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借助水热法,以正硅酸乙酯为硅源,十六烷基三甲基溴化铵为模板剂,在碱性条件下制备了纳米MCM-41分子筛。通过固相热扩散法将La2O3组装到MCM-41介孔孔道中,制备出含La2O3不同浓度的(MCM-41)-La2O3主-客体纳米复合材料。采用化学分析、粉末XRD、FTIR、77K低温N2吸附-解吸附、固体扩散漫反射吸收光谱、拉曼光谱、扫描电镜和发光光谱对主-客体复合材料进行表征。粉末XRD结果表明,La2O3组装到MCM-41分子筛的孔道后并未破坏分子筛骨架,在所制备的(MCM-41)-La2O3主-客体纳米复合材料中MCM-41骨架结构仍然具有较高的有序性,并且,随着植入客体材料浓度的增加复合材料的有序度有所降低。红外光谱表明所制备的纳米复合材料主体分子筛骨架完好;低温氮气吸附-解吸附技术表明La2O3已经部分地占据了MCM-41分子筛孔道,导致分子筛的比表面积和孔体积都有所降低;固体扩散漫反射吸收光谱表明吸收光谱的吸收峰发生了蓝移现象,并表现出量子限域效应,说明La2O3已经组装到了MCM-41分子筛的孔道中;拉曼光谱表明所制备的复合材料没有出现新的特征峰,表明La2O3已经组装到了MCM-41分子筛的孔道中;扫描电镜表明(MCM-41)-La2O3样品的外观非常规整,主要呈现的是球状结构,La2O3含量为10%时,(MCM-41)-La2O3的平均粒径为(114±10)nm。发光光谱研究结果表明,所制备的复合材料(MCM-41)-La2O3样品在396nm处具有较好的发光性质,因而具有作为发光材料潜在应用前景。 相似文献
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用原位合成法,以酸性Al2O3为载体,酞菁类金属大环配合物为活性组分,合成出CoPc/Al2O3新型环氧化催化剂,红外、紫外-可见、热重分析及XPS证实能够利用该法在Al2O3上固载CoPc催化剂,且催化剂稳定性增加,不易流失.以分子氧为氧源,异丁醛为共还原剂考察CoPc/Al2O3催化剂对环己烯的催化环氧化活性及催化剂的重复使用情况.结果表明,与均相催化剂相比,固载后环己烯转化率增加了8%,环氧环己烷选择性增加了23%,催化剂重复使用4次后,活性仅降低4%. 相似文献
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Cu/ZnO-TiO2复合半导体光催化材料的制备与表征 总被引:6,自引:0,他引:6
The metallic Cu modified n-p coupled semiconductors Cu/ZnO-TiO2 were prepared by sol-gel method, and their crystal structure, surface composition and absorptivity of UV light were investigated by techniques of DTA-TG, XRD, TEM, BET, TPR, IR and UV-Vis. The results show that the main crystal structure of the coupled-semiconductors is anatase TiO2 with the particle size in the range of 10~16 nm and BET surface area above 80 m2·g-1. In the process of Sol-gel the probability to form ZnO is reduced because of the dilution of Zn2+ with Ti(OC4H9)4. But through the molecular-level contact with TiO2, Zn2+ cations take the places of the O-tetrahedral and O-octahedral centers to partly form Zn2TiO4, and the coupling effects decrease the reflectivity of semiconductors in the wavelength region of 250~400 nm. A photo-exciting mechanism of the semiconductors embedded with metallic Cu was proposed. The Fermi energy of metallic Cu is in the band gap of ZnO and TiO2, so the addition of metallic Cu offers new energy bands to give and receive the photoelectrons, thus expanding the absorption region of the semiconductors to visible light. 相似文献
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高比表面CexZr1-xO2复合氧化物的制备及表征 总被引:2,自引:0,他引:2
分别采用共沉淀法和阴离子表面活性剂模板法制备了CexZr1-xO2复合氧化物。采用XRD、AFM、FTIR以及N2吸附-脱附等方法对样品进行了表征。结果表明,共沉淀法合成的样品在500 ℃煅烧2 h后,生成了立方相Ce0.75Zr0.25O2和四方相Ce0.5Zr0.5O2固溶体,比表面积为62.1 m2·g-1,孔体积为0.097 cm3·g-1;以阴离子表面活性剂十二烷基苯磺酸钠(SDBS)为模板剂,乙二胺为助模板剂合成的样品在500 ℃煅烧2 h后,生成了纯四方相Ce0.5Zr0.5O2固溶体,比表面积为180 m2·g-1,孔体积为0.182 cm3·g-1。结果表明,以阴离子表面活性剂SDBS为模板剂,可以合成高比表面积且具有介孔结构的Ce0.5Zr0.5O2复合氧化物;加入乙二胺作为助模板剂可明显的提高比表面积和孔体积。 相似文献
