共查询到19条相似文献,搜索用时 265 毫秒
1.
利用化学沉淀法和溶胶凝胶法,通过两步法成功制备出含有尖晶石钴铁氧体和氧化铜的复合催化剂CoFe 2O 4/CuO,通过扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和X射线衍射(XRD)对制备出的CoFe 2O 4/CuO进行表征,探究不同高级氧化体系对磺胺甲恶唑(SMX)去除能力,考察过氧乙酸(PAA)浓度、催化剂投加量、水体中常见干扰物质(Cl -,HCO-3,SO 42-,HA)和不同自由基捕获剂对SMX去除的影响。分析结果表明CoFe 2O 4/CuO同时具有CoFe 2O 4与CuO的特征,对比单独CoFe 2O 4与CuO,CoFe 2O 4/CuO对PAA展现出极高的活化性能,在最佳反应条件下(催化剂投加量=20mg·L -1,c(PAA)=200μ... 相似文献
2.
采用胶晶模板法制备出具有三维多孔结构的纳米CoFe 2O 4。利用X射线衍射仪(XRD)、傅里叶变换红外(FT-IR)光谱仪、扫描电镜(SEM)、透射电镜(TEM)和N 2吸附-脱附对样品的晶型和形貌结构等进行表征,采用差示扫描量热法(DSC)对比研究多孔纳米CoFe 2O 4和球形纳米CoFe 2O 4对高氯酸铵(AP)的热分解性能的影响,并考察这两种催化剂对AP催化热分解的动力学参数。结果显示,制备出的多孔纳米CoFe 2O 4样品具有典型的尖晶石结构,孔径约200 nm;比表面积明显高于40 nm球形CoFe 2O 4,达到55.646 m 2·g -1。DSC测试结果表明:多孔纳米CoFe 2O 4的加入促进了AP的热分解,最高使AP的高温分解峰温降低91.46℃,能量释放最高达1120.88 J·g -1,是纯AP分解放热量的2.3倍;多孔纳米CoFe 2O 4具有较高的比表面积,能提高催化反应的接触面积,使AP的高温分解峰温度更低,反应活化能较小,从而表现出比球形纳米CoFe 2O 4更高的催化活性。此外,对多孔纳米CoFe 2O 4催化AP的热分解机理进行初步探索,纳米多孔催化剂对气态中间产物的作用促进了AP的热分解。 相似文献
3.
基于溶剂热合成体系,制备了不同形貌的Fe 3O 4微球和纳米片催化剂,考察了水热合成条件对Fe 3O 4晶粒形貌的影响,并研究了Fe 3O 4纳米催化剂的费托合成(F-T)性能。结果表明,成核和晶体生长速率是控制Fe 3O 4晶体形貌的关键。与传统的沉淀铁催化剂相比,Fe 3O 4纳米催化剂更容易还原和向活性相转变,因此,具有更高的F-T反应活性、低碳烯烃选择性及C 5+选择性;Fe 3O 4微球催化剂比纳米片催化剂更易维晶粒的稳定,具有更高的反应活性和稳定性。 相似文献
4.
以二元金属氧化物CoFe 2O 4为研究对象,通过次序模板法制备了CoFe 2O 4中空多壳层结构(HoMS)材料;对其形貌、结构进行了表征;考察了壳层结构与电化学性能之间的关系.电化学测试结果表明,双壳层-核CoFe 2O 4中空球具有最高的放电比容量(1354.4 mA·h/g)、优异的倍率性能和循环稳定性,其独特的结构优势和最优的空腔体积占有率使其在多次循环过程中能始终保持结构和电化学性质的稳定. 相似文献
5.
采用一步共沉淀法与Hummers法分别制备磁性纳米粒子CoFe 2O 4与氧化石墨烯(GO),在此基础上利用机械混合法自组装制备CoFe 2O 4@GO复合材料,将CoFe 2O 4@GO纳米粒子作为磁固相萃取剂,与高效液相色谱法联用对溶液中吡虫啉和毒死蜱进行分离分析。结果表明:在最佳实验条件下,吡虫啉和毒死蜱的线性范围分别为2~1000μg/L和4~2000μg/L,检出限分别为1.8和3.7μg/L,线性相关系数均大于0.999,加标回收率均大于85%,相对标准偏差(RSD)在3.7%~5.8%之间,为复杂溶液中吡虫啉和毒死蜱的分离分析提供了新方法。 相似文献
6.
