乙醇催化裂解法制备高储氢量碳纳米管

采用乙醇催化裂解法制备碳纳米管,有效解决了以烃为碳源制备的碳纳米管的团聚、长度不可控、分离纯化复杂、得率低的难题。透射电镜和Raman光谱分析表明,使用乙醇催化裂解法可以直接制备纯度高、管长适中的离散碳纳米管。这种碳纳米管在600℃以下时不分解,吸附性能优异,在298℃、15MPa时最大吸氢量为6.90%,远高于以苯为碳源制备的碳纳米管的最大吸氢量(1.65%),已达到美国能源车用储氢系统的标准。     

乙醇裂解协同制备氢气和碳纳米管

以乙醇为碳源,采用浸渍法制备的担载量为Fe(5%)/C催化剂,利用化学气相沉积法协同制备碳纳米管和氢气,分析了裂解温度(500⁸00℃)对于产生氢气产率和碳纳米管品质的影响。对于Fe(5%)/C催化裂解乙醇,最佳的反应温度为600℃,碳管的品质较好,氢气的产率最高为75%,生成的碳管为多壁碳纳米管。     

以无毒液体石蜡为碳源制备多壁碳纳米管

以无毒的液体石蜡为碳源、二茂铁为催化剂前驱体、含硫化合物二甲基亚砜为生长促进剂,采用浮动催化热分解法制备多壁碳纳米管,通过TEM、SEM、XRD、Ram an、TG等对产物形貌和结构进行了表征。结果表明,在1 100~1 280℃条件下,能够制备出晶化程度较高的多壁碳纳米管,并且随着温度的升高,多壁碳纳米管由弯曲型向直形转变。     

乙醇裂解制备碳纳米管及其生长机理研究

以乙醇作为碳源,Mo-Co/C和Mo-Fe/C作为催化剂,采用化学气相沉积法,高温裂解乙醇制备碳纳米管.利用SEM和TEM对碳纳米管形貌和结构进行表征.结果表明:乙醇在催化剂Mo-Co/C和Mo-Fe/C裂解产生的碳纳米管遵循顶部生长机理.并建立了乙醇制备碳纳米管的生长模型.     

化学气相沉积法低温制备氢气和多壁碳纳米管

采用低温化学气相沉积法裂解乙醇协同制备氢气和多璧碳纳米管,乙醇作为碳源,Ni/C用作催化剂。考察反应温度和Ni/C比例对氢气的产率和碳纳米管品质的影响。多壁碳纳米管结构与组成通过扫描电镜、投射电镜和X射线粉末衍射进行表征。结果表明:Ni/C催化剂最佳Ni担载量为8%,最佳的反应温度为500℃,最佳条件下氢气的产率为79%,碳纳米管的品质最佳。     

碳纳米管填充PDMS膜的渗透汽化性能

将碳纳米管（CNTs）填充到PDMS中制备出CNTs/PDMS杂化膜,并将其用于乙醇/水体系的分离,发现由多壁碳纳米管制备的膜分离性能优于单壁碳纳米管填充膜,在40℃下,进料乙醇浓度为5%（质量分数）时,膜的分离因子可由8.3提高到10.0,渗透通量为206.2 g·（m²·h）^-1;采用十二烷基三氯硅烷对多壁碳纳米管进行修饰,并对修饰前后碳纳米管的性能进行表征,研究表明修饰后碳纳米管表面形成疏水层,碳纳米管的疏水性增强;将修饰后的碳纳米管填充到PDMS中,可进一步提高杂化膜对乙醇的选择性,膜的分离因子可提高到11.3,渗透通量为130.9 g·（m²·h）^-1。     

聚苯胺接枝多壁碳纳米管的制备及热电性能

通过原位聚合,将聚苯胺接枝到多壁碳纳米管的表面,制备了聚苯胺/碳纳米管纳米纤维。聚苯胺均匀地包覆在碳纳米管表面,当苯胺与碳纳米管投料比为1∶1时,包覆层厚度约为15 nm。聚苯胺/多壁碳纳米管的电导率和塞贝克系数随温度升高而增大,且增大碳纳米管含量同时提高了复合材料的电导率和塞贝克系数,改善了功率因子。     

薄壁开口定向氮掺杂碳纳米管的制备及其优异的场发射性能

以乙腈为碳源，二茂铁为催化剂，用化学气相沉积（CVD）法，制备了薄壁开口定向氮掺杂的多壁碳纳米管。在780℃～860℃的生长温度范围内，随着温度的升高，碳纳米管的场发射效应增强。当生长温度为860℃时，制备碳纳米管的开启电场为0．27V／μm，阀值电场为0．49V／μm，增强因子为1．09×10^5。与其他材料相比，这种碳纳米管体现了非常优越的场发射性能。     

