共查询到17条相似文献,搜索用时 62 毫秒
1.
2.
Cuong Duong-Viet Housseinou Ba Yuefeng Liu Lai Truong-Phuoc Jean-Mario Nhut Cuong Pham-Huu 《催化学报》2014,35(6):906-913
A hierarchical metal-free catalyst consisting of nitrogen-doped carbon nanotubes decorated onto a silicon carbide (N-CNTs/SiC) macroscopic host structure was prepared. The influence of N-CNTs incorporation on the physical properties of the support was evaluated using different characterization techniques. The catalyst was tested as a metal-free catalyst in the selective oxidation of H2S and steam-free dehydrogenation of ethylbenzene. The N-CNTs/SiC catalyst exhibited extremely good desulfurization performance compared to a Fe2O3/SiC catalyst under less conducive reaction conditions such as low temperature, high space velocity, and a low O2-to-H2S molar ratio. For the dehy-drogenation of ethylbenzene, a higher dehydrogenation activity was obtained with the N-CNTs/SiC catalyst compared to a commercial K-Fe/Al2O3 catalyst. The N-CNTs/SiC catalyst also displayed good stability as a function of time on stream for both reactions, which was attributed to the strong anchoring of the nitrogen dopant in the carbon matrix. The extrudate shape of the SiC support allowed the direct macroscopic shaping of the catalyst for use in a conventional fixed-bed reactor without the problems of catalyst handling, transportation, and pressure drop across the catalyst bed that are encountered with nanoscopic carbon-based catalysts. 相似文献
3.
4.
Olga Yu. Podyacheva Andrei I. Stadnichenko Svetlana A. Yashnik Olga A. Stonkus Elena M. Slavinskaya Andrei I. Boronin Andrei V. Puzynin Zinfer R. Ismagilov 《催化学报》2014,35(6):960-969
The nanocomposites based on cobalt oxide and nitrogen-doped carbon nanofibers (N-CNFs) with cobalt oxide contents of 10–90 wt% were examined as catalysts in the CO oxidation and supercapacity electrodes. Depending on Со3О4 content, such nanocomposites have different morphologies of cobalt oxide nanoparticles, distributions over the bulk, and ratios of Со3+/Co2+ cations. The 90%Со3О4-N-CNFs nanocomposite showed the best activity because of the increased concentration of defects in N-CNFs. The capacitance of electrodes containing 10%Со3О4-N-CNFs was 95 F/g, which is 1.7 times higher than electrodes made from N-CNFs. 相似文献
5.
在铁基催化剂(Fe-N-C)中引入金属铈,采用高温热解法合成了氮掺杂碳纳米管(NCNTs)高负载金属催化剂(Fe/Ce-NCNTs)。金属铈的引入能更好地促进碳纳米管(CNTs)的生长,锚定更多的铁原子,增加Fe—NX活性位点的数量。Fe/CeNCNTs催化剂在碱性介质中表现出良好的催化活性和稳定性,半波电位为0.86 V(vs RHE)。将Fe/Ce-NCNTs催化剂应用于铝空气电池(AABs),其峰值功率密度可达142 mW·cm-2,在50 mA·cm-2电流密度下放电比容量达到865 mAh·g-1,在高电流密度负载下具有较高的电压。 相似文献
6.
在铁基催化剂(Fe-N-C)中引入金属铈,采用高温热解法合成了氮掺杂碳纳米管(NCNTs)高负载金属催化剂(Fe/Ce-NCNTs)。金属铈的引入能更好地促进碳纳米管(CNTs)的生长,锚定更多的铁原子,增加 Fe—NX活性位点的数量。Fe/Ce-NCNTs催化剂在碱性介质中表现出良好的催化活性和稳定性,半波电位为 0.86 V(vs RHE)。将 Fe/Ce-NCNTs催化剂应用于铝空气电池(AABs),其峰值功率密度可达142 mW·cm-2,在50 mA·cm-2电流密度下放电比容量达到865 mAh·g-1,在高电流密度负载下具有较高的电压。 相似文献
7.
8.
