Sm修饰的Ni-MgO催化剂制备碳纳米管的研究

Carbon nanotubes (CNTs) have been synthesized over Ni-MgO and Ni-Sm-MgO catalysts by decomposition of CH₄ at 650 ℃. The addition of Sm into Ni-MgO catalyst not only promotes the catalytic activity and lifetime of the catalyst, but also improves the graphitization and heat stability of carbon nanotubes. The yield of CNTs obtained over the Ni-10Sm-MgO catalyst reaches 33 g C·(g Ni)^-1, being more than 5 times higher than that of the Ni-MgO catalyst. XRD and TPR results of the catalysts indicate that there is a remarkable interaction of Ni with Sm species, which facilitates the reduction of nickel and restrains the Ni particles from agglomerating.     

低温催化裂解烷烃法制备碳纳米管

低温催化裂解烷烃法制备碳纳米管陈萍，王培峰，林国栋，张鸿斌，蔡启瑞（厦门大学化学系固体表面物理化学国家重点实验室，厦门，３６１００５）关键词碳纳米管，催化裂解，甲烷碳纳米管的制备与研究是国际上新材料领域的探索热点［１］．由于具有纳米级的管径，碳纳米管...     

催化裂解CH4制备不同形貌的碳纳米管

通过甲烷于较低温度(500～700℃)下在镍催化剂上催化裂解制备了各种形貌的碳纳米管.透射电镜测试结果表明,碳纳米管的外径和内径明显地受催化剂的大小和形貌的影响.本文考察了催化剂前驱体的种类、反应温度和原料气流速对镍催化剂和碳纳米管形貌的影响.     

催化裂解CH4制备碳纳米管的影响因素

以柠檬酸法制备的Fe-MgO、Co-MgO和Ni-MgO为催化剂,CH4为碳源气,H2为还原气,在873、973和1073 K制备出碳纳米管,通过TEM和拉曼光谱表征,讨论了催化剂、制备温度、反应时间等因素对碳纳米管形貌、产率和内部结构的影响.结果表明:不同的催化剂在相同的温度下制备的碳纳米管的形态和内部结构有很大的差异.其中Fe-MgO催化剂制备的碳纳米管管径粗,且大小不均匀,而Ni-MgO催化剂制备的碳纳米管管径较细、较均匀.碳纳米管的产率随着裂解温度的变化而改变.Fe-MgO催化剂制备碳纳米管的产率随制备温度的升高而提高,而Ni-MgO催化剂制备碳纳米管的产率随制备温度的升高而降低.Fe-MgO催化剂制备碳纳米管,在1073K甚至更高的制备温度才能达到其最高产率.Co-MgO催化剂制备碳纳米管的产率在973 K左右产率较高,而用Ni-MgO催化剂制备碳纳米管,则在873 K甚至更低的制备温度就能达到最高产率.反应时间与碳纳米管的产率不成正比,有一最佳反应时间,如Ni-MgO催化剂的最佳反应时间为2 h.     

催化剂制备条件对碳纳米管的影响

用柠檬酸络合法制备的Ni-La-Mg型催化剂催化裂解甲烷合成碳纳米管，并通过测定活性镍表面积研究了催化剂制备过程中柠檬酸浓度及活化温度对碳纳米管生成的影响，TEM测定结果表明，经凝胶自燃烧产生的催化剂，可通过改变柠檬酸的浓度来制得不同粒径的催化剂颗粒，从而获得一定管径的碳纳米管，另外，在500－700℃内，活化温度对催化剂活性影响不大，只有在较低或较高温度时对活性才有较大的影响。     

催化裂解低碳烷烃制备碳纳米管薄膜

碳纳米管性质奇特、用途广泛[1]。目前制备碳纳米管薄膜的方法主要有电弧放电法[2]、催化裂解[3]、及真空过滤碳纳米管悬浮液制备“巴基管纸”(Buckypaper)[4]等。本文采用镀镍基板催化裂解低碳烷烃法制备碳纳米管薄膜,考察了镀膜时间、蚀刻和氨水处理等条件对碳纳米管薄膜产物形貌的影响。1　实验部份1 1　镀膜与后处理采用离子溅射法在硅酸盐基板上镀镍,镀镍电流7 5mA,镀镍时间分别为2min、15min、30min、45min或60min;对镀镍基板再进行蚀刻(蚀刻电流7 5mA,蚀刻时间2min)或用氨水浸泡处理(含NH325%,超声振荡30min),然后烘干备用。1 …     

