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Purified oxygenand nitrogen-modified multi-walled carbon nanotubes as metal-free catalysts for selective olefin hydrogenation 被引量:2
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作者 Peirong Chen Ly May Chew +3 位作者 Aleksander Kostka Kunpeng Xie Martin Muhler Wei Xia 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2013年第2期312-320,共9页
Oxygen and nitrogen-functionalized carbon nanotubes (OCNTs and NCNTs) were applied as metal-free catalysts in selective olefin hydro- genation. A series of NCNTs was synthesized by NH3 post-treatment of OCNTs. Tempe... Oxygen and nitrogen-functionalized carbon nanotubes (OCNTs and NCNTs) were applied as metal-free catalysts in selective olefin hydro- genation. A series of NCNTs was synthesized by NH3 post-treatment of OCNTs. Temperature-programmed desorption, N2 physisorption, Raman spectroscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were employed to characterize the surface properties of OCNTs and NCNTs, aiming at a detailed analysis of the type and amount of oxygen- and nitrogen-containing groups as well as surface defects. The gas-phase treatments applied for oxygen and nitrogen functionalization at elevated temperatures up to 600 ℃ led to the increase of surface defects, but did not cause structural damages in the bulk. NCNTs showed a clearly higher activity than the pristine CNTs and OCNTs in the hydrogenation of 1,5-cyclooctadiene, and also the selectivity to cyclooctene was higher. The favorable catalytic properties are ascribed to the nitrogen-containing surface functional groups as well as surface defects related to nitrogen species. In contrast, oxygen-containing surface groups and the surface defects caused by oxygen species did not show clear contribution to the hydrogenation catalysis. 展开更多
关键词 multi-walled carbon nanotubes nitrogen-containing functional groups oxygen-containing functional groups metal-free catalyst selectiveolefin hydrogenation
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Multi-walled carbon nanotubes as novel promoter of catalysts for certain hydrogenation and dehydrogenation reactions 被引量:2
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作者 Guodong Lin Xuelian Liang +3 位作者 Zhiming Liu Jianrong Xie Binghui Chen Hongbin Zhang 《Science China Chemistry》 SCIE EI CAS CSCD 2015年第1期47-59,共13页
From the chemical catalysis viewpoint,the excellent performance of CNTs in adsorption-activation of H2 and in promoting spillover of adsorbed H-species is very attractive,in addition to their nanosize channels,sp2-C c... From the chemical catalysis viewpoint,the excellent performance of CNTs in adsorption-activation of H2 and in promoting spillover of adsorbed H-species is very attractive,in addition to their nanosize channels,sp2-C constructed surfaces,and high thermal/electrical conductivity.This review examines some recent progresses of CNTs as a novel support or promoter of catalysts for certain hydrogenation or dehydrogenation reactions,e.g.,hydrogenation-conversion of syngas to yield alcohols and decomposition or steam-reforming of methanol to generate H2,mainly based on recent work carried out in our laboratory. 展开更多
关键词 multi-walled carbon nanotubes catalysts supported or promoted by CNTs hydrogenation-conversion of syngas toalcohols decomposition or steam-reforming of methanol to yield H2
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Multi-walled Carbon Nanotubes as a Ligand in Nickel ?-Diimine Based Ethylene Polymerization 被引量:1
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作者 Sasan Talebnezhad Saeed Pourmahdian 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2015年第10期1389-1403,共15页
Two novel heterogeneous nickel a-diimine based polymerization catalysts, containing MWCNT as the main ligand, were synthesized by novel in situ catalyst preparation technique. The in situ synthesis was performed by co... Two novel heterogeneous nickel a-diimine based polymerization catalysts, containing MWCNT as the main ligand, were synthesized by novel in situ catalyst preparation technique. The in situ synthesis was performed by covalent attachment of the acenaphthenic ligand core to amine functionalized MWCNT ligand arms through diimine bonding and further nickel dibromide chelation. The prepared catalysts were fully characterized and their structures and supporting efficiencies were determined. Single or double introduction of the MWCNTs through their ends or sidewall(s) in the catalytic system, as a ligand, influenced the catalytic performance, microstructure and morphology of obtained polyethylenes. MWCNT sidewall bonding to para-aryl position of the tetramethylphenyl moiety performed as more electron-donating ligand than MWCNT ends linked to the imine bond and protected the catalytic system to retain its activity. This character resulted in the maintenance of the resulting polymer topology at elevated temperatures so that the catalytic activity and the obtained polymer melting points remained around 110 g PE·mmol^-1 Ni·h^-1 and 123 ℃ in all polymerization temperatures respectively. In polymerization trials, molecular weight fall against temperature was not as sharp as what had been observed in sequentially prepared catalysts insofar as the molecular weight of resultant polymer at 60 ℃ reached to 310000 g·mol^-1 which was close to the highest value had been reported at 30 ℃ for sequentially prepared catalysts. TEM observations showed the presence of the stopped-growth polymer chains due to geometrical constrains or ligand debonding for both catalytic systems. 展开更多
关键词 a-Diiminonickel catalyst LIGAND multi-walled carbon nanotubes Ethylene polymerization In situ catalyst preparation.
