共查询到20条相似文献,搜索用时 31 毫秒
1.
Mohammad Hossein Sheikh-Mohseni Sajjad Sedaghat Pirouz Derakhshi Aliakbar Safekordi 《中国化学工程学报》2020,28(10):2555-2565
In this work, synthesis of Ni nanoparticles was carried out successfully by water extract of Allium jesdianum as a biochemical reducing agent in the presence of montmorillonite clay (MMT) as a natural solid support for the first time. Then the electrochemical activity of the synthesized nanocomposite was investigated in methanol electrocatalytic oxidation. MMT with high cation exchange capacity and nano layer structure was exposed to ion exchange conditions in nickel solution. Then Ni2+ ion exchanged form was used in this process as a source of ions and also capping agent. Water extract of Allium jesdianum used as a reducing agent due to abundant availability of phenolic and flavonoid contents. The synthesized Ni/MMT nanocomposite was characterized using UV–Vis spectroscopy (UV–Vis), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM) and Energy-dispersive X-ray spectroscopy (EDX). The surface of prepared modified electrode has been characterized using SEM to evaluate the morphology, showing uniform dispersion of Ni nanoparticles with mean diameter of 12 to 20 nm. The modified carbon paste electrode was then used in methanol electrocatalytic oxidation reaction. Methanol oxidation on the proposed modified electrode surface occurs at 0.6 V and 0.3 V in alkaline and acidic medium respectively. Also, the results showed the better performance of modified electrode toward methanol electrocatalytic oxidation in comparison with carbon paste electrode that is modified by ion exchanged MMT. Charge transfer coefficients and apparent charge transfer rate constant for the modified electrode in the absence of methanol in alkaline medium were respectively found as: αa = 0.53, αc = 0.37 and ks = 1.6 × 10−1 s−1. Also, the average value of catalytic rate constant for the electrocatalytic oxidation of methanol by the prepared nano-catalyst was estimated to be about 0.9 L·mol-1·s-1 by chronoamperometry technique. The prepared electrode was also effective for electrocatalytic oxidation of ethanol and formaldehyde in alkaline medium. 相似文献
2.
The different electrocatalytic reactors could be constructed for the electrocatalytic oxidation of 2,2,3,3-tetrafluoro-1-propanol(TFP) with two typical MnO_x/Ti electrodes, i.e.the electrocatalytic membrane reactor(ECMR) with the Ti membrane electrode and the electrocatalytic reactor(ECR) with the traditional Ti plate electrode.For the electro-oxidation of TFP, the conversion with membrane electrode(70.1%) in the ECMR was 3.3 and 1.7 times higher than that of the membrane electrode without permeate flow(40.8%) in the ECMR and the plate electrode(21.5%) in the ECR, respectively.Obviously, the pore structure of membrane and convection-enhanced mass transfer in the ECMR dramatically improved the catalytic activity towards the electro-oxidation of TFP.The specific surface area of porous electrode was 2.22 m~2·g~(-1).The surface area of plate electrode was 2.26 cm~2(1.13 cm~2× 2).In addition, the electrochemical results showed that the mass diffusion coefficient of the MnO_x/Ti membrane electrode(1.80 × 10~(-6) cm~2·s~(-1)) could be increased to 6.87 × 10~(-6) cm~2·s~(-1) at the certain flow rate with pump, confirming the lower resistance of mass transfer due to the convection-enhanced mass transfer during the operation of the ECMR.Hence, the porous structure and convection-enhanced mass transfer would improve the electrochemical property of the membrane electrode and the catalytic performance of the ECMR,which could give guideline for the design and application of the porous electrode and electrochemical reactor. 相似文献
3.
This study investigated catalytic decomposition and mass transfer of aqueous ozone promoted by Fe-Mn-Cu/γ-Al2O3 (Cat) in a rotating packed bed (RPB) for the first time. The results showed that the value of the overall decomposition rate constant of ozone (Kc) and overall volumetric mass transfer coefficient (KLa) are 4.28×10-3 s-1 and 11.60×10-3 s-1 respectively at an initial pH of 6, β of 40, of 60 mg·L-1 and QL of 85 L·h-1 in deionized water, respectively. Meanwhile, the Kc and KLa values of Fenhe water are 0.88×10-3 s-1 and 2.51×10-3 s-1 lower than deionized water, respectively. In addition, the Kc and KLa values in deionized water for the Cat/O3-RPB system are 44.86% and 47.41% higher than that for the Cat/O3-BR (bubbling reactor) system, respectively, indicating that the high gravity technology can facilitate the decomposition and mass transfer of ozone in heterogeneous catalytic ozonation and provide some insights into the industrial wastewater. 相似文献
4.
