共查询到19条相似文献,搜索用时 140 毫秒
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用沉积-沉淀法制备了Au/La2O3/TiO2催化剂,考察了制备条件和反应条件对催化剂活性的影响,并利用X射线衍射(XRD)、透射电子显微镜(TEM)等测试手段对催化剂进行了表征. 结果表明La2O3的加入可使催化剂催化甲醇水重整的催化活性明显提高,且明显降低产物气体中CO和CH4的含量,使氢气选择性明显增加. 当nH2O/nCH3OH=1.0、液体进料空速WHSV=3.42 h-1、反应温度为275℃时,Au/La2O3/TiO2催化剂催化甲醇水蒸汽重整制氢反应的效果最佳. 相似文献
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以溶胶-凝胶法制备TiO2载体,用沉积-沉淀法制备出一系列负载型Au/TiO2。系统考察了焙烧温度、金的负载量、反应液pH值、沉淀剂种类以及Cl-存在与否等制备参数对催化剂活性的影响。以室温下CO的催化氧化为探针反应,确定催化剂的最适宜制备参数,并对优化的质量分数为1.0%的Au/TiO2催化剂进行了活性稳定性测试。结果表明:Au/TiO2的最适宜焙烧温度是200~350℃;反应液的最适宜pH值为9;最适宜沉淀剂是NaOH;金的负载量(质量分数,下同)在0.5%~5.0%范围内时,金含量越高,催化剂活性和热稳定性越好。大量Cl-的存在能导致催化剂活性的显著下降。对优化的Au/TiO2催化剂在室温下催化氧化不同浓度的CO进行循环测试,经历3次循环,连续反应2 160 min后,CO的转化率仍为100%。 相似文献
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通过并流共沉淀法制备了Au/-Fe2O3催化剂,考察了金负载量及焙烧温度对Au/-Fe2O3催化剂的物化结构及其选择性氧化富氢气体中CO催化性能的影响。研究结果表明,金负载量和焙烧温度对催化剂的性能均有较大影响,金负载量为1.5%(wt),低温焙烧(200~400℃)时制得的Au/-Fe2O3催化剂对CO选择性氧化反应具有很好的催化活性和选择性,其中金负载量为1.5%(wt)、300℃焙烧的Au/-Fe2O3催化剂,在40℃时对富氢气体中CO的转化率达到100%,选择性为 66%,该催化剂连续反应120h催化活性没有明显下降。XRD、BET和TEM分析结果表明,催化剂的性能与单质Au的粒径有关,粒径越小,催化活性越高。 相似文献
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以拟薄水铝石为原料,通过高温焙烧制备γ-Al2O3,并以γ-Al2O3为载体,通过吸附还原法制备了3Au/γ-Al2O3催化剂[其中3为m(Au)∶m(催化剂)=3%]。通过TEM、XRD、ICP-OES和BET对催化剂的形貌和结构进行了表征,考察了3Au/γ-Al2O3催化剂在1,2-丙二醇氧化酯化制备高附加值C3化学品的催化性能。结果表明,Au颗粒的高效分散有助于提高催化剂的性能;在优选条件下,以甲醇为溶剂,无碱助剂的体系中1,2-丙二醇的转化率为63.0%,C3化学品总选择性为63.6%;并且发现增加催化剂中Au负载量,可能会影响反应的发生,从而降低主产物的选择性。 相似文献
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采用碳源助剂改性载体TiO2,制备催化剂Ni-Mo/TiO2催化剂,考察载体焙烧温度对催化剂性能的影响,并采用透射电镜(TEM)、X射线能谱(EDS)、X射线衍射(XRD)和X射线光电子能谱(XPS)等对载体及催化剂进行表征.结果表明,焙烧温度为500~600℃时,TiO2晶粒大小适中,活性元素分布均匀,焙烧温度为550℃的载体制备的催化剂加氢性能较好. 相似文献
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以TiO2为载体,利用分步浸渍法制备了Pt-CeO2/TiO2、Pt-ZrO2/TiO2、Pt-La2O3/TiO2、Pt-Pr2O3/TiO2和Pt-SnO2/TiO2催化剂,并催化湿式氧化高浓度苯酚废水。Pt-CeO2/TiO2催化剂的活性最好,在反应温度为160℃、氧分压为2.25 MPa,反应时间为2 h的条件下,苯酚和COD的去除率分别为87.53%和72.06%。进一步研究助剂含量对催化剂性能的影响,当CeO2负载量为12.5%时,催化剂Pt-CeO2/TiO2的催化性能最佳。XRD和TEM结果表明,助剂CeO2的引入起到降低Pt的粒径,提高Pt在载体表面的分散度的作用。 相似文献
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Ni/SiO2催化剂的制备条件对催化间二硝基苯加氢反应性能的影响 总被引:9,自引:1,他引:8
将Ni/SiO2催化剂应用于间二硝基苯加氢反应中,考察了该催化剂制备过程中焙烧温度和还原温度对其催化性能的影响,并通过BET、XRD、TEM、TPR等方法对催化剂进行了表征.结果表明,在实验研究范围内,随着焙烧温度的提高,Ni/SiO2催化剂比表面积降低,NiO与载体SiO2之间的相互作用逐渐增强,催化剂的还原温度明显提高,活性组分Ni的晶粒度增大,焙烧温度为773 K时催化剂具有最佳的催化反应性能,此时活性组分Ni以高分散状态存在.催化剂的还原温度对Ni/SiO2催化剂的结构和催化性能影响显著,当还原温度较低时,活性组分还原不完全,催化剂活性较低;而还原温度太高会使活性组分烧结,导致催化剂活性明显降低;还原温度为723 K时催化剂表现出最佳的活性和选择性. 相似文献
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脱硝催化剂的开发利用是选择性催化还原(Selective catalytical reduction,SCR)脱硝技术的核心.载体对SCR脱硝催化剂性能影响很大,锐钛矿型TiO2载体因其优异的性能而成为应用研究的热点.本文主要阐述SCR脱硝催化剂载体的研究进展;重点论述TiO2载体粒径、比表面积对脱硝催化剂性能及其对焙烧制度、负载量等制备条件的影响;简述TiO2载体孔结构、形貌对催化脱硝性能的影响.最后,展望了利用TiO2载体制备低温高效SCR脱硝催化剂的前景. 相似文献
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Jia-Ying Xin Kai Lin Yan Wang Chun-Gu Xia 《International journal of molecular sciences》2014,15(12):21603-21620