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Customizing core-shell nanostructures is considered to be an efficient approach to improve the catalytic activity of metal nanoparticles. Various physiochemical and green methods have been developed for the synthesis of core-shell structures. In this study, a novel liquid-phase hydrogen reduction method was employed to form core-shell Pt@Au nanoparticles with intimate contact between the Pt and Au particles, without the use of any protective or structure-directing agents. The Pt@Au core-shell nanoparticles were prepared by depositing Au metal onto the Pt core; AuCl4− was reduced to Au(0) by H2 in the presence of Pt nanoparticles. The obtained Pt@Au core-shell structured nanoparticles were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution TEM, fast Fourier transform, powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and H2-temperature programmed reduction (H2-TPR) analyses. The EDX mapping results for the nanoparticles, as obtained from their scanning transmission electron microscopy images in the high-angle annular dark-field mode, revealed a Pt core with Au particles grown on its surface. Fourier transform measurements were carried out on the high-resolution structure to characterize the Pt@Au nanoparticles. The lattice plane at the center of the nanoparticles corresponded to Pt, while the edge of the particles corresponded to Au. With an increase in the Au content, the intensity of the peak corresponding to Pt in the FTIR spectrum decreased slowly, indicating that the Pt nanoparticles were surrounded by Au nanoparticles, and thus confirming the core-shell structure of the nanoparticles. The XRD results showed that the peak corresponding to Pt shifted gradually toward the Au peak with an increase in the Au content, indicating that the Au particles grew on the Pt seeds; this trend was consistent with the FTIR results. Hence, it can be stated that the Pt@Au core-shell structure was successfully prepared using the liquid-phase hydrogen reduction method. The catalytic activity of the nanoparticles for the oxidation of toluene was evaluated using a fixed-bed reactor under atmospheric pressure. The XPS and H2-TPR results showed that the Pt1@Au1/Al2O3 catalyst had the best toluene oxidation activity owing to its lowest reduction temperature, lowest Au 4d & 4f and Pt 4d & 4f binding energies, and highest Au0/Auδ+ and Pt0/Pt2+ proportions. The Pt1@Au2Al2O3 catalyst showed high stability under dry and humid conditions. The good catalytic performance and high selectivity of Pt@Au/Al2O3 for toluene oxidation could be attributed to the high concentration of adsorbed oxygen species, good low-temperature reducibility, and strong interaction. 相似文献
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CuO-MnO2/Al2O3 催化臭氧化催化剂的制备、结构表征及性能 总被引:1,自引:0,他引:1
采用浸渍法,以Al2O3为载体制备了氧化铜和二氧化锰复合的双组分负载型金属催化臭氧化催化剂.以松花江水的UV254去除率作为催化剂活性指标,通过正交试验,确定了催化剂的最佳制备条件.实验结果表明,催化剂的最佳制备条件如下:浸渍5h,活性组元体积比为3:1,于90℃干燥2h,于200℃焙烧3h.采用扫描电镜对催化剂的结构进行了表征;通过TG-DTA测试分析了催化剂热分解过程的反应速率、热效应和物质变化过程;运用XPS分析了催化剂表面元素的组成、元素相对含量和元素价态. 相似文献
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SO2-4/ZrO2/Fe3O4/Al2O3磁性固体超强酸的制备与表征 总被引:5,自引:0,他引:5
用化学共沉淀法制备了一系列SO2-4/ZrO2/Fe3O4/Al2O3磁性固体超强酸, 利用XRD、IR、TG-DSC、VSM、TEM及HRTEM等手段对样品结构进行了表征. 结果表明, 引入一定量的Fe3O4和Al2O3有利于四方晶相ZrO2(t)结构的稳定;Fe3O4超细粒子的引入, 使固体超强酸具备了超顺磁性;HRTEM 结果显示ZrO2晶体生长趋向于ZrO2(t)的[101]方向,其(101)晶面间距为d(101)=0.29 nm, 与XRD 衍射结果一致. Hammett 指示剂测得样品SZA-20-200-800酸强度(H0<-13.8)最强, 酸性大于浓硫酸(H0=-11.9). 相似文献