5.
主要研究了不锈钢/PbO2电极和掺杂的不锈钢/Fe-PbO2电极的制备,用其对有机废水的处理效果及影响因素来评价该电极的性能。实验结果表明:采用恒流阳极电沉积技术制备的PbO2电极,掺杂和不掺杂铁的电极主要成分都是β-PbO2;两电极外观都没有明显的裂纹等缺陷,掺杂铁的二氧化铅镀层颗粒大小镶嵌,很好地清除了内应力,保证了基材与镀层不易脱落,未掺杂铁的二氧化铅镀层颗粒细小、均匀,内应力有些大;将Fe(NO3)2添加至电沉积溶液中,致使PbO2电沉积层的析氧电位向正方向移动,改善了PbO2电极的电催化活性,以至于更有利于氧化降解有机物。用改性的Fe-PbO2电极和常规的PbO2电极分别降解初始浓度相同的邻苯二酚和苯酚有机物废水,改性的Fe-PbO2电极对苯酚和邻苯二酚的去除率均高于常规的PbO2电极。掺杂铁的二氧化铅电极较未掺杂电极有更好的电催化活性,更高的析氧电位,更适宜于用作电催化阳极。 相似文献
6.
The hexagonal closed packed (hcp) nanocrystalline nickel (Ni), with an average diameter of 9.7 ± 2.27 nm was deposited uniformly on composite graphite (CG) by the rapid scanning (6,500 mVs–1) voltammetry technique. The hcp‐nano Ni‐modified CG electrode was investigated for the catalytic oxidation of methanol in alkaline medium through the formation of NiOOH. A high anodic current was obtained at peak potential of +570 mV vs Ag/AgCl. Both the scan rate and the methanol concentration affected the oxidation of methanol. The results showed that catalytic activity had increased with decrease in Ni particle diameter. It was also shown that the hcp‐nano Ni/CG modified electrode was the most efficient catalyst in the oxidation of methanol. 相似文献
7.
Bay Van Tran Son Ich Ngo Young-Il Lim Keon Bae Dong Hyun Lee Kang-Seok Go Nam-Sun Nho 《中国化学工程学报》2021,33(5):190-202
A multiphase computational fluid dynamics(CFD) model coupled with the population balance equation(PBE) was developed in a homogeneous air–kerosene bubble column under elevated pressure(P). The specific pressure drop(DP/L), gas holdup(a_G), and Sauter mean diameter(d_(32)) were experimentally measured in the bubble column with 1.8 m height and 0.1 m inner diameter, which was operated at a superficial gas velocity of 12.3 mm·s~(-1), and P = 1–35 bar(1 bar = 10~5 Pa). A modified drag coefficient model was proposed to consider the effect of bubble swarm and pressure on hydrodynamics of the bubble column.The Luo breakage model was modified to account for liquid density, viscosity, surface tension and gas density. The DP/L, a_G, and d_(32) obtained from the CFD model were compared with experimental data,and the gas density-dependent parameters of the CFD model were identified. With increasing P from 1 to 35 bar, the aGvaried from 5.4% to 7.2% and the d_(32) decreased from 2.3 to 1.5 mm. The CFD-PBE model is applicable to predict hydrodynamics of pressurized bubble columns for gas–organic liquid in the homogeneous regime. 相似文献
8.
在锂离子电池电极材料研究中,第一性原理计算能在理论上协助解释实验结果,为材料的合成和性能改进提供理论依据。目前第一性原理计算在锂离子电池电极材料中的应用主要集中在正极材料磷酸铁锂和层状氧化物LiMO2(M=Ni, Co, Mn, Al等)材料中,对热门三元材料,特别是三元材料改性前后界面结构变化的研究较少。围绕密度泛函理论,综述了其在电极材料工作电压、电子传导性和离子扩散性、结构稳定性、储锂容量的计算以及热力学性能预测及解释等方面的应用,对较为集中的研究方向的进展进行阐述和总结,为用第一性原理进一步研究LiNi x Co y Mn1- x - y O2复合材料提供借鉴。 相似文献
9.