Methanobactin (Mb) is a copper-binding peptide that appears to function as an agent for copper sequestration and uptake in methanotrophs. Mb can also bind and reduce Au(III) to Au(0). In this paper, Au/Al2O3 catalysts prepared by a novel incipient wetness-Mb-mediated bioreduction method were used for glucose oxidation. The catalysts were characterized, and the analysis revealed that very small gold nanoparticles with a particle size <4 nm were prepared by the incipient wetness-Mb-mediated bioreduction method, even at 1.0% Au loading (w/w). The influence of Au loading, calcination temperature and calcination time on the specific activity of Au/Al2O3 catalysts was systematically investigated. Experimental results showed that decomposing the Mb molecules properly by calcinations can enhance the specific activity of Au/Al2O3 catalysts, though they acted as reductant and protective agents during the catalyst preparation. Au/Al2O3 catalysts synthesized by the method exhibited optimum specific activity under operational synthesis conditions of Au loading of 1.0 wt % and calcined at 450 °C for 2 h. The catalysts were reused eight times, without a significant decrease in specific activity. To our knowledge, this is the first attempt at the preparation of Au/Al2O3 catalysts by Mb-mediated in situ synthesis of gold nanoparticles. 相似文献
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选用典型的非活性载体MgO、γ-Al2O3和活性载体TiO2、CeO2,采用硼氢化钠直接还原法制备4种负载型纳米金催化剂,催化甲醛氧化。结果表明,其对甲醛氧化的活性规律为Au/CeO2>Au/TiO2>Au/γ-Al2O3>Au/MgO,并对其进行了金含量、比表面测定和TEM形貌分析,为净化甲醛污染提供了有效依据。 相似文献
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Baozhu Tian Jinlong Zhang Tianzhong Tong Feng Chen 《Applied catalysis. B, Environmental》2008,79(4):394-401
Gold loaded on TiO2 (Au/TiO2) catalysts were prepared using Au(I)–thiosulfate complex (Au(S2O3)23−) as the gold precursor for the first time. The samples were characterized by UV–vis diffuse reflectance spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), and X-ray photoelectron spectroscopy (XPS) methods. Using Au(S2O3)23− as gold precursor, ultra-fine gold nanoparticles with a highly disperse state can be successfully formed on the surface of TiO2. The diameter of Au nanoparticles increases from 1.8 to 3.0 nm with increasing the nominal Au loading from 1% to 8%. The photocatalytic activity of Au/TiO2 catalysts was evaluated from the analysis of the photodegradation of methyl orange (MO). With the similar Au loading, the catalysts prepared with Au(S2O3)23− precursor exhibit higher photocatalytic activity for methyl orange degradation when compared with the Au/TiO2 catalysts prepared with the methods of deposition–precipitation (DP) and impregnation (IMP). The preparation method has decisive influences on the morphology, size and number of Au nanoparticles loaded on the surface of TiO2 and further affects the photocatalytic activity of the obtained catalysts. 相似文献