碳纳米管/聚苯胺复合材料的原位合成及其形成机理

用竖式炉流动法,以二茂铁为催化剂,硫为助催化剂,苯为碳源通过催化裂解反应在1100～1200℃制备了直线形多壁碳纳米管,碳纳米管外径为20～50nm,内径10～30nm,长度50～1000μm。在碳纳米管表面原位合成了聚苯胺,制备出碳纳米管/聚苯胺一维纳米复合材料,复合材料的直径为50～60nm。X射线衍射及热重分析表明,原位合成的聚苯胺的结晶程度和热稳定性较高,聚苯胺在碳纳米管表面以枝晶状生长,探讨了聚苯胺在碳纳米管表面的形成机理。     

以太西无烟煤为碳源制备单壁碳纳米管

以太西无烟煤为碳源,研究了用直流电弧放电法大批量制备单壁碳纳米管的工艺条件,考察了放电气氛及压力、催化剂种类及其用量和煤基炭棒的炭化终温对单壁碳纳米管产率的影响,采用发射光谱技术对电弧等离子体进行了实时监测,用透射电子显微镜、拉曼光谱技术、热重技术和物理吸附技术等对单壁碳纳米管产品进行了分析表征。研究表明,以稀土氧化物Y2O3和过渡金属Ni为催化剂、煤基炭棒为阳极,在0.05MPa氦气下电弧放电,可实现单壁碳纳米管的批量制备,单壁碳纳米管的产量随着煤基炭棒炭化终温的升高而增大。电弧放电得到的煤基单壁纳米碳管以管束形式存在;单壁碳纳米管粗产品中金属催化剂含量低于40%(质量);所得到的煤基单壁碳纳米管的直径在1.5～2.4nm之间,比表面积为199m2.g-1,孔容为0.388cm3.g-1,其中中孔占60%。光谱分析表明,电弧等离子体中存在大量的C和一定的CN活性物种。     

Preparation of Isolated Single-walled Carbon Nanotubes with High Hydrogen Storage Capacity

Isolated single-walled carbon nanotubes with high proportion of opening tips were synthesized by using alcohol as carbon source. The mechanism of cutting action of oxygen was proposed to explain its growth. Compared with carbon nanotubes synthesized with benzene as carbon source, their specific surface area was heightened by approximately 2.2 times (from 200.5 to 648 m2/g) and the hydrogen storage capacity was increased by approximately 6.5 times (from 0.95 to 7.17%, w) which had exceeded DOE energy standard of vehicular hydrogen storage.     

Synthesis of carbon nanocapsules and carbon nanotubes by an acetylene flame method

The fabrication of carbon nanocapsules and carbon nanotubes (CNTs) using an acetylene flame method was investigated. Carbon nanocapsules, a graphitic structure of nanoparticles with a hollow core, were synthesized using catalyst-free acetylene flames while CNTs were formed with the presence of cobalt-based catalysts in addition to acetylene flames. When the synthesis of these materials was carried out, the results showed that a massive amount of high-purity carbon nanocapsules with a particle size in the range of 15-30 nm can be produced with the acetylene flame method. The CNTs produced were multi-walled carbon nanotubes measuring a few micrometers in length and 20-30 nm in diameter. The acetylene flame method holds great potential for the cost-effective production of CNTs as well as carbon nanocapsules.     

New continuous gas-phase synthesis of high purity carbon nanotubes by a thermal plasma jet

We have developed a new gas-phase synthesis technique to produce carbon nanotubes (CNTs) with a continuous process and at high temperature, by using a thermal plasma jet. A thermal plasma jet was generated by applying a direct current of 100-300 A, using Ar as the plasma gas with a flow rate of ∼6 ksccm. The temperature of the thermal plasma jet was very high (∼10⁴ K) and the velocity was very fast (∼100 m/s). Fe(CO)₅ and CO were used as a catalyst precursor and carbon source, respectively. The yield of CNTs was dramatically increased by attaching a helical extension reactor at the end of the plasma nozzle. High purity (∼80%) CNTs were produced with a continuous process by using a thermal plasma jet with helical extension reactor equipment. The number of CNT walls produced was critically affected by the hydrogen gas injected as an auxiliary plasma gas. Without hydrogen gas, single-walled carbon nanotubes whose diameter was about 1 nm were mostly produced while with hydrogen gas double-walled carbon nanotubes (about 4 nm in diameter) were predominantly produced, with small amount of 3- and 4-walled carbon nanotubes.     