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Photocatalytic Degradation of Phenol over MWCNTs-TiO2 Composite Catalysts with Different Diameters
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作者 李晨 汪文栋 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2009年第4期423-428,448,共7页
Titania-based composite catalysts were prepared through a sol-gel route employing multi-walled carbon nanotubes with different diameters. The materials were characterized using thermogravimetric analysis, nitrogen ads... Titania-based composite catalysts were prepared through a sol-gel route employing multi-walled carbon nanotubes with different diameters. The materials were characterized using thermogravimetric analysis, nitrogen adsorption-desorption isotherm, powder X-ray diffraction, scanning electron microscopy, and diffuse reflectance UV-Vis absorption spectra. The application of the catalysts to photocatalytic degradation of phenol was tested under UV-Vis irradiation. A synergetic effect on phenol removal was observed in case of composite catalysts, which was evaluated in terms of apparent rate constant, total organic carbon removal and photonic efficiency. 展开更多
关键词 Photocatalytic degradation PHENOL Titanium dioxide multi-walled carbon nanotube Composite catalyst
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Novel MWCNT-Support for Co-Mo Sulfide Catalyst in HDS of Thiophene and HDN of Pyrrole 被引量:6
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作者 Kunming Dong Xiaoming Ma Hongbin Zhang Guodong Lin 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2006年第1期28-37,共10页
With home-made multi-walled carbon nanotubes (MWCNTs, simplified as CNTs in later text) as support, CNT-supported Co-Mo-S catalysts, denoted as x%(mass percentage)MoiCoj/CNTs, were prepared. Their catalytic perfor... With home-made multi-walled carbon nanotubes (MWCNTs, simplified as CNTs in later text) as support, CNT-supported Co-Mo-S catalysts, denoted as x%(mass percentage)MoiCoj/CNTs, were prepared. Their catalytic performance for thiophene hydrodesulfurization (HDS) and pyrrole hydrodenitrification (HDN) reactions was studied, and compared with the reference system sup- ported by AC. Over the 7.24%Mo3Co1/CNTs catalyst at reaction condition of 1.5 MPa, 613 K, C4H4S/H2=3.7/96.3(molar ratio) and GHSV≈8000 mlswP/(g-cat.h), the specific HDS activity of thiophene reached 3.29 mmolc4H4S/(s.molMo), which was 1.32 times as high as that (2.49 mmolc4H4S/(s.molMo)) of the AC-based counterpart, and was 2.47 times as high as that (1.33 mmolc4H4S/(s-molMo)) of the catalysts supported by AC with the respective optimal MoaCol-loading amount, 16.90%Mo3Co1/AC. Analogous reaction-chemical behaviours were also observed in the case of pyrrole HDN. It was experimentally found that using the CNTs in place of AC as support of the catalyst caused little change in the apparent activation energy for the thiophene HDS or pyrrole HDN reaction, but led to a significant increase in the concentration of catalytically active Mo-species (Mo^4+) at the surface of the functioning catalyst. On the other hand, H2-TPD measurements revealed that the CNT-supported catalyst could reversibly adsorb a greater amount of hydrogen under atmospheric pressure at temperatures ranging from room temperature to about 673 K. This unique feature would help to generate microenvironments with higher stationarystate concentration of active hydrogen-adspecies at the surface of the functioning catalyst. Both factors mentioned above were favorable to increasing the rate of thiophene HDS and pyrrole HDN reactions. 展开更多
关键词 multi-walled carbon nanotube Mo-Co-S/CNTs catalyst thiophene hydrodesulphurization pyrrole hydrodenitrification
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Co-Mo/MgO催化剂上甲烷化学气相沉积制备高纯度多壁碳纳米管(英文) 被引量:2
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作者 Wei-Ming Yeoh Kim-Yang Lee +2 位作者 Siang-Piao Chai Keat-Teong Lee Abdul Rahman Mohamed 《新型炭材料》 SCIE EI CAS CSCD 北大核心 2009年第2期119-123,共5页
以甲烷为碳源,Co-Mo/MgO为催化剂,通过气相化学沉积制备了直径均匀的多壁碳纳米管(MWC-NTs)。采用溶胶-凝胶法所制双金属催化剂的组成为Co∶Mo∶MgO=5∶20∶75(质量比)。热重分析表明多壁碳纳米管产率高达313.67%。催化剂对于多壁碳纳... 以甲烷为碳源,Co-Mo/MgO为催化剂,通过气相化学沉积制备了直径均匀的多壁碳纳米管(MWC-NTs)。采用溶胶-凝胶法所制双金属催化剂的组成为Co∶Mo∶MgO=5∶20∶75(质量比)。热重分析表明多壁碳纳米管产率高达313.67%。催化剂对于多壁碳纳米管生长的选择性是91.17%(其余为无定形碳)。透射电子显微镜分析显示:催化剂上生长的MWCNTs平均直径为6.2±0.5nm(平均±标准偏差)。通过稀酸的简单纯化处理,纯化样品的催化剂残存率降至0.72%。 展开更多
关键词 催化 多壁碳纳米管 易脱除的催化剂 催化化学气相沉积
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