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水热法合成氧化镍-二氧化硅催化剂及其用于碳纳米管的制备 总被引:8,自引:0,他引:8
以硝酸镍和正硅酸乙酯为原料,制得Ni(OH)2/SiO2二元胶体,经水热晶化法和常压干燥法分别合成了纳米级氧化镍-二氧化硅复合粉体催化剂}用这两种催化剂在相同催化裂解条件下分别制得了多壁碳纳米管;采用XRD和TEM等测试手段对两种催化剂物相、形貌及由两种催化剂制得的碳纳米管形态、收率及纯度作了比较,结果表明:水热晶化法比常压干燥法合成的催化剂粉体颗粒粒径小(为10~20nm),分散性好,催化活性高,使得所制得的碳纳米管管径小(为10~16nm)、分布窄、纯度和收率都相对较高;同时对用不同水热反应温度合成的催化剂(物相不同)制备碳纳米管进行了研究。 相似文献
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以化学改性的膨润土为催化剂,利用化学气相沉积法催化裂解CH4,在高温条件下成功地制备了碳纳米管,并用透射电镜对其形貌与结构特征进行了表征。结果表明,所得产物形状弯曲,管径为15-20nm,长度达微米级的均匀碳纳米管;膨润土释放的金属铁起到了催化CH4的作用,在800℃条件下生长的碳纳米管质量最好、产率最高,若催化反应温度过高则会降低产品的质量,催化温度低于700℃时不能用来制备碳纳米管,与传统的过渡金属催化剂相比,这种矿物催化剂原料成本低廉,制备工艺简单,有利于碳纳米管的工业化生产。 相似文献
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Ho/Ni作为催化剂合成单壁碳纳米管 总被引:4,自引:4,他引:4
利用直流电弧等离子体方法,以Ho/Ni作为催化剂合成了单壁碳纳米管,借助扫描电子显微镜、拉曼光谱和热重分析方法对所合成的单壁碳纳米管的形貌、结构以及含量进行了表征。电镜观察以及热重分析表明,收集到的大量网状物中单壁碳纳米管含量较高;不同激发波长拉曼测量表明碳纳米管直径分布比较集中,在1.35nm~1.69nm范围,且直径为1.5nm的碳纳米管占多数;与Ce/Ni等作为催化剂合成的单壁碳纳米管的直径分布不同。研究结果表明,Ho/Ni对于合成单壁碳纳米管具有很好的催化效果且影响管径分布,元素Ho对单壁碳纳米管的形成起到了重要的作用。 相似文献
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碳源对碳纳米管形态的影响 总被引:7,自引:7,他引:0
以苯和甲苯为碳源,二茂铁为催化剂,含硫化合物为助催化剂,采用浮游催化裂解法制备了碳纳米管,并采用TEM对不同条件下所得碳纳米管进行了形态分析。结果发现,碳源中苯和甲苯的配比对碳纳米管的形态有着重要的影响。以纯苯为碳源时,产物主要为直线型碳纳米管,并存在极少量短的弯曲型碳纳米管。随着碳源中甲苯比例的增加,产物中折线型碳纳米管增加。以纯甲苯为碳源,产物中仍有少量直线型碳纳米管,而不完全是折线型碳纳米管;此外,产物中还发现了极少量分支型碳纳米管。根据所得结果讨论分析了甲苯的加入对碳纳米管形态的影响以及各种碳纳米管的形成机理,认为可能是由于甲苯在催化热解过程中产生的碳种不同于苯催化热解所产生的碳种,造成碳在催化剂颗粒各处浓度不同,从而在碳纳米管的不同部位引入五元环和七元环而形成各种形态的碳纳米管。 相似文献
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通过热引发方式使炸药-催化剂前驱体-碳氢化合物体系在密闭反应管中发生爆炸合成碳纳米管。采用TEM,HRTEM,XRD和TG等方法研究了以二茂铁、甲酸镍和乙酸钴作为催化剂前驱体对所合成碳纳米管产物的形貌、微观结构和纯度的影响。以乙酸钴为前驱体可以得到纯度较高(约80%~90%)、微观结构较好的管腔中空的碳纳米管。以二茂铁为前驱体,只有约10%~20%的碳管生成且多呈竹节状形貌。以甲酸镍为前驱体,得到的碳管纯度也不高(约10%~20%),碳管管壁富含结构缺陷,相当多的碳管端口膨胀成直径约为160nm的纳米泡。XRD分析表明这些催化剂前驱体在爆炸反应后均被分解、还原为金属单质。通过对生成的碳纳米管的质量和纯度进行比较,得出本方法中催化剂的催化活性依次为:钴>铁>镍,并对本方法中高碳源浓度环境下不同催化剂的活性差异作了简要分析。 相似文献
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Silver nanoparticles have been wrapped on multiwall carbon nanotubes though a green synthesis approach that has advantages over other conventional methods that involve chemical agents associated with environmental toxicity and damage of carbon nanotubes. Acacia was used as a green stabilizer for multiwall carbon nanotubes as well as a stabilizer and reducing agent for silver nanoparticles. Generation of silver-decorated multiwall carbon nanotubes was confirmed by UV-Vis spectrophotometry and X-ray diffraction. Generation of silver nanoparticles (5-10 nm) wrapped on MWCNTs was confirmed by field emission scanning electron microscopy and transmission electron microscopy. 相似文献
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Tarek Abdel-Fattah Emilie J. Siochi Roy E. Crooks 《Fullerenes, Nanotubes and Carbon Nanostructures》2006,14(4):585-594
Multi-wall carbon nanotubes were synthesized from sucrose by a pyrolytic technique using mesopourous MCM-41 silicate templates without transition metal catalysts. The nanotubes were examined in the carbon/silicate composite and after dissolution of the silicate. High-resolution transmission electron microscopy study of the multi-wall nanotubes showed them to be 15 nm in diameter, 200 nm in length and close-ended. There was variation in crystallinity with some nanotubes showing disordered wall structures. 相似文献