为了研发高效、稳定的电解水催化剂,我们以氧空位和磷掺杂为基础,通过原位浸泡生长和两步热处理的方法,在泡沫铁上合成具有氧空位和磷掺杂的纳米花结构作为析氢反应(HER)和析氧反应(OER)双功能电催化剂。CoFe 2O 4已被报道为一种很有前途的OER和氧还原反应(ORR)电催化剂,然而CoFe 2O 4在HER中表现出电导率差、电催化反应慢的特性。CoFe 2O 4中氧空位(Ov)的形成可以有效调控催化剂表面的电子结构,有助于产生更多的缺陷和空位,从而提高OER的活性。随后,引入磷原子填充在空位中,制备的P-Ov-CoFe 2O 4/IF在碱性电催化测试中展现出优异的HER和OER性能,在10 mA·cm -2电流密度下HER和OER过电位仅为54和191 mV,Tafel斜率分别为57和54 mV·dec -1,并具有良好的循环稳定性。 相似文献
7.
从Pd纳米粒子出发制备具有核壳结构的Pd@SiO 2纳米粒子,并将其负载于不同形貌Al 2O 3载体上,制备出具有良好CO催化氧化活性的催化剂。以纳米球形Al 2O 3为载体时,Pd@SiO 2/Al 2O 3催化剂活性优于无核壳结构的Pd/Al 2O 3催化剂。将纳米Pd@SiO 2负载到球形和菱形Al 2O 3上,制备出Pd@SiO 2/Al 2O 3催化剂。结果表明:具有较大比表面积的Al 2O 3载体(球形)有利于Pd@SiO 2的分散,且SiO 2层可以抑制Pd粒子的团聚,能在一定程度上改善催化活性。而较小比表面积的载体(菱形)上出现了Pd@SiO 2的团聚,表现出较低的CO氧化活性,但在降低负载量后,CO氧化活性明显提高。该结果为推动新型热稳定、高效纳米三效催化剂的研发具有一定的启示意义。 相似文献
8.
采用水热-共沉淀法制备了一种新型的磁性AgI-BiOI/CoFe 2O 4复合材料光催化剂,考察了荧光灯辐照下光催化剂脱除模拟烟气中单质汞(Hg 0)的性能,研究了实验参数对脱汞性能的影响及反应产物。结果表明,AgI-BiOI/CoFe 2O 4光催化剂的热稳定性较差,当煅烧温度超过400 ℃时该光催化剂的化学成分会发生变化;随着催化剂用量、反应溶液pH值、反应溶液温度和烟气中O 2浓度的增加,脱汞效率先增加后不变或下降;反应溶液中存在的CO 32-和SO 42-对脱汞效率有一定的抑制作用;当通入SO 2时,脱汞效率急剧下降;而NO对脱汞效率的抑制作用相对较小。反应产物分析表明,SO 2、NO和Hg 0的最终氧化产物分别是SO 42-、NO 3-和Hg 2+ 相似文献
9.
通过调变HAuCl 4溶液的pH值和Au负载量,用沉积-沉淀法制备了一系列Au/Co 3O 4催化剂,并采用AES、BET、XRD、SEM、XPS和H 2-TPR等技术对催化剂的结构和组成进行了表征,考察了制备条件对其在有氧气氛中催化N 2O分解反应性能的影响规律,得到了催化剂最佳制备条件:HAuCl 4溶液pH值为9,Au负载量为0.29%。催化测试结果表明:虽然ZnCo 2O 4的催化活性优于Co 3O 4,但0.31%Au/ZnCo 2O 4的活性和稳定性低于0.29%Au/Co 3O 4。500℃、在含氧气氛中连续反应10 h, 两者均可完全分解N 2O,但在含氧、含水气氛中0.29%Au/Co 3O 4和0.31%Au/ZnCo 2O 4上的N 2O转化率分别为92%和63%。究其原因,发现Au/Co 3O 4中Au和Co组分间存在协同效应,而Au/ZnCo 2O 4中Au和Co组分间则没有协同效应。 相似文献
10.
浸渍法制备了催化剂V 2O 5-Sb 2O 3-TiO 2,考察了V 2O 5、Sb 2O 3负载量、pH值和焙烧温度对催化剂V 2O 5- Sb 2O 3-TiO 2低温氨选择性催化还原(SCR)NO活性的影响;同时,考察了催化剂V 2O 5-Sb 2O 3-TiO 2抗H 2O和SO 2毒化性能。结果表明,V 2O 5和Sb 2O 3负载量分别为5%和2%、焙烧温度为400℃、pH值为4时,催化剂SCR活性最好,反应温度220℃时,可达97%。Sb 2O 3的加入不仅能增强V 2O 5/TiO 2的催化活性,而且能明显提高催化剂的抗H 2O和SO 2毒化性能。SO 2、NO吸附暂态反应和TG-DTG测试表明,Sb 2O 3的促进机制主要是促进了催化剂在SO 2存在条件下对NO的吸附,同时,减弱了硫酸铵盐与催化剂之间的相互作用,硫酸铵盐更容易分解。 相似文献
11.
