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1.
纳米Pd/C催化剂的制备及其催化氧化乙二醛生成乙醛酸的研究 总被引:1,自引:0,他引:1
利用化学还原法分别以PdCl2和Pd(OAc)2为前体制备了胶体Pd纳米粒子,然后采用胶体负载法获得2种Pd/C催化剂并应用于催化乙二醛氧化生成乙醛酸的反应。研究了催化反应条件如温度、乙二醛初始浓度以及在催化剂制备中Pd负载量、使用的前体对催化反应的影响,从而在最佳催化条件下得到乙醛酸产率为31.07%,选择性为67.06%的反应结果;利用XPS技术对Pd/C催化剂使用前后Pd的表面化学状态进行了表征,简要探讨了Pd/C催化剂的选择性和催化剂失活机理。 相似文献
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制备氧化镨纳米棒,利用浸渍法在纳米棒上负载金属银,得到稳定性较强的复合纳米材料。对合成的纳米样品进行XRD、TEM及HRTEM等表征。并以Pr6O11/Ag复合纳米材料催化烯烃环氧化反应,试验表明环己烯环氧化反应催化效果较好。 相似文献
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采用水热晶化法一步制备了铈锆摩尔比不同的PtCe_xZr_(1-x)O_2系列催化剂,测定其比表面积、储氧量、氢气还原温度等物化性能参数,并进行结构表征,研究催化剂组成中铈锆摩尔比(n_(Ce)/n_(Zr))对催化剂结构和性能的影响。结果表明,当n_(Ce)/n_(Zr)=5:5时,制备得到的PtCe_(0.5)Zr_(0.5)O_2催化剂晶粒尺寸最小,储氧量较高,氢气还原温度低,微观结构为四方相和立方相2种晶型结构并存的固溶体。与传统贵金属浸渍负载方法制备的Pt/Ce_(0.5)Zr_(0.5)O_2催化剂相比较,水热晶化法一步制备的PtCe_(0.5)Zr_(0.5)O_2催化剂对碳烟的低温氧化具有更优的催化活性。 相似文献
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以RuO2和CuO为活性组分和辅助活性组分,添加CeO2作为助剂,采用硝酸盐浸渍法负载在分子筛载体上,焙烧制备Ru-Cu-Ce复合催化剂。采用比表面分析仪(BET)、X射线衍射(XRD)和透射电子显微镜(TEM)等对催化剂进行表征,用静态实验评价氧化去除氨氮的催化性能。结果表明,Cu和Ce的添加能够提高Ru催化剂的性能,Ce可以抑制Cu的溶出损失。催化剂制备的最佳焙烧条件为300℃焙烧4.5 h。对200 mL初始浓度为205.8 mg/L的模拟氨氮废水,0.25%Ru-1%Cu- 1%Ce催化剂常压氧化降解的最佳条件为:初始pH=10,温度80℃,30%双氧水添加量为处理水量的1/2000,氨氮去除率可达85.6%,催化剂重复使用7次性能无明显降低。 相似文献
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采用浸渍法制备了2个系列的Ru/Mn-Ce/TiO2及Ru/TiO2催化剂,并用XRD、TEM、BET等方法对催化剂进行表征。在T=270℃和Po2=1.5MPa条件下,在间歇式反应釜中对丁二酸进行降解实验。结果表明60min内丁二酸降解的总有机碳(TOC)去除率为80%~99.8%;在钌含量相同的情况下,Ru/Mn-Ce/TiO2催化剂的催化活性高于Ru/TiO2催化剂;Ru含量较低的情况下,Mn、Ce对提高催化活性有很大作用,但Ru含量增加时Mn、Ce的作用减弱;氢还原的温度对Ru/TiO2系列催化剂的催化氧化活性有明显影响,500℃还原钌所得催化剂对丁二酸的催化氧化活性优于350℃。 相似文献
6.