分叉碳纳米管的催化生长

Branching carbon nanotubes were synthesized by pyrolysis of acetylene at 700℃ over oxygen-free copper and γ-Al₂O₃-supported Cu unitary or Cu/Fe binary catalysts. The morphologies of the as-grown products were charac-terized by transmission electron microscopy. The results indicated that the branching structures were closely related to the Cu component of the catalysts. We proposed that the special electronic structure (3d¹⁰4s¹) of Cu play the crucial role in the formation of the heptagon defects related to the branching structures.     

单壁碳纳米管自还原法制备负载Pt催化剂及其催化性能

金属Pt是良好的催化加氢、脱氢催化剂, 利用单壁碳纳米管(SWNTs)自身的还原性, 将K2PtCl6溶液中的Pt直接还原并负载在SWNTs表面上, 制备了具有良好催化性能的SWNTs/Pt负载型催化剂. 通过TEM, XPS和TG对材料进行了表征, 研究了K2PtCl6浓度及溶剂对Pt负载量、粒径的影响, 并测试了SWNTs/Pt的催化性能. 实验结果表明, SWNTs负载的Pt颗粒小, 分散均匀, 负载量高, 与SWNTs结合紧密, 催化性能好, 是催化加氢和脱氢反应的良好催化剂.     

柠檬酸用量对碳纳米管制备的影响

Carbon nanotubes (CNTs) were prepared by chemical vapor catalytic deposition using the catalyst prepared by citric acid complexometry. The effect of the dosage of citric acid on the CNTs yield and morphologywas studied. The transmission electron microscopy and X-ray diffraction were used to characterize CNTs morphology and crystal structures of the catalysts, respectively. The results show that the dosage of citric acid can greatly affect the CNTs yield and morphology: the CNTs have a high yield about 1 345.8% (1 h) at a 2∶1 molar ratio of citric acid and metal ion, and the obtained CNTs diameter is relatively narrow distributed (25～30 nm); when themolar ratio of citric acidto metal ion is 3∶1, the CNTs yield is about 407.2% (1 h), and the obtained CNTs diameter is relatively wide distributed (25～50 nm), moreover, the CNTs is more rough than that obtained with 2∶1 molar ratio of citric acid to metal ion.     

碳纳米管/FeS类Fenton催化剂的制备及催化性能

以浮动催化热分解法制备碳纳米管(CNTs), 采用氧化-还原-硫化的方法制备了CNTs/FeS催化剂, 采用X射线衍射(XRD)、 透射电子显微镜(TEM)和热重(TG)分析等技术对催化剂进行了结构表征. 将CNTs/FeS作为类Fenton催化剂用于水中环丙沙星的去除, 研究了降解过程中H₂O₂浓度、 CNTs/FeS催化剂的投加量、 环丙沙星浓度及pH等因素对催化降解性能的影响. 结果表明, CNTs/FeS类Fenton催化反应在H₂O₂浓度为20 mmol/L和CNTs/FeS催化剂的投加量为10 mg的条件下具有最优的降解效果, 其催化反应过程符合一级动力学方程, 且具有更加宽泛的pH适应范围(pH=3~8), 同时, CNTs/FeS类Fenton催化剂在使用寿命方面也具有一定的优势.     

高Co含量的Co-Mo系列催化剂甲烷裂解制备单壁纳米碳管

制备了高Co含量的Co-Mo／γ-A12O3系列催化剂，发现此类催化剂可以在温和的反应温度下制备高质量的单壁纳米碳管．讨论了Mo组分的作用．认为Mo分散、稳定金属颗粒，促进了SWNTs的生长．同时，Mo组分的升华决定了单壁纳米碳管的生长和管径分布．这为可控地制备单壁纳米碳管提供了依据．     

纳米碳管负载Co催化生长纳米碳管

In this paper, carbon nanotubes (CNTs) used as support and cobalt as catalyst to prepare new CNTs was studied. CNTs could grow well if the precursor CNTs were supported with Co on its surface. On the contrary, CNTs couldn’t grow at all if the precursor CNTs were not supported with Co. The TEM images showed that diameters of the obtained CNTs were different from those of the precursor CNTs. The pure CNTs could be prepared in this method without further purifying. The amount of Co on the precursor CNTs could affect the growth of CNTs greatly. When the content of metal on precursor CNTs was less than 16.2%, the amount of the obtained CNTs increased with the increasing amount of Co, and the maximum growth amount of 625% of CNTs could be obtained. But if the content of metal was more than 16.2%, the amount of Co had no influence on the growth of CNTs.     

