共查询到19条相似文献,搜索用时 140 毫秒
1.
采用胶晶模板法制备出具有三维多孔结构的纳米CoFe2O4。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N2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CoFe2O4和球形纳米CoFe2O4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CoFe2O4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CoFe2O4,达到55.646 m2·g-1。DSC测试结果表明:多孔纳米CoFe2O4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CoFe2O4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CoFe2O4更高的催化活性。此外,对多孔纳米CoFe2O4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
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CoFeO纳米阵列催化剂的费托合成性能研究 《燃料化学学报》2017,45(9):1082-1087
通过可控的水热生长方法和钴铁碳酸根氢氧根水合物的焙烧在泡沫铁上制备了CoFe2O4纳米阵列催化剂。通过粉末X射线衍射,扫描电镜和电感耦合等离子体发射光谱表征了CoFe2O4纳米阵列的晶相,结构和组成。制备的催化剂被用于费托合成性能研究。CoFe2O4纳米阵列催化剂在5L/(g·h)的空速下具有69%的转化率,并且其性能优于粉体催化剂。 相似文献
3.
采用共沉淀法制备了CuGa2O4纳米材料,并利用水热法制备了一系列WS2/CuGa2O4复合材料。结合X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)等对制备的材料进行了物相组成、表面形貌以及元素价态的分析。研究了WS2的复合量对CuGa2O4材料检测乙醇气体敏感性能的影响。实验结果表明,当WS2与CuGa2O4质量比为1%时,该复合材料制备的传感器在室温下对100μL·L-1乙醇气体表现出345.3的灵敏度,响应时间和恢复时间分别为184和69 s,且最低检测限为0.1μL·L-1。 相似文献
4.
采用静电纺丝法成功制备了La3+掺杂CaFe2O4材料。通过X射线衍射、扫描电子显微镜和X射线光电子能谱对La3+掺杂CaFe2O4材料的结构和形貌进行了表征。随后,研究了La3+的掺杂量(质量分数)对CaFe2O4气敏性能的影响。研究表明,3%La3+掺杂CaFe2O4材料在室温下对100μL·L-1甲醛的响应最高(Ra/Rg=14.1)。更为重要的是,对甲醛的最低检测限低至0.1 nL·L-1,并且响应/恢复时间仅为4.3 s/8.4 s。 相似文献
5.
通过原位共沉淀法可控制备了系列直接Z型MIL-100(Fe)/Bi OBr异质结。使用粉末X射线衍射(PXRD)、傅里叶红外变换(FTIR)光谱、紫外可见漫反射光谱(UV-Vis DRS)、扫描电镜(SEM)、高倍透射电镜(HRTEM)以及X射线光电子能谱(XPS)对MIL-100(Fe)/Bi OBr异质结晶体结构、微观形貌、光学性能、化学组成进行表征。以低功率发光二级管可见光为光源,探究了MIL-100(Fe)/Bi OBr异质结光芬顿降解磺胺甲恶唑(SMX)性能。最佳反应体系MB-7/Vis/H2O2(MB-7是MIL-100(Fe)质量为Bi OBr质量的70%时制备的样品)在光源照射70 min后可降解99.8%SMX(5 mg·L-1)。同时,还考察了H2O2浓度、催化剂投加量、p H值以及无机阴离子对MB-7/Vis/H2O2降解SMX影响。MB-7/Vis/H2O2能够在经过... 相似文献
6.
本研究使用低温溶胶凝胶自燃法制备了不同载体负载的CuMn2O4/MO2(M=Mn、Ti、Ce)催化剂,并对其同时去除甲苯和NOx的性能进行了评价。结果表明,CeO2载体的加入可显著缓解CuMn2O4上甲苯氧化与NH3-SCR的相互抑制,因此,CuMn2O4/CeO2催化剂表现出最优异的甲苯与NOx同时去除效率。通过BET、XRD、NH3-TPD、O2-TPD及结合XPS与in-situ DRIFTs对催化剂的物化性质及CuMn2O4同时去除甲苯与NOx的反应机理进行了分析。结果表明,CeO2的引入提高了催化剂中Mn4+/Mnn+的占比,促使CuMn 相似文献
7.