采用浸渍法制备改性活性炭负载金催化剂(Au/AC),并通过N2吸附-脱附、光电子能谱(XPS)对该催化剂进行表征,考察Au/AC催化剂在室温下对低浓度臭氧、甲苯以及二者共存时的催化分解性能.结果表明:Au/AC催化剂对臭氧具有优良的催化分解活性,在室温、空速76 000 h-1、相对湿度(45±5)%条件下,Au/AC对初始浓度为(55±5) mg/m3 的臭氧在2 300 min时的去除率为91.3%;Au/AC对甲苯的去除未表现出明显的催化分解性能,而是以吸附作用为主;在臭氧和甲苯共存的条件下,Au/AC对臭氧的催化分解活性显著降低;与臭氧反应后,Au/AC的表面石墨碳含量显著降低,说明臭氧能够通过Au/AC催化其与活性炭的反应得以降解,且在反应前后,活性组分Au能够保持稳定的单质价态. 相似文献
7.
Pt/C催化剂的制备及其催化氧化乙二醛反应的研究 总被引:1,自引:0,他引:1
以H2PtCl6为前驱体、采用化学还原法制备Pt胶体,然后将其负载于不同种类的活性炭上制备了1.0% Pt/C催化剂并应用于催化氧化乙二醛生成乙醛酸的反应.研究了活性炭的种类对催化活性的影响;比较了各种1.0% Pt/C催化剂催化乙二醛反应的结果.根据对产物溶液中的各组分的分析,结果表明以聚乙二醇(PEG)为保护剂、硼氢化钠作还原剂所制备的Pt胶体溶液负载在未处理过的国产活性炭(YHB)上获得的催化剂具有良好的催化活性和选择性.在最佳催化剂制备条件下,催化反应达60 min时,乙醛酸的产率即达到了66.88%,选择性为71.77%. 相似文献
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以碳纳米管(CNTs)为载体,采用化学沉积法制备了纳米Ni/CNTs、Cu/CNTs复合粒子,利用TEM、SEM、XRD、EDS、BET、XPS等方法对产物的形貌、结构、元素含量进行了表征,并应用DSC研究了纳米Ni、Cu、CNTs等单一纳米粒子及Ni/CNTs、Cu/CNTs复合粒子对AP热分解的催化作用.结果表明:Ni/CNTs、Cu/CNTs复合粒子结晶好、包复均匀、比表面积大.纳米Ni、Cu等单一纳米粒子和Ni/CNTs、Cu/CNTs复合粒子均能使AP热分解的高温分解峰峰温降低、表观分解热增加,具有良好的催化性能.相比较而言,纳米复合粒子的催化性能均优于其相应单一组分,表现出良好的正协同作用.复合粒子中以Cu/CNTs复合粒子的催化效果最为显著,使AP的高温分解峰峰温降低112.15℃,使总表观分解热增加839 J/g.并初步探讨了催化机制. 相似文献
11.
Catalysts for low temperature CO oxidation were prepared by decorating hydroxyapatite (HAp) ceramic foam scaffolds with highly
dispersed gold nanocrystals using a deposition-precipitation (DP) process. Catalytic activity, microstructure and crystallinity
were studied as a function of reagent pH (4–12) and aging time (10, 30, 60 min) for powders and porous supports. Superior
products with small (≤ 5 nm) gold crystals distributed homogeneously over HAp foam were obtained at pH 8–9. Larger crystal
sizes and colloidal gold agglomeration appeared at longer aging times. The optimized catalyst prepared by reaction at pH 9
for 30 min showed 100% CO conversion to CO2 at 150°C. The Au-HAp composite demonstrated excellent durability by retaining structural and crystallographic integrity with
no loss of activity when tested at 65°C out to 166 h. 相似文献
12.
