共查询到20条相似文献,搜索用时 171 毫秒
1.
以TiO 2、Al 2O 3、CeO 2和SiO 2为载体,采用浸渍法制备Pd基催化剂,并通过透射电镜(TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和电感耦合等离子体发射光谱(ICP-OES)等手段对催化剂的结构进行了详细表征.以Pd/TiO 2为催化剂,研究四溴双酚A(TBBPA)在阴极池的电催化还原.结果表明,悬浮体系中Pd基催化剂的催化活性远高于固定体系;与其他载体相比,Pd/TiO 2的电催化还原活性最高;反应过程符合Langmuir-Hinshelwood模型,受控于TBBPA在催化剂表面的吸附过程;随着恒定电流和Pd负载量的增大,TBBPA电催化还原反应的初活性呈现火山型变化规律;经过5次循环使用,Pd/TiO 2催化剂仍能够完全去除TBBPA,具有良好的稳定性. 相似文献
2.
载金催化剂可在温和条件下还原性降解环境中某些有毒有害污染物,并转化为低毒性、高附加值的物质,从而促进水体污染物化学资源转化和综合利用.本文设计制备Fe@CeO 2/CN双空腔核壳磁性载金椭球催化剂,用于还原降解水体中对硝基苯酚和染料污染物.该催化剂先制备Fe 2O 3@CeO 2梭型微粒内核,采用乙二胺介导的Stober扩展法在其表面合成SiO 2@RF复合物,经过碳化-水热蚀刻得到具有介孔碳氮壳层的Fe 2O 3@CeO 2/CN椭球;采用[Au(en) 2] 3+为金前驱体的沉积沉淀-还原气氛热处理法在上述椭球中构筑较好分散度超细纳米Au颗粒,同时Fe 2O 3转化为小体积Fe颗粒并形成内空腔,得到Fe@CeO 2-Au/CN双空腔核壳磁性椭球催化剂.该催化剂独特的结构特征和复合组分协同增强性效应使其在还原降解对硝基苯酚和染料... 相似文献
3.
采用沉淀陈化法制备了Ce∶Mn摩尔比为7∶3的CeO_2-MnO_x复合氧化物(Ce_(0.7)Mn_(0.3)O_x-PR),并使用X射线多晶粉末衍射(XRD)、场发射扫描电子显微镜(SEM)、高分辨率透射电子显微镜(TEM)、N_2吸附-脱附、X射线光电子能谱(XPS)和拉曼光谱(Raman)对所制备复合氧化物催化剂进行表征.结果表明,沉淀陈化过程可有效促进Ce_(0.7)Mn_(0.3)O_x-PR催化剂晶粒的生长,稳定催化剂的织构性质,且明显有利于Mn离子进入CeO_2晶格,减少MnO_x物种在催化剂表面的聚集.Mn离子进入CeO_2晶格可有效增加Ce_(0.7)Mn_(0.3)O_x-PR催化剂的晶格氧和氧空位,从而有助于其表现出更优异的碳颗粒催化氧化性能.所制备的Ce_(0.7)Mn_(0.3)O_x-PR催化剂对碳颗粒催化氧化的起燃温度(T_(50))为362℃、完全转化温度(T_(90))为419℃,该性能明显优于传统共沉淀法所制备的Ce_(0.7)Mn_(0.3)O_x-CP催化剂的性能(T_(50)、T_(90)分别为376℃、457℃). 相似文献
4.
以离子液体为氮源、磷源和氟源,采用一步水热法将N、P、F的3种元素掺杂到FeCo 2O 4中合成了NPF-FeCo 2O 4催化剂,用于活化过一硫酸氢钾(PMS)降解水中2,4-二氯苯氧乙酸(2,4-D).分别采用透射电子显微镜(TEM)、X射线光电子能谱(XPS)、傅立叶红外光谱(FTIR)、X射线衍射(XRD)对催化剂进行表征.实验结果表明,当催化剂投加量为0.1 g·L -1、PMS浓度为1 mmol·L -1时,反应30 min后2,4-D的去除率可达100%;初始pH值在3到9的范围内,体系对2,4-D的去除效果不受影响,水中低浓度的Cl -、HCO 3-和腐殖酸对反应有轻微的抑制.通过电子自旋共振波谱(EPR)测试结果显示,相较于FeCo 2O 4和NP-FeCo 2O 4催化剂,NPF-FeCo 2 相似文献
5.