HeterojunctionFe_2O_3 nanoparticles(NPs), NiFe_2O_4 nanofibers(NFs), and CoFe_2O_4 NFs were synthesized by electrospinning and the subsequent thermal treatment processes. Characterization results indeed display the three-dimensional net-like textural structures of these as-electrospun spinel-type MFe_2O_4 NFs. The MFe_2O_4 NFs-based film configurations possess abundant micro/meso/macropores on their surface. These structures could afford more accessible transport channels for effective reduction of the mass transport resistance and improvement of the density of exposed catalytic active sites. All these advantages are responsible for the enhanced electro-catalytic performance of these MFe_2O_4 NFs in hydrazine oxidation. When used for hydrazine detection, CoFe_2O_4 NFs show the best catalytic efficiency.For example, the CoFe_2O_4 NFs possess a large sensitivity of 1327 mA cmà2(mmol Là1[à1in the linear range of 0.01 to 0.1 mmol Là1and 503 mA cmà2(mmol Là1)à1in the linear range of 0.1 to 11 mmol Là1, a response time of shorter than 3 s, good reproducibility and remarkable long-term stability. The superior catalytic efficiency, excellent stability, low cost, and ease of fabrication render CoFe_2O_4 NFs very promising materials in developing an electrochemical device that directly detects hydrazine. 相似文献
12.
通过金属点蚀技术制备了表面多孔形貌的羰基铁粉(PCIP),并采用共沉淀及原位聚合方法,将CoFe 2O 4与聚苯胺(PANI)负载于多孔羰基铁表面,得到具有电磁吸收性能的PCIP/CoFe 2O 4/PANI复合材料.通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、热重分析仪(TGA)及矢量网络分析仪(VNA)等对复合材料的形貌、成分和吸波性能进行了研究.结果表明,CoFe 2O 4/PANI团聚于PCIP表面,显著提升了复合材料电损耗能力,促进了低频电磁波的1/4波长干涉相消.当苯胺添加量为0.5 mL,复合材料在频率为5.7 GHz时,反射损耗达到-22.9 dB,低频吸波性能得到大幅提升.利用1/4波长干涉相消理论及电磁波界面反射模型对复合材料低频吸波性能提升的内在原因进行了分析. 相似文献
13.
Highly efficient Co 3O 4/TiO 2 monolithic catalysts with enhanced stability were in-situ grown on Ti mesh for CO oxidation,which could completely oxidize CO at 120℃.The comprehensive catalytic performance is competitive to some noble metal catalysts and conventional Co 3O 4 powder catalysts,which holds great potential toward industrial applications.Meanwhile,the in-situ synthesis strategy of Co 3O 4/TiO 2 monolithic catalysts on flexible mesh substrate in this work can be extended to the development of a variety of oxide-based monolithic catalysts towards diverse catalysis applications. 相似文献
14.
采用溶剂热法一步合成纳米尺寸CoFe 2O 4/GNS复合材料(直径约为15 nm),其颗粒尺寸均一,且均匀分散于石墨烯表面. 电化学测试结果表明,该复合物电极具有良好的循环和倍率性能,500 mA·g -1电流密度下100周期循环比容量稳定在709 mAh·g -1, 容量保持率高达95.8%;2 A·g -1电流密度,其比容量仍高达482 mAh·g -1. 相似文献
15.
We have investigated the continuous hydrothermal synthesis and crystallization of spinel CoFe 2O 4 via the reaction of ferric nitrate and cobalt nitrate with sodium hydroxide. The reaction was carried out in water at temperatures ranging from 475 to 675 K and pressures of 25 MPa. The relative solubility of the precipitating cations was found to play a critical role in attaining the correct product. It was found necessary to control pH and temperature in order to prevent premature precipitation of iron in the reactor. Two variations of the continuous hydrothermal technique were examined—cold mixing and hot mixing. The cold mixing experiments produced a product with less impurity than the hot mixing experiments. Furthermore, the cold mixing configuration was successful in producing uniform nanoparticles of CoFe 2O 4. A mechanism of particle formation was postulated involving the precipitation of metal hydroxides at ambient conditions, dissolution of the hydroxides as temperature is increased followed by rapid precipitation of metal oxides at elevated temperatures. The hot mixing experiments, on the other hand, simply involve the precipitation of metal oxides due to the addition of the hot hydroxide solution. In both cases, very fine particles of CoFe 2O 4 are produced in the range of the processing conditions investigated. 相似文献
16.