Xin Guo Xue-Quan Sun Yun Guo Yang-Long Guo Yun-Song Wang Li Wang Wang-Cheng Zhan 《稀有金属(英文版)》2021,(5):1056-1066
Au-Cu bimetallic nanoparticles with uniform size,shape,and compositions were synthesized by wet chemistry method,and then the Au-Cu/SiO_2 catalyst supported on SiO_2 was prepared.Meanwhile,their catalytic activity for the selective oxidation of propene to acrolein using O_2 as an oxidant was evaluated.The bimetallic catalyst shows a significantly enhanced catalytic performance comparing with Au and Cu monometallic catalysts.Characterization of the materials and kinetic study was conducted to explore the cooperating mechanism of Au and Cu for improving the catalytic activity of the bimetallic catalyst.Cu component can segregate to the alloy surface and the Au-Cu alloy transferred to Au-CuO core/shell structure after annealing during the preparation process.Based on the Mars-van Krevelen mechanism for the selective oxidation of propene over the prepared catalysts,the coexistence of CuO can promote the adsorption and activation of O_2.Meanwhile,the electrons transfer from Au to Cu in the catalyst can facilitate the adsorptions of both oxygen on CuO sites and propene on Au sites.The combined effects of the above two aspects result in the high catalytic activity of the Au-Cu/SiO_2 catalyst for selective oxidation of propene to acrolein,compared to the Au/SiO_2 and CuO/SiO_2 catalysts. 相似文献
13.
王乾 《中国有色金属学会会刊》2007,17(A02):622-625
The nano-composite powders of CeO2/Zn were prepared with high energy ball milling and the nano-composite materials of CeO2/Zn were fabricated with vacuum sintering powder metallurgy. Meanwhile, the composite and structure were analyzed by the means of XRD and FESEM. From the comparison of different nano-CeO2 contents composites, the best corrosion resistance and hardness, and the optimum content of nano-CeO2 were achieved. The result shows that corrosion resistance, hardness and uniformity of metal structure can be improved significantly with nano-CeO2; at the same time, the optimal corrosion resistance, hardness and microstructure are obtained when the mass fraction of nano-CeO2 is 1%. 相似文献
14.
以钛酸丁酯为先驱体、无水乙醇为溶剂、二乙醇胺为鳌合剂,采用溶胶-凝胶浸渍提升法制备钛基TiO2-SnO2复合电极.借助于含油废水化学需氧量(COD)的去除效果和紫外吸收光谱考察了电极的电催化氧化能力.并采用SEM、XRD和EDX等表征方法分析了Sn的掺杂对所制备电极表面形貌、涂层晶体结构和电极表层的元素组成的影响,通过电化学线性伏安扫描测定了其析氧电位,分析了电极结构与电催化特性之间的关系.结果表明,当热处理温度为500℃时,所制备电极的涂层中TiO2主要为锐钛矿型,掺杂适量Sn后,电极的表面变得更加平滑、致密,涂层表面晶粒明显细化.当Sn的摩尔掺杂比为n(Ti):n(Sn)=100:10时,复合氧化物涂层电极的电催化性能最好,电极的析氧电位为2.1 V,此电极处理含油废水60 min时,COD去除率达到了87.5%,较未添加Sn的电极相比对COD的去除率提高了26.7%,这说明掺杂适量的Sn提高了电极的催化性能. 相似文献
15.
Yan WANG Ze-hua CHEN Jing HUANG Gao-jie LI Jian-liang CAO Bo ZHANG Xing-ying CHEN Huo-li ZHANG Lei JIA 《中国有色金属学会会刊》2018,28(11):2265-2273
The reduced graphene oxide (rGO) supported cobalt oxide nanocatalysts were prepared by the conventional precipitation and hydrothermal method. The as-prepared rGO-Co3O4 was characterized by the XRD, Raman spectrum, SEM, TEM, N2-sorption, UV-Vis, XPS and H2-TPR measurements. The results show that the spinel cobalt oxide nanoparticles are highly fragmented on the rGO support and possess uniform particle size, and the as-prepared catalysts possess high specific surface area and narrow pore size distribution. The catalytic properties of the as-prepared rGO-Co3O4 catalysts for CO oxidation were evaluated through a continuous-flow fixed-bed microreactor-gas chromatograph system. The catalyst with 30% (mass fraction) reduced graphene oxide exhibits the highest activity for CO complete oxidation at 100 °C. 相似文献
16.