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This paper concerns the preparation of metal oxide-supported gold catalysts and their application to 2-propanol abatement in order to lower the light off temperature. Catalytic oxidation of 2-propanol was investigated on Au/CeO2, Au/Fe2O3, Au/TiO2 and Au/Al2O3 catalysts prepared from the deposition–precipitation (DP) method. The catalysts are characterized by XRD (X-ray diffraction), BET (Brunner–Emmett–Teller), TEM (transmission electron microscopy), NH3-TPD (NH3-temperature programmed desorption), H2-TPR (H2-temperature programmed reduction), ICP-AES (inductively coupled plasma-atomic emission spectroscopy) and XPS (X-ray photoelectron spectroscopy) techniques. The catalytic activity of Au/metal oxide samples towards the deep oxidation of 2-propanol to CO2 and water has been found to be strongly dependent on the kind of supports, the amount of gold loading, the calcination temperature and the moisture content in the feed. 相似文献
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采用离子交换法制备负载型纳米HZSM-5分子筛,采用负压-沉积沉淀法制备负载型纳米Au/HZSM-5催化剂,对载体及催化剂进行XRD、UV-Vis、TEM、XPS、NH3-TPD和FT-IR等表征,并评价催化剂的甲烷吸附性能。XRD与TEM表征结果表明,N2气氛焙烧的2.0%Au/HZSM-5催化剂金粒子尺寸较小,为(5~10) nm;UV-Vis表征结果表明,焙烧导致负载金的价态由离子态转为零价态,且N2气氛焙烧的2.0%Au/HZSM-5催化剂上零价金的吸收峰较弱,即相应的颗粒度较小;XPS表征结果表明,金负载量越高,催化剂上零价金占总金的比例越高;NH3-TPD表征结果表明,金负载量较小时,催化剂强酸中心峰面积较载体下降,负载量较大时,强酸和弱酸中心峰面积均下降;FT-IR表征结果表明,低温下金催化剂能将甲烷转化为含有烯烃双键的吸附物种,显示出载金催化剂对甲烷较强的C-H键活化能力。 相似文献
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Feg-Wen Chang Hsin-Yin Yu L. Selva Roselin Hsien-Chang Yang 《Applied Catalysis A: General》2005,290(1-2):138-147
Selective production of hydrogen by partial oxidation of methanol (CH3OH + (1/2)O2 → 2H2 + CO2) over Au/TiO2 catalysts, prepared by a deposition–precipitation method, was studied. The catalysts were characterized by XRD, TEM, and XPS analyses. TEM observations show that the Au/TiO2 catalysts exhibit hemispherical gold particles, which are strongly attached to the metal oxide support at their flat planes. The size of the gold particles decreases from 3.5 to 1.9 nm during preparation of the catalysts with the rise in pH from 6 to 9 and increases from 2.9 to 4.3 nm with the rise in calcination temperature up to 673 K. XPS analyses demonstrate that in uncalcined catalysts gold existed in three different states: i.e., metallic gold (Au0), non-metallic gold (Auδ+) and Au2O3, and in catalysts calcined at 573 K only in metallic state. The catalytic activity is strongly dependent on the gold particle size. The catalyst precipitated at pH 8 and uncalcined catalysts show the highest activity for hydrogen generation. The partial pressure of oxygen plays an important role in determining the product distribution. There is no carbon monoxide detected when the O2/CH3OH molar ratio in the feed is 0.3. Both hydrogen selectivity and methanol conversion increase with increasing the reaction temperature. The reaction pathway is suggested to consist of consecutive methanol combustion, partial oxidation and steam reforming. 相似文献