A nanocomposite based on layered double hydroxides (LDHs) and gold nanoparticles (AuNPs) was prepared via hydrothermal treatment followed by a reduction procedure. The AuNPs were obtained in Mg-Al LDHs, and they maintained good stability. The electrocatalytic activities of AuNPs/LDH-modified glassy carbon electrodes for methanol oxidation in alkaline medium were investigated in detail. Under the same conditions, the modified electrode exhibited higher electrocatalytic activity than both the pure AuNPs-modified electrode and LDH-modified electrode. The role of the AuNPs and LDHs in this composite system was explored by cyclic voltammetry and chronoamperometry, respectively. Further studies demonstrated that the promoting effect of LDHs could be due to its strong adsorption and partly to the discharge of OH− during methanol oxidation. This work indicates that LDHs is expected to be a good supporting material in the development of methanol anode catalysts. 相似文献
10.
M. G. Hosseini M. Abdolmaleki V. Daneshvari Esfahlan 《Journal of Porous Materials》2017,24(2):305-313
The nanostructured Co/Co–Ni–Pt catalyst were synthesized by electrodeposition process and galvanic replacement reaction. The alloy prepared on a copper electrode (Cu/Co/Co–Ni–Zn) was dipped in platinum containing alkaline solution to produce a porous Cu/Co/Co–Ni–Pt catalyst. The catalyst was characterized by energy dispersive X-ray and scanning electron microscopy techniques and its electrocatalytic properties were evaluated using cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry techniques. The results showed that the Co/Co–Ni–Pt coatings are porous, and composed of discrete Pt nanoparticles with the crystallite size of about 66 nm. It was shown from cyclic voltammograms in alkaline solutions that the oxidation current of methanol on the nanostructured Cu/Co/Co–Ni–Pt electrode was much higher than that on flat platinum. Electrochemical impedance spectra on the Co/Co–Ni–Pt electrode reveal that the charge transfer resistance decreases with the increase of anodic potentials. All results show that the Co/Co–Ni–Pt catalysts can be potential anode catalysts for the direct methanol fuel cell. 相似文献
11.
Ni–Al–NO3 layered double hydroxides (LDH) are electrodeposited on the glassy carbon (GC) electrodes and the electrocatalytic activities of the modified electrodes toward methanol oxidation are studied in detail by cyclic voltammetry and chronoamperometry. Various factors affecting the electro-oxidation of methanol are investigated for optimizing the electrocatalytic properties and making the mechanism clearly such as methanol concentration, scan rate, KOH concentration, Ni:Al ratio of Ni–Al LDH used. The results show that Ni–Al–NO3 LDH exhibit higher electrocatalytic activity for methanol oxidation and better stability than that of Ni(OH)2 prepared under the same condition. The LDH with Ni:Al ratio of 3:1 display a good electrocatalytic activity for methanol oxidation in 0.5 M KOH. The mechanism of methanol oxidation on Ni–Al LDHf/GC electrode is also proposed according to the experimental results, involving in both a chemical oxidation via Fleischmann's mechanism and a direct electro-oxidation on the Ni3+ oxide surface. 相似文献
12.
The use of silicon microchannel plates (MCP) modified with nickel–palladium (Ni–Pd) nanoparticles by electroless plating was studied for the electrocatalytic oxidation of methanol and ethanol by cyclic voltammetry and chronoamperometry in alkaline media. The electrocatalyst was characterized by EDS, SEM and cyclic voltammetry, and the effective parameters on electrocatalytic oxidation of the alcohol, i.e. the concentration of KOH and alcohol, medium temperature and working potential limit in anodic direction were investigated. The modified electrode shows a superior electrooxidation performance with the operating temperature increasing and a strong current response to methanol and ethanol even during long-term oxidation of alcohol. All results show that the Ni–Pd/Si–MCP nanocomposite electrode is very attractive for integrated fuel cell applications. 相似文献
13.
The synthesis, physical characterization, decontamination and some electrocatalytic properties of PtRu nanoparticles prepared using the microemulsion method are reported. The nanoparticles are synthesized by reduction with sodium borohydride of H2PtCl6 and RuCl3 in a water-in-oil microemulsion of water/polyethylenglycol-dodecylether (BRIJ® 30)/n-heptane. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and energy dispersive analysis by X-rays (EDAX) experiments were carried out to characterize the single and bimetallic nanoparticles obtained. Cyclic voltammograms (CV) of clean nanoparticles were obtained after a controlled decontamination procedure of their surfaces. CO adsorption–oxidation and methanol electrooxidation were used as test reactions to check the electrocatalytic behaviour of the bimetallic nanoparticles. Pt80Ru20 (nominal atomic composition) nanoparticles are the best electrocatalyst for both COad and methanol oxidation. All these results show that the microemulsion method can be used to produce bimetallic nanoparticles in a very easy way. The method can be very easily scaled-up for industrial use. 相似文献
14.