以锐钛矿TiO 2(P25)为载体采用原位生长法负载锰氧化物制备了Mn/TiO 2催化剂,再以等体积浸渍-煅烧法对该催化剂掺杂氧化铈制备Ce(x)Mn/TiO 2-y催化剂用以烟气低温SCR脱硝.在固定锰负载量(质量分数为8%)的基础上,考察了铈掺杂量(铈锰摩尔比)、煅烧温度对催化剂SCR脱硝性能的影响.采用TEM、BET、XRD和XPS等手段表征了催化剂的理化结构特性.结果发现,当Ce/Mn的摩尔比例为1.0,煅烧温度为300℃时,Ce(1.0)Mn/TiO 2-300催化剂在150—300℃温度范围内、10500—27000 h -1的空速范围内,能够保持90%以上的NO转化率.理化性能分析结果表明,煅烧温度对催化剂的微观形貌影响显著,随着煅烧温度的升高,Ce(1.0)Mn/TiO 2-500催化剂活性物种颗粒集聚明显、比表面积降低,且锰氧化物价态分布偏向于低价态;铈的掺杂有助于Ce(1.0)Mn/TiO 2-300催化剂活性物种在载体表面的均匀分散,可以促进产生更多的Mn4+物种和更多的吸附氧,有利于催化剂低温SCR脱硝性能的提升. 相似文献
6.
以MoS 2为载体,通过水热法合成Fe 3O 4/MoS 2催化剂,采用X射线衍射、透射电子显微镜和X射线光电子能谱分析对材料进行表征,研究了Fe 3O 4/MoS 2/PMS体系中2,4-二氯苯氧基乙酸(2,4-D)的降解效率并探究了其反应机理.结果表明,以Fe 3O 4、MoS 2和Fe 3O 4/MoS 2为催化剂,30 min内2,4-D的去除率分别为31%、 20%和89%.表征结果发现,在MoS 2的存在下,Fe 3O 4表面的Fe(Ⅲ)还原为Fe(Ⅱ),Mo(Ⅳ)被氧化为Mo(Ⅵ),Fe 3O 4和MoS 2间的协同作用加强了PMS分解,提高了2,4-D去除效率.自由基淬灭实验表明,·OH、 SO<... 相似文献
7.
铬是污染性金属元素,铬含量是水质污染控制的一项重要指标,其中Cr(Ⅵ)的毒性最大,且易被人体吸收.本研究以水中的Cr(Ⅵ)吸附传质分离为目标,利用以铝为金属源水热法合成的铝基MOFs为前驱体,600℃煅烧后制备了多孔掺碳Al 2O 3吸附材料,利用现代分析技术对其进行微观结构表征,探究了其吸附作用能力与机制.研究结果表明,XRD、SEM、BET等表征手段证明了NH 2-MIL-53(Al)与多孔掺碳Al 2O 3结构的成功合成.前驱体NH 2-MIL-53(Al)和煅烧后的衍生物多孔掺碳Al 2O 3,在形貌上相似,且多孔掺碳Al 2O 3材料(180.24 m 2·g -1)的比表面积要大于NH 2-MIL-53(Al)(116.73 m 2·g -1).多孔掺碳Al 2 相似文献
8.
过氧化氢(H 2O 2)可广泛应用于市政饮用水、工业废水和城市污水的处理.然而,过氧化氢在储存和运输方面的风险(如腐蚀和爆炸)限制了其在分散式水处理中的应用.以二电子氧还原反应(2eORR)原位合成H 2O 2用于分散式水处理具有良好的应用前景.然而,未被催化的2e -ORR动力学缓慢、选择性差,不能满足大规模生产的要求.相比之下,杂原子掺杂碳材料具有良好的2e -ORR活性、选择性和稳定性.本文回顾了2e -ORR的反应机理和催化剂的改性原理,进一步描述了杂原子N、O、F掺杂碳材料的作用机理,并总结了几种具有优秀2e -ORR催化活性和选择性的掺杂结构.最后,对杂原子掺杂碳材料合成H 2O 2应用于水处理的未来发展进行了展望. 相似文献
9.
