High nitrogen carbon material with rich defects as a highly efficient metal-free catalyst for excellent catalytic performance of acetylene hydrochlorination

In this work,we developed a simple strategy to synthesize a carbon material with high nitrogen and rich carbon defects.Our approach polymerized diaminopyridine(DAP) and ammonium persulfate(APS).Following a range of different temperature pyrolysis approaches,the resulting rough surface was shown to exhibit edge defects due to N-doping on graphite carbon.A series of catalysts were evaluated using a variety of characterization techniques and tested for catalytic performance.The catalytic performance of the N-doped carbon material enhanced alongside an increment in carbon defects.The NC-800 catalyst exhibited outstanding catalytic activity and stability in acetylene hydrochlorination(C_2 H_2 GHSV=30 h~(-1),at 220℃,the acetylene conversion rate was 98%),with its stability reaching up to 450 h.Due to NC-800 having a nitrogen content of up to 13.46%,it had the largest specific surface area and a high defect amount,as well as strong C_2 H_2 and HCl adsorption.NC-800 has excellent catalytic activity and stability to reflect its unlimited potential as a carbon material.     

Highly sensitive C2H2 gas sensor based on Ag modified ZnO nanorods

The sliver (Ag) modified zinc oxide (ZnO) nanorods were successfully obtained with a simplified and environmentally friendly solvothermal method. Materials characterization indicated that the metallic Ag was located on the outside of ZnO nanorods after annealing. In comparison with ZnO nanorods, Ag modified ZnO (Ag–ZnO) nanorods exhibited a considerably enhanced response to C₂H₂. The response of the 3 at% Ag–ZnO based sensor operating at 175 °C is 539 (R_a/R_g), which is the highest value among all the sensors in detecting 100 ppm C₂H₂. The Ag–ZnO based sensors exhibited fast response speed, lower operation temperature and higher selectivity.     

基于综合判断的高抗内部缺陷分析与处理

分析了一起1000kV线路高抗乙炔含量异常故障,阐述了故障的原因和机理,给出了针对故障采取的消除缺陷的方法,介绍了后续带电检测的情况及结果。     

一种空分设备主冷液氧中乙炔含量的检测方法

介绍武钢氧气公司氢火焰气相色谱仪利用Al2O3柱测定空分设备液氧中乙炔含量的方法。通过PQ柱和Al2O3柱的比较、检测器的对比和对样品气的测定试验,确定采用Al2O3柱对空分设备主冷液氧中乙炔杂质含量的检测方法的准确性和可靠性。阐述试验条件和测定结果。     

Influence of the concentration of ethanol and the interaction of compounds in the pyrolysis of acetylene and ethanol mixtures

The pyrolysis of acetylene, ethanol and acetylene-ethanol mixtures in the 975-1475 K temperature range has been studied. The purpose of this work is to analyze the variation of soot and gas products coming from the pyrolysis of acetylene when adding increasing amounts of ethanol. Gas and soot products coming from the pyrolysis of 30,000 ppm of acetylene and different concentrations of ethanol (0-20,000 ppm) have been identified and quantified, and the influence of the amount of ethanol added has been analyzed. Analyses are supported on model calculations run with Chemkin using a detailed gas phase chemical kinetic mechanism, including subsets for acetylene and ethanol reactions and PAH formation and consumption reactions. In addition, the sum of the soot obtained from the individual pyrolysis of acetylene and ethanol is compared with the results coming from the pyrolysis of the corresponding acetylene-ethanol mixtures in order to analyze the interaction when they react jointly. Experimental results highlight the importance of the relative concentration acetylene/ethanol in the mixtures. Moreover, the results show that adding very small concentrations of ethanol, i.e. up to 600 times lower than acetylene concentration, leads to a diminution on the production of soot from the pyrolysis of acetylene.     

220kV变压器油纸电容式套管乙炔超标分析

介绍了一起变压器油纸电容式套管油色谱乙炔超标的故障情况,对故障产生的原因进行了分析,并提出了具体的防范措施。     

Effects of bimetallic catalyst composition and growth parameters on the growth density and diameter of carbon nanotubes

Multi-wall carbon nanotubes (MWNTs) were synthesized by catalytic decomposition of acetylene over Fe, Ni and Fe-Ni bimetallic catalysts supported on alumina under various controlled conditions. The growth density and diameter of CNTs were markedly dependent on the activation time of catalysts in H₂ atmosphere, reaction time, reaction temperature, flow rate of acetylene, and catalyst composition. Bimetallic catalysts were apt to produce narrower diameter of CNTs than single metal catalysts. For the growth of CNTs at 600 ‡C under 10/100 seem flow of C₂H₂/H₂ mixture, the narrowest diameter about 20 nm was observed at the reaction time of 1 h for 20Fe : 20Ni : 60Al₂O₃ catalyst, but at that of 1.5 h for 10Fe : 30Ni : 60Al₂O₃ catalyst. It was considered that the diameter and density of CNTs decreased with the increase of the growth time mainly due to hydrogen etching. The growth of CNTs followed the tip growth mode.     

Growth of carbon nanotubes with different morphologies by pyrolising acetylene

Abstract

Multiwalled carbon nanotubes (MWCNTs) with different morphologies have been prepared by pyrolysis of a mixture of acetylene-ferrocene over predeposited Co and Ni catalysts at 700°C. A high yield of carbon nanotubes with further purification have been obtained in the optimal conditions. The optimum synthesis parameters included synthesis temperature of 700°C, growth time of 30?min, flowrate of acetylene and hydrogen of 40 and 300?sccm respectively. Multiwall straight, curved, helically, coiled, planar-spiral and V-shaped nanotubes were found with diameters in the range of 10-70?nm and with lengths up to 5?μm. The morphology and structure features of the MWCNTs are characterised using scanning electron microscopy, transmission electron microscopy, energy dispersive spectra, Raman spectroscopy and thermogravimetry analyses.     

Spectroelectrochemical study of perchloroethylene reduction at copper electrodes in neutral aqueous medium

The potential-dependent chemical reaction of perchloroethylene (PCE) on copper in neutral noncomplexing aqueous media is explored by means of surface-enhanced Raman spectroscopy (SERS), linear sweep voltammetry and preparative electrolysis at controlled potential. Voltammetric peaks associated with copper oxide reduction in Na₂SO₄ solution in the presence and the absence of Cl⁻ are correlated with simultaneously acquired SER spectra. Perchloroethylene undergoes a dechlorination process at potentials at E ≤ −0.3 V vs. Ag/AgCl/KCl (3 M), as shown by the emergence of an intense CuCl stretching band at 290 cm⁻¹ and a CH stretching band together with the presence of Cl⁻ in the catholyte. In the potential region between 0 and −0.9 V vs. Ag/AgCl/KCl (3 M) a broad band assigned to CC structures is observed in the triple-bond region (∼1900 cm⁻¹, FWHM = 180 cm⁻¹). In addition, dichloroethylene (DCE) is detected (but not trichloroethylene (TCE)) in this potential region during preparative electrolysis. At potentials lower than −1 V vs. Ag/AgCl/KCl (3 M) carbon residues are the main product, detected on the copper surface by SERS (and confirmed by XPS), whereas in solution higher levels of dichloroethylene and trichloroethylene are detected with a DCE/TCE ratio below 1.