碳纳米管负载铑催化剂上丙烯氢甲酰化 总被引:21,自引:0,他引:21
Effect of carbon nanotubes, as a novel support material, on the performance of Rh-catalyst supported by them was studied. Catalysts based on carbon nanotubes, SiO2, carbon molecular sieves, active carbon, and GDX-l02(a copolymer of styrene with divinylbenzene),were prepared, and their catalytic behaviors for propene hydroformylation were investigated and compared. The results showed that, over the carbon nanotubes-supported Rh-catalyst, C3H6 conversion and regioselectivity of butyric aldehyde (represented by n/i, a ratio of n-butyric aldehyde to its isomer, i-butyric aldehyde, in the products) were pronouncedly improved: the average turnover frequency(TOF) for the catalytic hydroformylation of propene was 0.079 s-1 at 393K, which was 2.1 times faster than that over the Rh catalyst based on SiO2, and the n/i ratio of the aldehyde products reached to 11.6, which was 1.9 times higher than that over the catalyst based on SiO2. The roles of six-membered C-ring at the surface of the carbon-nanotubes on the stability of the catalytically active Rh-complexes and of the tubular nano-channel on the spatiospecific seletivity of reaction intermediate state and butyric aldehyde produced were discussed. 相似文献
9.
近年来, 过渡金属催化剂对CO的化学吸附已有较多的理论研究报道[1~3]. 但由于涉及到含d电子较多的过渡金属, 大多数的计算仍采用半经验方法, 即使有些计算采用了非经验方法, 但所用基组小[4,5], 考虑电子的相关作用较少. 由于对过渡金属体系用包括电子相关作用的计算方法是必要的[6], 故本文采用DFT计算方法[7]和LANL1DZ基组[8,9]进行了计算, 并在前文[10]基础上, 集中讨论SiO2的担体作用. 担体在催化剂中占有很重要的地位, 但其发挥什么作用, 一直是被探讨的重要理论课题. 本文选择以SiO2为担体研究对象, 仍以Ru, Rh, Pd为金属催化剂活性组分, 对担体如何影响CO的化学吸附和金属的催化选择性进行理论探讨, 并进一步推测最终对CO氢化反应产物的影响. 相似文献
10.
The hydrodenitrogenation(HDN) of porphyrins was carried out over a series of phosphorus containing NiMo/Al 2 O 3 catalysts using a fixed‐bed flow reaction system.A method of quantitative analysis of the porphyrin and its derivatives produced by HDN was established.In HDN of porphyrin,four types of hydrocarbons:C8 alkanes,C 8 alkenes,C9 alkanes,and C10 alkanes,and two groups of nitrogen‐containing compounds:alkyl substituted bipyrrolidines(alkylbipyrrolidines) and alkyl substituted tripyrrolidines(alkyltripyrrolidines) were identified.The hydrogenolysis of porphyrins occurred rapidly at lower temperature but higher temperatures were required for the HDN of porphyrins.The NiMoP3 catalyst showed the highest catalytic activity for the HDN of porphyrins.Based on the characterization of the supports and catalysts,it is suggested that the dispersion of Mo is improved and the number of weak acidic sites on the NiMoP catalysts increases with the addition of phosphorus. 相似文献
11.
《印度化学会志》2021,98(3):100035
Acetone is a product which is obtained via several processes. It is produced mainly by cumene hydroperoxide process. As an alternative process, acetone is obtained by isopropyl alcohol (IPA) dehydrogenation. The conversion of IPA to acetone is an endothermic gas-phase reaction which produces hydrogen as a byproduct. The process consists of an equilibrium reactor or kinetic reactor (EREA), a distillation column (SCDS), and a flash tank. As the fresh feed, liquid-phase IPA, combined with a recycle stream which contains slight amount of unseparated acetone, is vaporized and given into the equilibrium reactor. Reactor effluent is then cooled by two heat exchangers and pressurized by a compressor until unreacted IPA and formed acetone are liquidised. This stream is fed to a flash tank in order to separate the gas-phase hydrogen, which contains slight amount of acetone. The distillation column distinguishes the acetone from unreacted IPA. The distillate stream has an acetone purity over 99%. The bottoms stream, which consists of residual IPA and slight amount of acetone, is recycled back into the mixer. The purpose of this study is to improve the simulation of isopropyl alcohol (IPA) dehydrogenation process by using the ChemCad program in terms of industrial applications. 相似文献
12.