浸渍法制备了一系列V2O5-CuO/TiO2催化剂,考察中低温(200~300℃)条件下,以氨为还原剂选择性催化还原NOx的活性,并利用比表面积及微孔孔隙分析仪(BET)、X射线衍射(XRD)对催化剂进行微观表征和分析。结果表明,500℃焙烧的2V16Cu/TiO2催化剂展示了最佳的中低温催化活性和较宽的活性温度范围,在空速6.0×104 h-1、225℃条件下,NOx转化率达97.3%,250℃时达到100%,温度升至300℃,催化活性仍保持在100%。XRD结果表明,随着Cu负载量的增加,逐渐显现CuO的特征峰。结合活性评价数据说明,CuO是VCu/TiO2催化剂的主要活性组分之一,是降低SCR催化反应温度的重要因素。BET结果表明,CuO的负载对钒钛催化剂的表面结构有较大影响。耐硫性实验结果表明,添加钒氧化物制备的2V16Cu/TiO2催化剂的抗硫性能有所改善。 相似文献
8.
采用水热法合成了Ce0.8Zr0.2O2固溶体,再经浸渍法负载活性组分制备了CuO/Ce0.8Zr0.2O2催化剂,考察了柠檬酸量对Cu O/Ce0.8Zr0.2O2催化剂结构、性质及其催化水气变换反应制氢性能的影响。结果表明,不同柠檬酸量制备的CuO/Ce0.8Zr0.2O2催化剂的催化活性主要与Cu比表面积、还原性能及Ce0.8Zr0.2O2固溶体与Cu O之间的相互作用有关。其中,柠檬酸浓度为0.04 mol/L所制备的催化剂具有较大的Cu比表面积,较低的Cu O还原温度和较强的Ce0.8Zr0.2O2固溶体与CuO之间的相互作用,在水气变换制氢过程中具有较高的CO转化率,表现出了较好的催化... 相似文献
9.
采用自制的比表面积为349 m2/g的纳米膜γ-Al2O3为载体,用等体积浸渍法制备了Ni-Pt/γ-Al2O3催化剂,采用比表面积测定、X射线衍射、扫描电镜和透射电镜等手段对所制备的催化剂进行了表征。利用微型连续管式反应器与气相色谱联用装置,考察了Ni-Pt/γ-Al2O3催化剂对甲基环己烷(MCH)气相脱氢的催化性能。结果表明,使用20%Ni-0.5%Pt/γ-Al2O3催化剂,在反应温度350℃,混合进样体积空速252 h-1条件下,甲苯转化率达到96.99%,选择性接近100%。 相似文献
10.
掺加Nd和K改性对CoO催化分解NO活性的影响 《燃料化学学报》2019,47(9):1120-1128
用水热法和共沉淀法分别制备了Nd-Co3O4催化剂,催化分解N2O。其中,水热法制备的Nd-Co3O4催化活性较高。在不同组成的Nd-Co3O4中,优化出了较高活性的0.01Nd-Co3O4催化剂,在其表面浸渍K2CO3溶液制备K改性催化剂(K/Nd-Co3O4)。用X射线衍射(XRD)、N2物理吸附、扫描电镜(SEM)、X射线光电子谱(XPS)、程序升温还原(H2-TPR)、O2程序升温脱附(O2-TPD)等技术表征催化剂结构。结果表明,Nd-Co3O4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-Co3O4催化剂上的N2O分解率超过90%,稳定性较好。 相似文献
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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
13.