碳纳米管负载Cu-Co复合氧化物的富氢气氛中CO催化消除

采用超声处理辅助浸渍法制备了多壁碳纳米管负载的Cu-Co复合氧化物催化剂. 利用XRD、TEM、H2-TPR、XPS和Raman光谱等表征了催化剂的结构性质. 在Cu和Co氧化物以及金属氧化物与碳纳米管载体间存在强相互作用. 催化剂在富氢气氛中CO催化消除反应中,与单一Cu或Co催化剂相比,Cu-Co复合氧化物催化剂表现出独特的反应特性,特别是在较高反应温度下可同时结合CO优先氧化和CO甲烷化的反应途径来实现高效CO消除. 当Cu/Co比为1/8时活性最优,可以实现在150-250℃和高反应空速 （120 L/（h·g））富氢气氛中CO的完全消除.     

Synthesis of Carbon Nanotubes by Catalytic Chemical Vapor Deposition Using Hydrogen Storage Alloy as A Catalyst

Carbon nanotubes, which was discovered by Iijima1 in 1991, is the most typical one-dimensional nano-material with the micrometers order in length and nanometers order in diameter. CNTs are composed of graphitic sheets rolled into closed concentric cylinders, and classed into single wall nanotubes and multi-wall nanotubes. CNTs can offer many significant advantages over most existing materials. Since its discovery, unprecedented interest has been stimulated because of its significance both in…     

氮掺杂竹节状碳纳米管的催化合成

以有机胺为碳和氮源, 用催化方法合成出了含氮大管径竹节状碳纳米管. Fe/SBA-15分子筛为催化剂, 有机胺经过973 K高温裂解得到氮掺杂竹节状碳纳米管材料(CN_X). 比较了铁含量、二乙胺和六次甲基四胺原料对合成氮掺杂碳纳米管形貌和氮掺杂量的影响; 合成出氮碳比(N/C原子比)为0.26的氮掺杂竹节状碳纳米管材料.     

含氮竹节状碳纳米管的催化合成

以二乙胺为原料，用催化方法合成出了含氮大管径竹节状碳纳米管，以含铁 SAPO-5分子筛为催化剂，二乙胺经过1073K高温裂解得到的碳纳米管材料，其内径 约60nm,壁厚为6nm，并且成竹节状。它有较高的表面和较高的氮碳比。     

Co-MCM-41催化剂上临CO2-乙烷脱氢反应的研究

合成了不同Co掺杂量的Co-MCM-41分子筛.用XRD,FTIR和TG-DTA等技术对所制样品进行表征.在常压连续流动固定床反应器上考察了它们对临CO₂-乙烷脱氢制乙烯反应的性能,结果表明,3%Co-MCM-41在973K可使乙烷的转化率达到39.54%,乙烯的选择性达到98.59%,收率达到38.98%.Co的掺杂量和反应温度等条件对该反应均有一定影响.Co-MCM-41对乙烷催化脱氢制乙烯同样也有很高的活性.引入CO₂可消除积炭对催化剂活性的影响,更有利于催化反应的进行.     

碳纳米管负载的铂催化剂对柠檬醛选择加氢及CO微分吸附热研究

碳纳米管(CNTs)是近年来发现的一种新型催化剂载体材料,将其作为α,β-不饱和醛的选择加氢的研究则报道较少．本文对柠檬醛[Citral,3,7-二甲基-2,6-辛二烯醛(3,7-Dimethyl-2,6-octadienal)]在Pt／CNTs和Pt／XC-72催化剂作用下的液相选择加氢进行了探索性研究．结果发现,碳纳米管(CNTs)负载的Pt催化剂具有生成不饱和醇的高选择性．