Au/Pb(ad) electrodes were prepared by the underpotential deposition of lead ions at various potentials in 1 M HClO4 solution containing Pb(CH3COO)2 at concentrations of about 1 × 10−2, 1 × 10−4 and 1 × 10−6 M, respectively. The best preparation condition was selected. These electrodes, modified by foreign metal atom were used to catalyze the reduction of nitrate in concentrated alkaline solution, and exhibited efficient electrocatalytic activity for this system. 相似文献
15.
固体氧化物电解池可以清洁、高效地将电能和热能转化为化学能,在新能源领域具有广阔的应用前景。La0.75Sr0.25Cr0.5Mn0.5O3-δ(LSCM)具有较好的高温稳定性,但离子电导率相对较低,在电解过程中电催化性能不足。本文将LSCM与具有较高离子导电性的Ce0.8Gd0.2O2-δ(GDC)复配构造复合电极,并以共负载的形式在复合电极中浸渍纳米Ni、Cu金属催化剂提高电极的水蒸气吸附和转化能力,Ni、Cu共负载能够同时保留单一Ni或Cu负载对电极电解机制的改善。结果表明,Ni、Cu共负载相比于单一Ni或Cu负载电极在还原性气氛下具有更高的电化学性能,在还原性气氛和800℃工作温度下,镍铜质量比2∶8的负载电极在-0.1 V过电位下的电流密度可达到2.36 A·cm-2,极化阻抗为0.92Ω·cm2。 相似文献
16.
通过水热法制备得到TiO2改性石墨烯复合材料(RGO/TiO2),考察了其形貌结构和电化学性能。将其组装成电极,对比未改性石墨烯(RGO)电极和RGO/TiO2电极的电吸附NH4+性能。重点考察外加电压、循环流速、初始浓度等工艺参数对RGO/TiO2电极电吸附NH4+的影响,并对其电吸附NH4+特性和对模拟实际含NH4+废水深度脱NH4+效果进行研究。结果表明:RGO/TiO2复合材料具有三维孔洞结构,比表面积为382.08 m2·g-1,比电容量在扫速为0.01 V·s-1时达到325.80 F·g-1,优于RGO材料。RGO/TiO2电极的初次电吸附量较RGO电极提升了28.3%,循环再生吸附10次后,RGO/TiO2电极的NH4+吸附量仅降低了5.87%,循环再生吸附性能优于RGO电极。外加电压2.0 V、循环流速35 ml·min-1和NH4+初始浓度1.0 mmol·L-1为RGO/TiO2电极的最佳NH4+电吸附条件。RGO和RGO/TiO2电极电吸附NH4+过程符合准一级动力学模型和Freundlich等温吸附模型,电吸附NH4+为非均匀表面的多层吸附行为,以物理吸附为主。RGO/TiO2电极4级串联时对模拟实际含NH4+炼油净化水的去除率达到86.84%。 相似文献
17.
Removal of ammonium ions in wastewater by electrosorption with TiO2 modified graphene electrode
下载免费PDF全文
![点击此处可从《化工学报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this study, the TiO2 modified graphene composite material (RGO/ TiO2) was prepared by hydrothermal method, and its morphological structure and electrochemical properties were investigated. Then RGO/TiO2 material was assembled into electrode, and NH4+ ions electrosorption efficiencies of unmodified graphene (RGO) electrode and the RGO/TiO2 electrode were compared. The effects of applied voltage, circulating velocity and initial concentration on NH4+ ions electrosorption by RGO/TiO2 electrode were investigated. The characteristics of NH4+ ions electrosorption and the effect of advanced NH4+ ions removal from simulated actual wastewater containing NH4+ ions were also studied. The results showed that the RGO/TiO2 composite material had a three-dimensional pore structure with specific surface area of 382.08 m2·g-1 and specific capacitance of 325.80 F·g-1 at a scan rate of 0.01 V·s-1, which were better than those of the RGO material. The initial adsorption capacity of RGO/TiO2 electrode was 28.3% higher than that of RGO electrode. After 10 cycles of regeneration adsorption, the adsorption capacity of NH4+ ions of RGO/TiO2 electrode only decreased 5.87%, and its cyclic regeneration adsorption property was better than that of RGO electrode. In addition, the applied voltage 2.0 V, circulating velocity 35 ml·min-1 and initial concentration 1.0 mmol·L-1 were the optimal NH4+ ions electrosorption conditions for RGO/TiO2 electrode. The electrosorption process of NH4+ ions by RGO and RGO/TiO2 electrodes was in accordance with the quasi-first-order kinetic model and the Freundlich isothermal adsorption model. The electrosorption of NH4+ ions was a multi-layer adsorption behavior on heterogeneous surface and physical adsorption was the dominant. When the RGO/TiO2 electrode was connected in 4-stage series, the removal efficiency of simulated actual NH4+ refining purified water reached 86.84%. 相似文献
18.