The solid–solid interactions between pure and alumina-doped cobalt and ferric oxides have been investigated using DTA, IR and XRD techniques. Equimolar proportions of basic cobalt carbonate and ferric oxide and different amounts of aluminum nitrate were added as dopant substrate. The amounts of dopant were 0.75, 1.5, 3.0 and 4.5 mol% Al 2O 3. The results obtained revealed that solid–solid interaction between Fe2O3 and Co3O4 takes place at temperatures starting from 700°C to produce cobalt ferrite. The degree of propagation of this reaction increases progressively as a function of precalcination temperature and Al2O3-doping of the reacting solids. However, the heating of pure mixed solids at 1000°C for 6 h. was not sufficient to effect the complete conversion of the reacting solids into CoFe2O4, while the addition of a small amount of Al2O3 (1.5 mol%) to ferric/cobalt mixed solids followed by precalcination at 1000°C for 6 h conducted the complete conversion of the reacting solids into cobalt ferrite. The heat treatment of pure and the 0.75 mol%-doped solids at 900 and 1000°C effected the disappearance of most of IR transmission bands of the free oxides with subsequent appearance of new bands characteristic for the CoFe2O4 structure. An increase in the amount of Al2O3 added from 1.5–4.5 mol% to the mixed solids precalcined at 1000°C led to the disappearance of all bands of free oxides and appearance of all bands of cobalt ferrite. The promotion effect of Al2O3 in cobalt ferrite formation was attributed to an effective increase in the mobility of the various reacting cations. The activation energy of formation (ΔE) of CoFe2O4 phase was determined for pure and doped solids. The computed values of ΔE were, respectively, 99.6, 87.8, 71.9, 64.7 and 48.7 kJ mol−1 for the pure solid and those treated with 0.75, 1.5, 3 and 4.5 mol% Al2O3. 相似文献
17.
用水热法和共沉淀法分别制备了Nd-Co 3O 4催化剂,催化分解N 2O。其中,水热法制备的Nd-Co 3O 4催化活性较高。在不同组成的Nd-Co 3O 4中,优化出了较高活性的0.01Nd-Co 3O 4催化剂,在其表面浸渍K 2CO 3溶液制备K改性催化剂(K/Nd-Co 3O 4)。用X射线衍射(XRD)、N 2物理吸附、扫描电镜(SEM)、X射线光电子谱(XPS)、程序升温还原(H 2-TPR)、O 2程序升温脱附(O 2-TPD)等技术表征催化剂结构。结果表明,Nd-Co 3O 4和K改性催化剂均为尖晶石结构;K改性弱化了催化剂表面Co-O键,有利于表面氧的脱除,提高了催化剂活性。有氧有水气氛350 ℃连续反应40 h,K/Nd-Co 3O 4催化剂上的N 2O分解率超过90%,稳定性较好。 相似文献
18.
采用固相反应法制备了具有尖晶石结构的LiMn_2O_4/TiO_2系列催化剂,探讨了TiO_2、Li/TiO_2、Mn/TiO_2、LiMn_2O_4及LiMn_2O_4/TiO_2等不同组成催化剂的甲烷氧化偶联反应性能,采用XRD、XPS、CO_2-TPD和H_2-TPR等表征方法对该系列催化剂进行了分析。结果表明,具有尖晶石结构的LiMn_2O_4化合物具有较高的甲烷氧化偶联催化活性,在775℃、0.1MPa、7200mL/(h·g),CH_4∶O_2(体积比)为2.5的条件下,甲烷转化率可达25.8%,C2选择性可达43.2%。TiO_2的存在不仅进一步提高了甲烷转化率和C2选择性,还有效抑制了甲烷完全氧化形成CO_2的过程。负载8%LiMn_2O_4的LiMn_2O_4/TiO_2催化剂性能达到最优,此时甲烷转化率达到31.6%,C2选择性为52.4%,CO_2选择性降低到26.3%。考察了不同焙烧温度对催化剂活性的影响,850℃为LiMn_2O_4/TiO_2催化剂的最佳焙烧温度。 相似文献
19.
对基于CoFe 2O 4载氧体的生物质化学链气化反应进行了热力学分析,研究了载氧体添加量、温度及水蒸气含量对气化反应特性的影响。同时应用热重分析仪对CoFe 2O 4和生物质的气化反应特性进行了实验研究,并利用XRD对反应前后载氧体的物相组成进行分析。热力学研究表明,CoFe 2O 4在气化反应中能够提供晶格氧,有效促进生物质气化,提高碳转化率。随着反应温度升高,合成气中H 2和CO的含量增加,CO 2的含量减少。随着水蒸气含量增加,H 2和CO 2含量会增加,CO含量减少。添加水蒸气能够提高合成气中H 2和CO的比值,改善合成气的品质。热重实验及XRD结果表明,钴优先于铁被还原,钴与铁存在协同作用,钴能够促进铁的进一步还原。随着载氧体添加量的增加,载氧体被还原的程度会降低,载氧体与生物质的最佳质量比为0.8。 相似文献
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