《Synthetic Metals》2007,157(18-20):751-757
Polyaniline–Fe2O3 composites were chemically prepared by oxidative polymerization of aniline in phosphoric acid medium with ammonium persulphate as oxidant. Different ratios of aniline–Fe2O3 were taken to prepare polyaniline–Fe2O3 composites, i.e. 1:2, 1:1, 2:1. The composites were characterized by FTIR, XRD and SEM. Using the prepared composites, primer paints with acrylic binder were prepared and coated on the steel samples. The corrosion protection ability of the coating was found out by EIS method in 3% NaCl solution. It has been found that the coating with composite of 1:1 ratio of aniline:Fe2O3 is found to offer higher protection than the coating with other ratios and plain Fe2O3. 相似文献
17.
纳米CeO2p/Zn-4.5%Al复合材料的高能超声制备及其力学性能 总被引:1,自引:1,他引:1
设计一套高能超声搅拌装置,并在氩气氛保护下,通过对纳米CeO2进行预处理及控制工艺参数,用该装置制备了CeO2质量分数分别为1%~6%的纳米CeO2p/Zn-4.5%Al复合材料。用SEM观察颗粒的分散情况,测试材料的室温拉伸性能。结果表明:所设计的装置结构合理、超声作用效果佳;纳米CeO2可以单粒分散入基体合金中;随着CeO2质量分数的增加,复合材料的抗拉强度和弹性模量明显高于基体合金,伸长率则降低;复合材料的断裂机制为脆性断裂。 相似文献
18.
Iron oxide and metal doped iron oxide nanocomposites have found attractive and versatile applications in many research areas such as catalysts, sensors, and biomedicine. This work reports a surfactant-free hydrolysis approach for the synthesis of hematite (α-Fe2O3) and Pd doped α-Fe2O3 nanoparticles with low-temperature catalytic activity. By this method, iron oxide rod-like nanoparticles were achieved by hydrolysis of ferric chloride salt with dilute HCl at a temperature of 100 °C. The Pd/iron oxide nanocomposites were obtained by adding citric acid into a mixture of iron oxide nanoparticles and palladium precursor (Pd(CH3CN)2Cl2) under a reflux heating at 90 °C for 2 h. This method is featured as no use of any surfactants and templates, and no requirement of high-temperature thermal decomposition that are usually required for shape/size control in polar or nonpolar solvents. More importantly, it was found that the Pd/α-Fe2O3 nanocomposites exhibited high low-temperature catalytic activity in carbon monoxide (CO) oxidation. 相似文献
19.
Nano-scale platinum catalysts were prepared on a glass carbon electrode by cyclic voltammetry. The surface morphology and active area of the catalysts, and their catalytic activity toward methanol oxidation and oxygen reduction were studied by SEM, linear and cyclic voltammetry. The result shows that the diameters of global Pt particles are affected by the scan rate of cyclic voltammetry: the faster the scan rate is, the smaller the diameters of Pt particles are. The size of the nano-scale platinum catalysts has different effects on their catalytic activity toward oxygen reduction and methanol oxidation: the catalyst with a size of 100 nm shows its best activity toward methanol oxidation, but the catalyst with a size of 65 nm shows its best activity toward oxygen reduction. 相似文献
20.
利用5 kW CO2激光器,在Q235低碳钢表面熔覆微米或纳米CeO2/Ni基合金复合材料,制备了涂层.利用光学显微镜、扫描电镜和X射线衍射仪分析比较了熔覆层的组织、磨损彤貌及相结构,利用MM-200环-块式滑动磨损机检测了熔覆层的耐磨性.结果表明:熔覆层的主要相为γ-Ni和Cr23C6以及CeNi5,Ni3Si和Ni3B等;加入微米Ce02的Ni基激光熔覆层组织明显细化,并有大量的放射状等轴晶;加入纳米CeO2的Ni基激光熔覆层出现大量更加细小的等轴晶,并且组织致密.含纳米CeO2的Ni基熔覆层与纯Ni基的相比,耐磨性大幅度提高,磨损机理由黏着磨损转变为微动磨损. 相似文献