采用CTAB辅助水热法合成钼酸铋(Bi 2MoO 6,BMO)微球,并将其用于活化过一硫酸盐(PMS),在可见光下降解废水中的偶氮染料金橙Ⅱ(AO7).利用X射线衍射(XRD),傅里叶红外光谱仪(FT-IR),扫描电子显微镜(SEM),X射线能谱(XPS),透射电子显微镜(TEM)和紫外-可见漫反射光谱(UV-vis)对催化剂进行了表征,并通过降解实验测试其催化性能.结果表明,合成的催化剂具有良好的吸附、催化降解AO7的性能.在中性条件下,催化剂投加量0.3 g·L -1,AO7浓度0.1 mmol·L -1,PMS浓度1 mmol·L -1,可以在30 min内完全降解AO7.研究了催化剂含量、pH、共存阴离子等对AO7降解效果的影响.通过自由基消除实验,探索了0.10CTAB-BMO/光/PMS体系中存在的活性物种(h +、·O 2-、 1O 2、·OH和SO 4... 相似文献
10.
本文以盐酸林可霉素(LCM)为研究对象,探究其在UV/H 2O 2降解作用下的降解情况,探讨了H 2O 2浓度、初始pH值和有机物等影响因素对LCM的影响及机制.实验结果表明,当H 2O 2浓度为50 mg·L -1,pH=7.3,LCM浓度为10 mg·L -1,反应30 min后,LCM去除率达到98%,且反应过程遵循准一级动力学.利用高效液相色谱串联飞行时间质谱仪(LCMS-TOF 5600+)鉴别出其在UV/H 2O 2降解过程中主要产物的分子结构式,进而推导出可能的降解路径.利用TEST对降解过程中的产物进行毒性预测,结果表明,中间产物的毒性高于母体,对水质安全保障造成潜在风险. 相似文献
11.
Fe2O3-CeO2-Bi2O3/γ-Al2O3, an environmental friendly material, was investigated. The catalyst exhibited good catalytic performance in the CWAO of cationic red GTL. The apparent activation energy for the reaction was 79 kJ·mol−1. HO2· and O2·− appeared as the main reactive species in the reaction. ![]() The Fe 2O 3-CeO 2-Bi 2O 3/γ-Al 2O 3 catalyst, a novel environmental-friendly material, was used to investigate the catalytic wet air oxidation (CWAO) of cationic red GTL under mild operating conditions in a batch reactor. The catalyst was prepared by wet impregnation, and characterized by special surface area (BET measurement), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The Fe 2O 3-CeO 2-Bi 2O 3/γ-Al 2O 3 catalyst exhibited good catalytic activity and stability in the CWAO under atmosphere pressure. The effect of the reaction conditions (catalyst loading, degradation temperature, solution concentration and initial solution pH value) was studied. The result showed that the decolorization efficiency of cationic red GTL was improved with increasing the initial solution pH value and the degradation temperature. The apparent activation energy for the reaction was 79 kJ·mol −1. Hydroperoxy radicals (HO 2·) and superoxide radicals (O 2−·) appeared as the main reactive species upon the CWAO of cationic red GTL. 相似文献
12.
• Strong metal-support interaction exists on Pt/Fe3O4 catalysts. • Pt metal particles facilitate the formation of oxygen vacancies on Fe3O4. • Fe3O4 supports enhance the strength of CO adsorption on Pt metal particles. ![]() The self-inhibition behavior due to CO poisoning on Pt metal particles strongly impairs the performance of CO oxidation. It is an effective method to use reducible metal oxides for supporting Pt metal particles to avoid self-inhibition and to improve catalytic performance. In this work, we used in situ reductions of chloroplatinic acid on commercial Fe 3O 4 powder to prepare heterogeneous-structured Pt/Fe 3O 4 catalysts in the solution of ethylene glycol. The heterogeneous Pt/Fe 3O 4 catalysts achieved a better catalytic performance of CO oxidation compared with the Fe 3O 4 powder. The temperatures of 50% and 90% CO conversion were achieved above 260°C and 290°C at Pt/Fe 3O 4, respectively. However, they are accomplished on Fe 3O 4 at temperatures higher than 310°C. XRD, XPS, and H 2-TPR results confirmed that the metallic Pt atoms have a strong synergistic interaction with the Fe 3O 4 supports. TGA results and transient DRIFTS results proved that the Pt metal particles facilitate the release of lattice oxygen and the formation of oxygen vacancies on Fe 3O 4. The combined results of O 2-TPD and DRIFTS indicated that the activation step of oxygen molecules at surface oxygen vacancies could potentially be the rate-determining step of the catalytic CO oxidation at Pt/Fe 3O 4 catalysts. The reaction pathway involves a Pt-assisted Mars-van Krevelen (MvK) mechanism. 相似文献
13.