以Fe(NO3)3、煤矸石和NaOH为原料,采用沸腾回流法制得了一系列不同质量比的α-Fe2O3/煤矸石复合光催化剂。采用场发射扫描电子显微镜(FESEM)、X射线衍射仪(XRD)及紫外-可见漫反射光谱(UV-Vis DRS)等多种手段对产物做了表征。以五氯酚为目标降解物,考察了模拟太阳光照下样品的光催化效果。结果表明,将球形α-Fe2O3负载于改性煤矸石表面可有效提高其光催化活性,且α-Fe2O3/煤矸石复合光催化剂的性能与α-Fe2O3的含量有关,当α-Fe2O3与煤矸石的质量比为30∶100时,样品的光催化效果最佳,180 min内即可将五氯酚降解完全。此外,α-Fe2O3/煤矸石复合光催化剂还具有可重复使用的特点。 相似文献
19.
An in situ infrared spectroscopic study was conducted to elucidate the reaction pathways for low-temperature methanol synthesis in a catalytic system composed of Ni(CO)4 and CH3OK (denoted as Ni(CO)4/CH3OK). The reaction was conducted in a liquid medium at 313–333 K with an initial pressure of 3.0 MPa. When CH3OK was added to Ni(CO)4 solution at 293 K, different carbonylnickelates, [Ni5(CO)12]2−, [Ni6(CO)12]2− and [Ni(CO)3(COOCH3)]−, were immediately formed from Ni(CO)4. The species and the composition of the carbonylnickel complexes varied with temperature. The variations in concentrations of methanol (MeOH) and methyl formate (MF) during the run, which were determined from their IR absorptions, indicated a pattern characteristic of consecutive reactions with MF as an intermediate. Thus, it was shown that methanol was produced through the carbonylation of MeOH to MF and the subsequent hydrogenation of MF to MeOH. Stable hydridocarbonylnickel anions, [HNi(CO)3]− and/or [HNi2(CO)6]−, were observed together with a small amount of Ni(CO)4 throughout the methanol synthesis. Since Ni(CO)4 alone showed no activity for the hydrogenation of MF, the hydridocarbonylnickel anions generated in the presence of CH3OK must be responsible for the reaction. The dual role of CH3OK in the catalytic system was stated. 相似文献
20.
Ammaru Ismaila Huanhao Chen Yan Shao Shaojun Xu Yilai Jiao Xueli Chen Xin Gao Xiaolei Fan 《中国化学工程学报》1982,28(9):2328-2336
Excess crude glycerol derived as a by-product from biodiesel industry prompts the need to valorise glycerol to value-added chemicals. In this context, catalytic steam reforming of glycerol (SRG) was proposed as a promising and sustainable alternative for producing renewable hydrogen (H2). Herein, the development of nickel (Ni) supported on ceria-modified mesoporous γ-alumina (γ-Al2O3) catalysts and their applications in catalytic SRG (at 550-750 °C, atmospheric pressure and weight hourly space velocity, WHSV, of 44,122 ml·g-1·h-1 (STP)) is presented. Properties of the developed catalysts were characterised using many techniques. The findings show that ceria modification improved Ni dispersion on γ-Al2O3 catalyst support with highly active small Ni particles, which led to a remarkable catalytic performance with the total glycerol conversion (ca. 99%), glycerol conversion into gaseous products (ca. 77%) and H2 yield (ca. 62%). The formation rate for H2 production (14.4 × 10-5 mol·s-1·g-1, TOF (H2) = 3412 s-1) was significantly improved with the Ni@12Ce-Al2O3 catalyst, representing nearly a 2-fold increase compared with that of the conventional Ni@Al2O3 catalyst. In addition, the developed catalyst also exhibited comparatively high stability (for 12 h) and coke resistance ability. 相似文献