Xiaoqing Yang Hualin Yang Huan Lu Haoxuan Ding Yanxin Tong Fei Rao Xin Zhang Qian Shen Jianzhi Gao Gangqiang Zhu 《物理化学学报》2022,37(10):2005008-0
This study concentrated on the production of a two-dimensional and two-dimensional (2D/2D) Ti3C2/Bi4O5Br2 heterojunction with a large interface that applied as one of the novel visible-light-induced photocatalyst via the hydrothermal method. The obtained photocatalysts enhanced the photocatalytic efficiency of the NO removal. The crystal structure and chemical state of the composites were characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that Ti3C2, Bi4O5Br2, and Ti3C2/Bi4O5Br2 were successfully synthesized. The experimental results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the prepared samples had a 2D/2D nanosheet structure and large contact area. This structure facilitated the transfer of electrons and holes. The solar light absorptions of the samples were evaluated using the UV-Vis diffuse reflectance spectra (UV-Vis DRS). It was found that the absorption band of Ti3C2/Bi4O5Br2 was wider than that of Bi4O5Br2. This represents the electrons in the Ti3C2/Bi4O5Br2 nanosheet composites were more likely to be excited. The photocatalytic experiments showed that the 2D/2D Ti3C2/Bi4O5Br2 composite with high photocatalytic activity and stability. The photocatalytic efficiency of pure Bi4O5Br2 for the NO removal was 30.5%, while for the 15%Ti3C2/Bi4O5Br2 it was 57.6%. Moreover, the catalytic reaction happened in a short period. The concentration of NO decreased exponentially in the first 5 min, which approximately reached the final value. Furthermore, the stability of 15%Ti3C2/Bi4O5Br2 was favorable: the catalytic rate was approximately 50.0% after five cycles of cyclic catalysis. Finally, the scavenger experiments, electron spin resonance spectroscopy (ESR), transient photocurrent response, and surface photovoltage spectrum (SPS) were applied to analyze the photocatalytic mechanism of the composite. The results indicated that the 2D/2D heterojunction Ti3C2/Bi4O5Br2 improved the separation rate of the electrons and holes, thus enhancing the photocatalytic efficiency. In the photocatalytic reactions, the photogenerated electrons (e−) and superoxide radical (·O2−) were critical active groups that had a significant role in the oxidative removal of NO. The in situ Fourier-transform infrared spectroscopy (in situ FTIR) showed that the photo-oxidation products were mainly NO2− and NO3−. Based on the above experimental results, a possible photocatalytic mechanism was proposed. The electrons in Bi4O5Br2 were excited by visible light. They jumped from the valence band (VB) of Bi4O5Br2 to the conduction band (CB). Then, the photoelectrons transferred from the CB of Bi4O5Br2 to the Ti3C2 surface, which significantly promoted the separation of the electron-hole pairs. Therefore, the photocatalytic efficiency of Ti3C2/Bi4O5Br2 on NO was significantly improved. This study provided an effective method for preparing 2D/2D Ti3C2/Bi4O5Br2 nanocomposites for the photocatalytic degradation of environmental pollutants, which has great potential in solving energy stress and environmental pollution. 相似文献
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采用水热-共沉淀法制备了一种新型的磁性AgI-BiOI/CoFe2O4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(Hg0)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/CoFe2O4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O2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CO32-和SO42-对脱汞效率有一定的抑制作用;当通入SO2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,SO2、NO和Hg0的最终氧化产物分别是SO42-、NO3-和Hg2+ 相似文献
15.
WANG Xin ZHUANG Linzhou JIA Yi ZHANG Lijie YANG Qin XU Wenjia YANG Dongjiang YAN Xuecheng ZHANG Longzhou ZHU Zhonghua BROWN Christopher L. YUAN Pei YAO Xiangdong 《高等学校化学研究》2020,36(3):479-487
Developing efficient catalysts toward both oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) is the core task for rechargeable metal-air batteries. Although integration of two active components should be an effective method to produce the bifunctional catalysts in principle, traditional techniques still can not attain fine tunable surface structure during material-hybridization process. Herein, we present a facile short-time in-situ argon(Ar) plasma strategy to fabricate a high-performance bifunctional hybrid catalyst of vacancy-rich CoFe2O4 synergized with defective graphene(r-CoFe2O4@DG). Reflected by the low voltage gap of 0.79 V in two half-reaction measurements, the striking capability to catalyze ORR/OER endows it excellent and durable performance in rechargeable Zn-air batteries, with a maximum power density of 155.2 mW/cm2 and robust stability(up to 60 h). Further experimental and theoretical studies validate its remarkable bifunctional energetics root from plasma-induced surface vacancy defects and interfacial charge polarization between DG and CoFe2O4. This work offers more opportunities for reliable clean energy systems by rational interfacial and defect engineering on catalyst design. 相似文献
16.