• Bi2O3 cannot directly activate PMS. • Bi2O3 loading increased the specific surface area and conductivity of CoOOH. • Larger specific surface area provided more active sites for PMS activation. • Faster electron transfer rate promoted the generation of reactive oxygen species. • 1O2 was identified as dominant ROS in the CoOOH@Bi2O3/PMS system. ![]() Cobalt oxyhydroxide (CoOOH) has been turned out to be a high-efficiency catalyst for peroxymonosulfate (PMS) activation. In this study, CoOOH was loaded on bismuth oxide (Bi 2O 3) using a facile chemical precipitation process to improve its catalytic activity and stability. The result showed that the catalytic performance on the 2,4-dichlorophenol (2,4-DCP) degradation was significantly enhanced with only 11 wt% Bi 2O 3 loading. The degradation rate in the CoOOH@Bi 2O 3/PMS system (0.2011 min −1) was nearly 6.0 times higher than that in the CoOOH/PMS system (0.0337 min −1). Furthermore, CoOOH@Bi 2O 3 displayed better stability with less Co ions leaching (16.4% lower than CoOOH) in the PMS system. These phenomena were attributed to the Bi 2O 3 loading which significantly increased the conductivity and specific surface area of the CoOOH@Bi 2O 3 composite. Faster electron transfer facilitated the redox reaction of Co (III) / Co (II) and thus was more favorable for reactive oxygen species (ROS) generation. Meanwhile, larger specific surface area furnished more active sites for PMS activation. More importantly, there were both non-radical ( 1O 2) and radicals (SO 4−•, O 2−•, and OH•) in the CoOOH@Bi 2O 3/PMS system and 1O 2 was the dominant one. In general, this study provided a simple and practical strategy to enhance the catalytic activity and stability of cobalt oxyhydroxide in the PMS system. 相似文献
14.
• Size and shape-dependent MnFe2O4 NPs were prepared via a facile method. • Ligand-exchange chemistry was used to prepare the hydrophilic MnFe2O4 NPs. • The catalytic properties of MnFe2O4 NPs toward dye degradation were fully studied. • The catalytic activities of MnFe2O4 NPs followed Michaelis–Menten behavior. • All the MnFe2O4 NPs exhibit selective degradation to different dyes. The magnetic nanoparticles that are easy to recycle have tremendous potential as a suitable catalyst for environmental toxic dye pollutant degradation. Rationally engineering shapes and tailoring the size of nanocatalysts are regarded as an effective manner for enhancing performances. Herein, we successfully synthesized three kinds of MnFe 2O 4 NPs with distinctive sizes and shapes as catalysts for reductive degradation of methylene blue, rhodamine 6G, rhodamine B, and methylene orange. It was found that the catalytic activities were dependent on the size and shape of the MnFe 2O 4 NPs and highly related to the surface-to-volume ratio and atom arrangements. Besides, all these nanocatalysts exhibit selectivity to different organic dyes, which is beneficial for their practical application in dye pollutant treatment. Furthermore, the MnFe 2O 4 NPs could be readily recovered by a magnet and reused more than ten times without appreciable loss of activity. The size and shape effects of MnFe 2O 4 nanoparticles demonstrated in this work not only accelerate further understanding the nature of nanocatalysts but also contribute to the precise design of nanoparticles catalyst for pollutant degradation. 相似文献
15.