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根据绿色化学原理尝试探索一种合成多壁碳纳米管的天然可再生前驱体.应用化学气相沉积(CVD)法,采用一种天然可再生前躯体(椰仁油),通过系列步骤合成了MWCNTs.氮气既作为气化前驱体载气(气体流速:100mL/min)又维持合成在惰性氛围中进行.合成的MWCNTs使用SEM、EDX、TEM和Raman表征,最佳条件下得到的碳纳米管直径为80nm~90nm. 相似文献
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In this paper, Ag/C nanocables were synthesized via a one-step simple hydrothermal route by using glucose as reducing agent and carbon source, AgNO3 as silver source. The products are characterized in detail by multiform techniques: X-ray diffraction, energy-dispersive X-ray analysis, scanning electron microscopy, transmission electron microscopy. The results show that the obtained products are coaxial nanocables with lengths of several micrometers, about 200-500 nm in diameter, and a surrounding sheath about 80-100 nm in thickness. Different products including carbonaceous nanotubes and nanocables with fragmentary Ag core were obtained by adjusting time of chemical etching. 相似文献
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采用自制的实验装置, 通过阳极弧放电等离子体技术成功制备了Ni纳米颗粒填充的碳纳米管, 利用高分辨透射电子显微镜(HRTEM)、 XRD、 TEM、 X射线能量色散分析谱仪(XEDS)和振动样品磁强计(VSM)等测试手段对样品的化学成分、 形态、 微观结构和磁性能进行了表征。实验结果表明, 采用本文中实验方法能获得大量被纳米金属颗粒填充的碳纳米管, 其内部填充物为面心立方(FCC)结构的纳米Ni颗粒, 外围薄层为石墨碳层。碳纳米管的外径为30~40 nm, 壁厚5~8 nm, 内部填充的纳米颗粒呈球形和椭球形, 粒径均匀, 在管腔内不连续分布。产物具有顺磁特性, 矫顽力是78 Oe, 饱和磁化强度是33 enu/g。 相似文献
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镁钼氧化物催化剂制备多壁纳米碳管的初步研究 总被引:2,自引:0,他引:2
采用溶胶-凝胶法合成了可用来催化裂解甲烷大量制备高质量和较高纯度的多壁纳米碳管的镁钼氧化物催化剂. 实验表明该催化剂具有较高的活性和催化效率, 反应2h后, 制备的多壁纳米碳管的量接近原始催化剂量的30倍. 并用透射电镜、高分辨透射电镜、激光拉曼和热重分析对制得的粗产品进行了表征, 结果表明: 碳管的直径在10~22nm之间, 且随着反应时间的延长, 制备的纳米碳管石墨化程度增加, 反应1h后, 粗产品中碳管含量达95%, 同时, 对催化剂的特殊催化生长机理作了讨论, 生长过程中多层Mo颗粒析出在MgO载体表面是碳管成束的主要原因. 相似文献
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Y2O3:RE3+(RE=Eu, Tb, Dy) porous nanotubes were first synthesized using carbon nanotubes as template. The morphology of the coated precursors and porous Y2O3:Eu3+ nanotubes was determined by scanning electron Microscopy (SEM) and transmission electron microscopy (TEM). It was found that the coating of precursors on carbon nanotubes (CNTs) is continuous and the thickness is about 15 nm, after calcinated, the Y2O3:Eu3+ nanotubes are porous with the diameter size in the range of 50-80 nm and the length in micrometer scale. X-ray diffraction (XRD) patterns confirmed that the samples are cubic phase Y2O3 and the photoluminescence studies showed that the porous rare earth ions doped nanotubes possess characteristic emission of Eu3+, Tb3+, and Dy3+. This method may also provide a novel approach to produce other inorganic porous nanotubes used in catalyst and sensors. 相似文献
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Polyphosphazene nanotubes with about 20 nm in inner diameter and 100-200 nm in outer diameter were fabricated easily and then carbonized at 800 °C in a nitrogen atmosphere. Scanning electron microscopy and transmission electron microscope results showed that the bulk morphology of polyphosphazene nanotubes was retained after carbonization. The carbon content of the carbonized samples reached 93.28%. X-ray diffraction and Raman spectrum showed that the carbonized samples had low graphitization state. The present method can be used for a mass production of carbon nanotubes. 相似文献