Peroxymonosulfate(PMS) has received increasing attention as viable technology for recalcitrant organics removal from polluted waters. Although promising, alternative heterogeneous catalysts with stable structure, strong hydrophilicity, environmental friendliness and excellent catalytic performance are highly desirable to facilitate the wide industrialization of PMS. In this work, Ni doped CoOOH catalyst was employed as PMS activator. Ni dopant had a significant influence on the morphology, structure and catalytic performance of CoOOH. NiojCoo.gOOH exhibited the best catalytic performance. Reaction rate ofNio.2Coo.8OOH was 2, 4, and 4.4 times that of CoOOH, CoFe2O4 and CO3O4, respectively. Moreover, Ni。2C00.8OOH/PMS system had potential application to organic pollutants and displayed a great catalytic activity over a broader pH value(e.g., 4-10). More importantly, Ni doping accelerated the transfonnation of Co(Ⅲ) and Co(Ⅱ) and formed active species CoOH^+ and NiOH^+ which were responsible to the enhancement of PMS activation.OH, SO4^-:O2^- and 1^O2 were detected, indicating both non-radical and radical processes in the Nio.2Coo.8OOH/PMS system. These findings provide a promising alternative to mixed-metal oxyhydroxides catalysts for PMS activation, demonstrating a great potential in environmental remediation and wastewater treatment. 相似文献
17.
Cu/Co/Mn基氧载体释氧动力学及机理研究 总被引:2,自引:1,他引:1
以溶胶凝胶法制备了CuO/CuAl2O4、Co3O4/CoAl2O4以及Mn2O3/Al2O3氧载体,在流化床反应器中CO2气氛下研究了不同温度下氧载体释氧特性,并通过分析得到各氧载体的释氧动力学机理函数、活化能及指前因子等重要参数。释氧过程中,氧载体CuO/CuAl2O4中CuO、CuAl2O4均为活性相,释氧后转化为Cu2O及CuAlO2,而Co3O4/CoAl2O4及Mn2O3/Al2O3中CoAl2O4和Al2O3均为惰性相,仅有Co3O4和Mn2O3参与释氧并分别转化为CoO和Mn3O4。三种氧载体的释氧过程均可由成核-核生长机理描述,释氧初期氧载体经化学反应形成新的活性核心,随后活性核心聚集形成还原态的氧载体团簇。各氧载体释氧的机理函数G(x)有不同的表达式,CuO/CuAl2O4、Co3O4/CoAl2O4、Mn2O3/Al2O3释氧的活化能E分别为226.37、130.06和65.90 kJ/mol,相对应的指前因子A分别为2.99×106、4.96×103和27.37 s-1。 相似文献
18.
采用共沉淀法制备了高比表面积的MnxCo3−xO4球形催化剂,研究了NH3选择性催化还原NOx性能。Mn-Co金属氧化物具有尖晶石结构,随着Co含量的增加,晶体结构由四方相转变为立方相。高浓度的表面活性氧物种和变价元素的强有效电子转移(Co3+ + Mn3+ ↔ Co2+ + Mn4+)有利于提高MnxCo3−xO4 (x = 1.0、1.5、2.0)尖晶型石催化剂的氧化还原能力,催化剂表面的Mn富集作用形成了氧缺陷结构和丰富的表面活性位点,进一步促进SCR脱硝反应,呈现出优异的催化性能。Cotet(CoMn)octO4晶体结构中,Mn离子(Mn3+和Mn4+,以三价锰为主)和部分Co离子被配置到八面体中心,这些物种作为活性位点存在着较强的电子转移交互作用,该构型对促进低温脱硝活性和保护活性位点耐受SO2毒害具有重要的意义。Mn-Co尖晶石表面的NH3-SCR脱硝反应过程主要遵循Eley-Rideal反应机理,即吸附态NH3与气态NO (或NO2)的反应路径。随着反应温度的增加,反应生成的NH4NO3中间体很可能转化为NH4NO2物种,进而分解为N2,提高了催化剂的氮气选择性。 相似文献