In this paper, factors influencing the mineralization of dimethyl phthalate (DMP) during catalytic ozonation with a cerium-doped Ru/Al 2O 3 catalyst were studied. The catalytic contribution was calculated through the results of a comparison experiment. It showed that doping cerium significantly enhanced catalytic activity. The total organic carbon (TOC) removal over the doped catalyst at 100 min reached 75.1%, 61.3% using Ru/Al 2O 3 catalyst and only 14.0% using ozone alone. Catalytic activity reached the maximum when 0.2% of ruthenium and 1.0% of cerium were simultaneously loaded onto Al 2O 3 support. Results of experiments on oxidation by ozone alone, adsorption of the catalyst, Ce ion’s and heterogeneous catalytic ozonation confirmed that the contribution of heterogeneous catalytic ozonation was about 50%, which showed the obvious effect of Ru–Ce/Al 2O 3 on catalytic activity. 相似文献
16.
• A V2O5/TiO2 granular catalyst for simultaneous removal of NO and chlorobenzene. • Catalyst synthesized by vanadyl acetylacetonate showed good activity and stability. • The kinetic model was established and the synergetic activity was predicted. • Both chlorobenzene oxidation and SCR of NO follow pseudo-first-order kinetics. • The work is of much value to design of multi-pollutants emission control system. ![]() The synergetic abatement of multi-pollutants is one of the development trends of flue gas pollution control technology, which is still in the initial stage and facing many challenges. We developed a V 2O 5/TiO 2 granular catalyst and established the kinetic model for the simultaneous removal of NO and chlorobenzene (i.e., an important precursor of dioxins). The granular catalyst synthesized using vanadyl acetylacetonate precursor showed good synergistic catalytic performance and stability. Although the SCR reaction of NO and the oxidation reaction of chlorobenzene mutually inhibited, the reaction order of each reaction was not considerably affected, and the pseudo-first-order reaction kinetics was still followed. The performance prediction of this work is of much value to the understanding and reasonable design of a catalytic system for multi-pollutants (i.e., NO and dioxins) emission control. 相似文献
17.
• BiVO4/Fe3O4/rGO has excellent photocatalytic activity under solar light radiation. • It can be easily separated and collected from water in an external magnetic field. • BiVO4/Fe3O4/0.5% rGO exhibited the highest RhB removal efficiency of over 99%. • Hole (h+) and superoxide radical (O2•−) dominate RhB photo-decomposition process. • The reusability of this composite was confirmed by five successive recycling runs. Fabrication of easily recyclable photocatalyst with excellent photocatalytic activity for degradation of organic pollutants in wastewater is highly desirable for practical application. In this study, a novel ternary magnetic photocatalyst BiVO 4/Fe 3O 4/reduced graphene oxide (BiVO 4/Fe 3O 4/rGO) was synthesized via a facile hydrothermal strategy. The BiVO 4/Fe 3O 4 with 0.5 wt% of rGO (BiVO 4/Fe 3O 4/0.5% rGO) exhibited superior activity, degrading greater than 99% Rhodamine B (RhB) after 120 min solar light radiation. The surface morphology and chemical composition of BiVO 4/Fe 3O 4/rGO were studied by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The free radicals scavenging experiments demonstrated that hole (h +) and superoxide radical (O 2•−) were the dominant species for RhB degradation over BiVO 4/Fe 3O 4/rGO under solar light. The reusability of this composite catalyst was also investigated after five successive runs under an external magnetic field. The BiVO 4/Fe 3O 4/rGO composite was easily separated, and the recycled catalyst retained high photocatalytic activity. This study demonstrates that catalyst BiVO 4/Fe 3O 4/rGO possessed high dye removal efficiency in water treatment with excellent recyclability from water after use. The current study provides a possibility for more practical and sustainable photocatalytic process. 相似文献
18.
