和N_2物理吸附-脱附等方法对介孔钨锆复合氧化物进行表征。通过连续流动的固定床反应器考察钨锆复合氧化物载铂催化剂对甘油氢解反应的催化性能。结果表明:与商业Zr(OH)_4制备的钨锆复合氧化物相比,由共沉淀法制得的Zr(OH)_4制备的钨锆复合氧化物具有最大的总酸量和最多的弱酸含量。并且由共沉淀-浸渍法制备的介孔钨锆复合氧化物颗粒团聚现象较少,更加疏松分散,具有最大的介孔(17. 8 nm)、最小的平均粒径(9. 3 nm)和最大的比表面积(87 m~2/g),其在负载铂后对甘油氢解反应的活性也最高。  相似文献   

2.
以聚乙二醇(PEG)为模板剂、正硅酸乙酯(TEOS)为硅源,采用溶胶-凝胶法合成了铜掺杂介孔硅铝氧化物复合材料,并通过N2等温吸附-脱附法、X射线衍射、红外光谱等测试对产物进行表征,考察了PEG质量、分子量以及CuO掺杂量对复合材料孔结构的影响.结果表明:加入PEG能够明显增加复合材料的比表面积,随PEG质量增大,介孔孔容增多,孔径分布较均匀,加入24 g PEG时比表面积增加一倍达到约500 m2.g-1.PEG的分子量为600~2 000时样品以4 nm介孔为主,而分子量为10 000时,样品以小于2 nm的微孔为主.  相似文献   

3.
使用水热合成法,以十六烷基三甲基溴化铵(CTAB)为模板剂,ZrOCl_2·8H_2O为锆源,水为溶剂,在碱性条件下成功地制备出介孔SO■/ZrO_2.通过傅里叶红外光谱分析(FTIR),N_2物理吸脱附(BET),透射电镜(TEM), X射线衍射(XRD),氨程序升温脱附(NH_3-TPD)手段对其结构进行了表征.结果发现,550℃煅烧后样品的比表面积为179 m~2/g,平均孔径为4.1 nm;TEM显示样品的孔道呈蠕虫状;NH_3-TPD表征发现该催化剂具有超强酸性.该催化剂用于煎炸废油甲酯化反应中生物柴油的制备,具有较高的活性,在200℃下反应6 h后的收率能达91%以上.  相似文献   

4.
采用真空浸渍法制备了一系列修饰有ZrO_2的介孔Al_2O_3负载的CoCu双金属介孔纳米复合催化剂.对催化剂进行了X射线衍射(XRD)、N_2吸脱附实验(BET)和H_2-程序升温还原表征(H_2-TPR),系统考察了催化剂的物相结构、比表面积、孔结构以及H_2还原性能.并将催化剂用于合成气制备低碳醇的反应中,发现此催化剂具备良好的CO加氢活性和低碳醇选择性,这主要是由于催化剂具有高比表面积、适宜的孔分布以及高分散的活性组分.  相似文献   

5.
采用有机模板剂去除法制备介孔La-Co-Ce-O系复合氧化物,研究溶液体系的pH值及模板剂十六烷基三甲基溴化铵(CTAB)浓度对晶态和孔径结构影响;对制备的样品采用XRD测试和N2吸脱附方法表征其晶态结构和孔径结构。研究结果表明:该介孔氧化物具有较高的比表面积(高达160m2/g)和均匀的孔径;当pH值和CTAB浓度变化时,实现介孔La-Co-Ce-O系复合氧化物的孔径在3.0~21.0nm之间可调;制备条件的变化对介孔氧化物样品的晶态结构稍有影响。  相似文献   

6.
采用聚合物P123为模板剂、正硅酸乙酯为硅源水热成功合成了具有介孔、二维六角结构的SBA-15,并以SBA-15为硬模板、蔗糖为碳源合成了具有有序介孔结构的CMK-3碳材料.将CMK-3浸渍于硝酸亚铈溶液中,经过干燥、焙烧,制备出了具有二维六角结构的二氧化铈材料.利用N2物理吸附、X光粉末衍射(XRD)、透射电镜(TEM)对所得材料进行了物化性质测试与结构表征.结果表明,合成的二氧化铈具有面心立方结构,呈现IV型吸-脱附等温线及H3型滞后环,孔径分布均一,平均孔径3.3 nm,其比表面积达104.2 m2/g.  相似文献   

7.
模板剂对介孔碳孔道结构及有序性的影响   总被引:2,自引:0,他引:2  
分别以三嵌段聚合物F127、P123以及P123/F127作为模板剂,酚醛树脂为有机碳源,采用溶剂挥发自组装法制备有序介孔碳材料。采用XRD,TEM和N2吸/脱附等手段对有序介孔碳进行表征,研究F127、P123及P123/F127复合模板剂对介孔碳孔道结构及有序性的影响。结果表明,使用单一模板剂时,F127较P123更易产生有序六方介孔结构;使用P123/F127复合模板剂,介孔碳有较好的二维六方有序性,介孔孔容和比表面积较单独使用F127作模板分别提高了50%与31%;当m(P123)/m(F127)=1/3时,所得介孔碳BET比表面积为498.5 m2/g,介孔孔容和比表面积分别为0.173 cm3/g和167m2/g,平均孔径为3.41 nm。  相似文献   

8.
在十二烷基三甲基溴化铵(CTAB)的辅助下,利用水热法制备了WO3/ZrO2复合氧化物纳米样品,利用XRD、TEM、SAED、N2吸附-脱附等方法对样品的形貌、结构、孔径进行了表征.结果表明:氧化钨被氧化锆包覆煅烧后,团聚成网状结构的纳米粒子,其BET表面积为368m2/g,平均孔径为5.29nm,孔分布不均匀,无序程度极高.  相似文献   

9.
以硝酸锆为锆源,以阴离子表面活性剂十二烷基硫酸钠(SDS)为模板剂,S2O8^2-浸渍无定形Zr(OH)4,制得介孔S2O8^2-/ZrO2固体超强酸,通过N2吸附-脱附、XRD分析、Hammett非水滴定、TEM等方法,考察了不同焙烧温度对S2O8^2-/ZrO2介孔超强酸晶体结构、酸强度等性能的影响。结果表明,当焙烧温度600℃,S2O8^2-/ZrO2样品比表面积为140m2/g,平均孔径在3~4nm之间,酸强度H0≤-12.7,为介孔相固体超强酸。  相似文献   

10.
以硝酸铬和硝酸铈作金属源、用介孔氧化硅作硬模板,通过真空辅助浸渍法制备得到高比表面积有序介孔Cr2O3-Ce O2复合氧化物,采用XRD、TEM、UV-Vis和N2吸附-脱附技术表征了样品的物理化学性质.结果表明,经过500℃灼烧处理的样品(meso-Cr-Ce)孔壁晶化度高且虫孔结构发达,比表面积达160 m2/g,平均孔径为7.2 nm,在紫外和可见光区还具有优良的吸光性能.这些特性将使该材料在催化领域特别是光催化领域有着广阔的应用前景.  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 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   

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.
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   

15.
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   

16.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

17.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

18.
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   

19.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

20.
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   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号