Zhao Chu Hu Shan Gao Sheng Hong Hu Yong Sheng Liu Hai Hong Chen 《中国化学快报》2007,18(10):1297-1300
Isopropyl alcohol matrix effect was found to be element specific by using the defined matrix effect factor in ICP-MS,which could not be corrected by using the conventional internal reference method.Unlike the conventional internal reference method,the presented method allows for the analyte to behave differently from the internal reference under the influence of the matrix. 相似文献
13.
Avelino Corma Hermenegildo Garcia Antonio Leyva 《Journal of molecular catalysis. A, Chemical》2005,230(1-2):97-105
Nanoparticles (2–10 nm) of palladium have been deposited on single wall carbon nanotubes (SWNT) by spontaneous reduction from Pd(OAc)2 or from oxime carbapalladacycle. These catalysts exhibit higher catalytic activity than palladium over activated carbon (Pd/C) for the Heck reaction of styrene and iodobenzene and for the Suzuki coupling of phenylboronic and iodobenzene. This fact has been attributed as reflecting the dramatic influence of the size particle on the activity of the palladium catalyst for CC bond forming reactions as compared to other reaction types less demanding from the point of view of the particle size. Thus, in contrast to the Heck and Suzuki reactions, Pd/C is more active than palladium nanoparticles deposited on SWNT for the catalytic oxidation by molecular oxygen of cinnamyl alcohol to cinnamaldehyde and for the hydrogenation of cinnamaldehyde to 3-phenylpropionaldehyde. 相似文献
14.
A nitrogen-doped graphene/carbon nanotubes (NGR–NCNTs) nanocomposite was employed into the study of the electrochemical sensor via electrodeposition for the first time. The morphology and structure of NGR–NCNTs nanocomposite were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. Meanwhile, the electrochemical performance of the glassy carbon electrode (GCE) modified with electrodeposited NGR–NCNTs (ENGR–NCNTs/GCE) towards caffeine (CAF) and vanillin (VAN) determination was demonstrated by cyclic voltammetry (CV) and square wave voltammetry (SWV). Under optimal condition, ENGR–NCNTs/GCE exhibited a wide linearity of 0.06–50 μM for CAF and 0.01–10 μM for VAN with detection limits of 0.02 μM and 3.3 × 10−3 μM, respectively. Furthermore, the application of the proposed sensor in food products was proven to be practical and reliable. The desirable results show that the ENGR–NCNTs nanocomposite has promising potential in electrocatalytic biosensor application. 相似文献
15.
The influence of asymmetric catalytic particles prepared by various methods was investigated on the growth of spiral carbon
nanotubes using the CVD method. Asymmetric particles were prepared by either milling or crystallization from oversaturated
solution onto the surface of catalyst support or catalyst impregnation at pH 8–9. As-prepared catalysts were tested in the
decomposition of acetylene. Carbon deposit, thus carbon nanotubes and spirals were observed by transmission electron microscopy
the activity was characterized by carbon yield. 相似文献
16.
A new type of water‐soluble single‐walled carbon nanotubes (SWNTs) was synthesized by grafting of dodecyl quaternary ammonium bromides. Results of Fourier transform infrared and proton nuclear magnetic resonance spectroscopic analyses confirmed the successful synthesis. Water‐soluble performance of functionalized SWNTs, i.e. N+‐SWNTs, has been studied in terms of solubility and stability. It was found that the solubility could reach up to 110 mg.l?1 and as‐prepared solution possesses a good stability over the PH range of 6.87–11.25. Based on these properties, one of the important applications of N+‐SWNTs was demonstrated to prepare poly(vinyl alcohol) (PVA) composites. Owing to critical issues of uniform dispersion and enhanced interfacial PVA‐nanotube interaction having been simultaneously resolved to a reasonable extent, the composite film with only 0.3 wt% N+‐SWNTs showed an increase of 33% and 32% in tensile strength and Young's modulus, respectively, over neat PVA film. Moreover, a high optical quality and slightly increased glass transition temperature were also observed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献