● Microwave-assisted catalytic NH3-SCR reaction over spinel oxides is carried out. ● SCR reaction temperature is tremendously lowered in microwave field. ● NO conversion of NiMn2O4 is highly up to 90.6% at 70°C under microwave heating. Microwave-assisted selective catalytic reduction of nitrogen oxides (NO x) was investigated over Ni-based metal oxides. The NiMn 2O 4 and NiCo 2O 4 catalysts were synthesized by the co-precipitation method and their activities were evaluated as potential candidate catalysts for low-temperature NH 3-SCR in a microwave field. The physicochemical properties and structures of the catalysts were characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), N 2-physisorption, NO adsorption-desorption in the microwave field, H 2-temperature programmed reduction (H 2-TPR) and NH 3-temperature programmed desorption (NH 3-TPD). The results verified that microwave radiation reduced the reaction temperature required for NH 3-SCR compared to conventional heating, which needed less energy. For the NiMn 2O 4 catalyst, the catalytic efficiency exceeded 90% at 70 °C and reached 96.8% at 110 °C in the microwave field. Meanwhile, the NiMn 2O 4 also exhibited excellent low-temperature NH 3-SCR reaction performance under conventional heating conditions, which is due to the high BET specific surface area, more suitable redox property, good NO adsorption-desorption in the microwave field and rich acidic sites. 相似文献
19.
This research investigates the performances of RuO 2/ZrO 2-CeO 2 in catalytic ozonation for water treatment. The results show that RuO 2/ZrO 2-CeO 2 was active for the catalytic ozonation of oxalic acid and possessed higher stability than RuO 2/Al 2O 3 and Ru/AC. In the catalytic ozonation of dimethyl phthalate (DMP), RuO 2/ZrO 2-CeO 2 did not enhance the DMP degradation rate but significantly improved the total organic carbon (TOC) removal rate. The TOC removal in catalytic ozonation was 56% more than that in noncatalytic ozonation. However this does not mean the catalyst was very active because the contribution of catalysis to the overall TOC removal was only 30%. The adsorption of the intermediates on RuO 2/ZrO 2-CeO 2 played an important role on the overall TOC removal while the adsorption of DMP on it was negligible. This adsorption difference was due to their different ozonation rates. In the catalytic ozonation of disinfection byproduct precursors with RuO 2/ZrO 2-CeO 2, the reductions of the haloacetic acid and trihalomethane formation potentials (HAAFPs and THMFPs) for the natural water samples were 38%–57% and 50%–64%, respectively. The catalyst significantly promoted the reduction of HAAFPs but insignificantly improved the reduction of THMFPs as ozone reacts fast with the THMs precursors. These results illustrate the good promise of RuO 2/ZrO 2-CeO 2 in catalytic ozonation for water treatment. 相似文献
20.
• CeO2 doping significantly improved low-temperature NH3-SCR activity on FeTiOx. • The crystallinity of FeTiOx was decreased dramatically after CeO2 doping. • Unique Ce-O-Fe structure in FeCe0.2TiOx accounted for its superior redox property. • Facile activation of NH3 to-NH2 on FeCe0.2TiOx promoted the DeNOx efficiency. FeTiO x has been recognized as an environmental-friendly and cost-effective catalyst for selective catalytic reduction (SCR) of NO x with NH 3. Aimed at further improving the low-temperature DeNO x efficiency of FeTiO x catalyst, a simple strategy of CeO 2 doping was proposed. The low-temperature (<250℃) NH 3-SCR activity of FeTiO x catalyst could be dramatically enhanced by CeO 2 doping, and the optimal composition of the catalyst was confirmed as FeCe 0.2TiO x, which performed a NO x conversion of 90% at ca. 200℃. According to X-ray diffraction (XRD), Raman spectra and X-ray absorption fine structure spectroscopy (XAFS) analysis, FeCe 0.2TiO x showed low crystallinity, with Fe and Ce species well mixed with each other. Based on the fitting results of extended X-ray absorption fine structure (EXAFS), a unique Ce-O-Fe structure was formed in FeCe 0.2TiO x catalyst. The well improved specific surface area and the newly formed Ce-O-Fe structure dramatically contributed to the improvement of the redox property of FeCe 0.2TiO x catalyst, which was well confirmed by H 2-temperature-programmed reduction (H 2-TPR) and in situ XAFS experiments. Such enhanced redox capability could benefit the activation of NO and NH 3 at low temperatures for NO x removal. The detailed reaction mechanism study further suggested that the facile oxidative dehydrogenation of NH 3 to highly reactive-NH 2 played a key role in enhancing the low-temperature NH 3-SCR performance of FeCe 0.2TiO x catalyst. 相似文献
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