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以SBA-15为前驱体,在660 ℃下通过镁热还原反应得到介孔硅材料,并对其进行碳包覆处理,成功地制备了有序介孔Si/C(OMP-Si/C)复合材料。该OMP-Si/C材料保留了SBA-15模板的有序蜂窝孔道,并且形成具有高堆积密度的莲藕链束结构。文中还提出了一个SBA-15镁热还原液态环境反应模型,探讨了660 ℃下硅的高度有序介孔与莲藕链束结构的形成机理。利用X射线衍射(XRD)仪、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、氮气吸脱附法及拉曼光谱对样品物相和微观形貌进行了表征。这种高度有序介孔Si/C复合材料具有优异的电化学性能,展现出其在第二代锂电池负极材料领域中的潜在应用价值。 相似文献
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三维虫孔状介孔纳米粒子Ag2O/Ce0.6Zr0.35Y0.05O2的制备、表征及其对甲烷氧化反应的催化性能 总被引:1,自引:0,他引:1
以十六烷基三甲基溴化铵(CTAB)为模板剂, 采用改进的共沉淀法合成了高比表面积的虫孔状介孔Ce0.6Zr0.35Y0.05O2(CZY)立方晶相结构的纳米粒子, 用浸渍法制备了Ag2O质量分数为0.2%—4.0%的Ag2O/CZY催化剂, 以XRD, HRSEM, HRTEM/SAED, H2-TPR和XPS等表征手段测定了CZY 和Ag2O/CZY催化剂的物化性质, 考察了其对甲烷氧化反应的催化性能. 结果表明, 质量分数为2.0%的Ag2O/CZY催化剂在空速为50000 h-1、甲烷/氧气摩尔比为1:4和反应温度为600 ℃的条件下, 可使甲烷完全氧化成CO2和H2O, 且基本上消除了在升温、降温过程中甲烷转化率随温度变化的“滞后回线”现象. 可见, Ag2O/CZY的优良催化性能与CZY具有发达的三维虫孔状介孔结构、较大的比表面积、较强的储释氧能力及其稳定活性相Ag2O等因素有关. 相似文献
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New organic‐inorganic hybrid materials and their anti‐electrostatic hybrid membranes are prepared via sol‐gel process. The polycondensation of epoxy oligomers and AEAPS/Al2O3 complexes which are organically surface modified submicrometer aluminum trihydroxide inorganic fillers with an active aminoterminal silane coupling agent, N‐(2‐aminoethyl)‐3‐aminopropyltrimethoxysilane (AEAPS), are performed. AEAPS enhances the interfacial interactions between the inorganic fillers and epoxy polymers. Meanwhile, this coupling agent maintains well dispersion of fillers in these composites. To improve the mechanical strength and thermal stability, pyromellitic dianhydride (PMDA) is used as curing agent. These hybrid films prepared from this method have excellent physical properties, such as UV‐shielding, high transmission in visible resign (> 85%), high hardness (7~8H) , high adhesive force (7~8) and low relative surface resistance (9.71 × 1011~1.26 × 1010 Ω/cm2) with anti‐electrostatic characters. For thermal resistance, the best Td value of epoxy/PMDA/AEAPS/Al2O3 is 378.6 °C which is 85.4 °C higher than that of neat epoxy resin. Physical properties of these materials are almost the same as those of the nanocomposites prepared from expensive colloid Al2O3. Evidences from TEM micrograph show that the inorganic additives are dispersed evenly in organic matrix with nanometer scale. 相似文献
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利用共沉淀法制备了具有介孔结构的Ce0.5Zr0.5O2固溶体载体,然后浸渍不同质量分数(10%、20%、30%)的活性组分钴,制备了系列Co/Ce0.5Zr0.5O2催化剂。利用N2物理吸附(BET)、X射线粉末衍射(XRD)、H2-程序升温还原(H2-TPR)、扫描电子显微镜(SEM) 、透射电子显微镜(TEM) 、 程序升温氧化(TPO)和热重(TG)等手段对制备和反应后的催化剂进行了表征,研究了它们对甲烷部分氧化制合成气反应的催化性能。研究结果表明,铈锆固溶体负载的钴比较容易被还原,该系列催化剂具有较高的活性和对H2及CO的选择性,且随Co含量的增加,催化剂的活性和对H2和CO的选择性得到提高的同时,也增强了催化剂的抗积炭性能。 相似文献
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以镍钴氢氧化物为原料,采用异丙醇铝水解法合成Ni0.88Co0.07Al0.05(OH)2,将前驱体与锂源充分混合,通过3种烧结条件制备出球形LiNi0.88Co0.07Al0.05O2正极材料,借助X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)以及电化学测试等表征手段对材料的晶体结构、微观形貌和电化学性能进行了较系统的研究。研究表明,在500℃下保温3 h、700℃下保温14 h的条件下合成的LiNi0.88Co0.07Al0.05O2具有良好的综合电化学性能,0.2C放电比容量达192.2 mAh·g^-1,首次充放电效率为81.6%,1C放电比容量为190.7 mAh·g^-1,100周后放电比容量为141.1 mAh·g^-1,容量保持率达到73.4%。 相似文献