多壁碳纳米管分散性研究

通过对多壁碳纳米管的改性研究,寻找提高碳纳米管分散性的途径。采用NaOH对碳纳米管进行预处理,通过SEM、DSC分析表明,该处理过程对去除多壁碳纳米管中杂质和提高其分散性有积极效果。通过H2SO4和HNO3的混酸处理法与HNO3处理法的对比,知前者对碳纳米管的损失要大于后者,且通过对FTIR的对比分析,后者对碳纳米管的改性效果好于前者。TG、TEM分析表明,聚乙烯醇均匀包覆在碳纳米管表面,碳纳米管分散性较酸处理的有所改进。     

Catalytic synthesis of SiC nanowires in an open system

SiC nanowires (NWs) are usually synthesized in a closed vacuum reaction system which limits the yield of SiC NWs. In this work, SiC NWs and carbon nanotubes were synthesized in an open tube furnace at 1550°C with Si powder as silicon sources, ethanol as carbon sources and ferrocene as catalyst. The as-synthesized products were ultralong β-SiC NWs with the diameter about 80-100 nm and the length up to several tens micrometers. The diameter of the carbon nanotubes was about 20-30 nm. The carbon nanotube yarns about 20 cm in length were obtained at the end of the tube furnace. The growth mechanism of SiC NWs and carbon nanotubes were proposed. Compared with the traditional synthetic techniques in the high vacuum closed system, the novel synthesis method in the open system provided a new approach to the synthesis of SiC NWs.     

化学气相沉积工艺制备绳状纳米碳管的研究

用硝酸铁作催化剂,乙炔作碳源气体,高纯氮气作稀释气体,在750℃下化学气相沉积生长了绳状纳米碳管,用高分辨扫描电镜观察了所得绳状纳米碳管的形貌.纳米碳管的直径为100～200nm,长度为10～20 μm.文中还提出了绳状纳米碳管的生长机理.     

Single-source precursor route to carbon nanotubes at mild temperature

Carbon nanotubes were synthesized via a single-source precursor route at 500 °C, using iron carbonyl both as carbon source and catalyst. The X-ray power diffraction pattern indicates that the products are hexagonal graphite. Transmission electron microscope (TEM) images of the sample reveal carbon nanotubes with an average inner (outer) diameter of 30 nm (60 nm). High-resolution TEM indicates that fabrication of the carbon nanotube walls was composed of ca. 40 graphene layers. The Raman spectrum shows two strong peaks at 1587 and 1346 cm⁻¹, corresponding to the typical Raman peaks of graphitized carbon nanotubes. This method avoids the separation of raw material from solvent and simplifies the operation process. At the same time, the research provides a new route to large-scale synthesis of carbon nanotubes.     

邻苯二甲酸单醇酯钠盐的合成及性能研究

分别用十二醇、十四醇、十六醇和十八醇与邻苯二甲酸酐反应合成邻苯二甲酸单醇酯,再用氢氧化钠中和得钠盐。研究了催化剂、醇、原料配比、酯化温度及溶剂等对单酯酯化率的影响,用红外光谱和核磁共振波谱对产物结构进行了表征,测定其泡沫性能和界面性能。确定了最佳酯化条件为:以自制催化剂BN-1作催化剂,二甲苯为溶剂,n(醇)∶n(酸酐)=1∶1.6,酯化温度100℃,酯化时间5 h。随着醇碳链增加,邻苯二甲酸单醇酯钠盐泡沫能力降低,但界面活性增强。     

碳包铁颗粒和放射状碳纳米管微观结构的研究

以苯和甲苯为碳源，二茂铁为催化剂前驱体，含硫化合物为助催化剂，采用竖式炉流动催化法，通过减小载人的氢气量以改变催化剂颗粒的状态及反应条件，获得了碳包铁颗粒以及放射状碳纳米管，运用TEM和HRTEM对其形貌和结构进行了分析，并初步探讨了其生长机理。结果表明，在碳源、催化剂和炉温分布相同的条件下，氢气量为5400mL／min时形成直线型和弯曲型两种不同形态的碳纳米管，后者管径大于前者。氢气量为2000mL／min时，产物90％以上为碳包铁颗粒，其平均直径约为530nm，其中还有少量放射状碳纳米管，其外径为45—50nm，内径为3—5nm，管径较为均匀。     

Synthesis and characterization of double-walled carbon nanotubes from multi-walled carbon nanotubes by hydrogen-arc discharge

Double-walled carbon nanotubes (DWNTs) were synthesized in a large scale by a hydrogen arc discharge method using graphite powders or multi-walled carbon nanotubes/carbon nanofibers (MWNTs/CNFs) as carbon feedstock. The yield of DWNTs reached about 4 g/h. We found that the DWNT product synthesized from MWNTs/CNFs has higher purity than that from graphite powders. The results from high-resolution transmission electron microscopy observations revealed that more than 80% of the carbon nanotubes were DWNTs and the rest were single-walled carbon nanotubes (SWNTs), and their outer and inner diameters ranged from 1.75 to 4.87 nm and 1.06 to 3.93 nm, respectively. It was observed that the ends of the isolated DWNTs were uncapped and it was also found that cobalt as the dominant composition of the catalyst played a vital role in the growth of DWNTs by this method. In addition, the pore structures of the DWNTs obtained were investigated by cryogenic nitrogen adsorption measurements.