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采用溶胶固定法制备了一系列的Au/C纳米催化剂,进行了透射电镜(TEM)表征,用于常压下以氧气为氧化剂碱性溶液中葡萄糖氧化制备葡萄糖酸钠,并对最佳的催化剂进行了反应条件影响考察。结果显示,使用溶胶固定法制备的质量分数为1%的Au/C催化效果最佳,纳米金颗粒直径小于2 nm且分布均匀,其较佳反应条件为50℃,pH 9.5,氧气流量40 mL/min,催化剂0.22 g,水溶液中质量分数为7.5%的葡萄糖,葡萄糖在1 h内,选择性及转化率均可同时达到100%,反应的转化频率(Turnover Frequency,TOF)高达1 560 h-1。上述研究表明溶胶固定法能制备一定纳米金颗粒大小的Au/C催化剂,且在该多相催化剂上反应时间短,活性高,选择性高。 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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《化工进展》2017,(11)
催化剂壁载化是在微通道反应器内负载催化剂的有效方法,适用于氨氧化过程这一强放热气固反应体系,但不同的催化剂壁载化后其催化性能还有待研究。本研究通过将Pt、Pd、Au 3种贵金属通过光催化沉积方法负载于TiO_2纳米管上并组装入微通道反应器内,考察了其催化氨氧化过程性能,并通过密度泛函方法解释了其性能差异。结果证实,TiO_2载体对催化过程无明显影响,3种催化剂催化活性顺序为Pt/TiO_2Pd/TiO_2Au/TiO_2,其中Pt/TiO_2氨转化率在280℃下即可达100%,NO选择性380℃即达99%。TPD检测及模拟证实,NH3及O2在催化剂表面吸附能大小顺序为PtPdAu,与催化活性顺序一致。 相似文献
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探索Au纳米粒子对新型材料的催化性能可以显著拓宽金催化剂的应用范围。使用TiO2-B作为载体,担载Au纳米粒子并应用于低温CO氧化反应体系。TiO2-B为长度5~20 mm的微米级纤维,Au纳米粒子粒径在3 nm以下,均匀地分散在TiO2-B表面。CO 氧化测试表明,Au纳米粒子的性能受TiO2-B焙烧温度的影响,不同焙烧温度会引起Au分散性以及Au纳米粒子与载体相互作用的改变。分散于纯TiO2-B载体上的金的催化活性可与其分散在锐钛矿纳米粉体上的相媲美。此外,300℃下活化的Au纳米粒子表现出了最佳的CO氧化性能,在氧化性气氛中活化的催化剂的催化性能优于在惰性和还原性气氛中活化的催化剂。 相似文献
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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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使用沉淀沉积法及溶液浸渍法分别将Au和Pd纳米粒子负载在原子层沉积法制备的1cTiO2/SiO2载体上,制备出两种不同Pd负载量的Pd-Au双金属活性中心纳米催化剂。采用TEM、EDX、XPS对所制备的催化剂进行了详细的表征,确定了纳米粒子的形貌、Pd-Au元素的化学价态和组成。测试了该类催化剂在以氧气为氧源的环己烯环氧化反应中的活性和选择性,并对反应溶剂、共还原剂种类、反应温度等条件进行了筛选。在优化后的反应条件下考察了该催化剂对不同结构烯烃的适用性。对于环状烯烃,底物转化率均大于95%,环氧产物选择性均大于91%。催化剂在循环回收5次后,催化活性和反应选择性保持不变。 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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《Catalysis communications》2007,8(1):57-64
Au, Ag and Au–Ag catalysts on different supports of alumina, titania and ceria were studied for their catalytic activity of ethylene oxidation reactions. An addition of an appropriate amount of Au on Ag/Al2O3 catalyst was found to enhance the catalytic activity of the ethylene epoxidation reaction because Au acts as a diluting agent on the Ag surface creating new single silver sites which favor molecular oxygen adsorption. The Ag catalysts on both titania and ceria supports exhibited very poor catalytic activity toward the epoxidation reaction of ethylene, so pure Au catalysts on these two supports were investigated. The Au/TiO2 catalysts provided the highest selectivity of ethylene oxide with relatively low ethylene conversion whereas, the Au/CeO2 catalysts was shown to favor the total oxidation reaction over the epoxidation reaction at very low temperatures. In comparisons among the studied catalysts, the bimetallic Au–Ag/Al2O3 catalyst is the best candidate for the ethylene epoxidation. The catalytic activity of the gold catalysts was found to depend on the support material and catalyst preparation method which govern the Au particle size and the interaction between the Au particles and the support. 相似文献
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Gold particles supported on carbon and titania were explored as catalysts for oxidation of CO or glycerol by O2 at room temperature in liquid-phase water. Although Au/carbon catalysts were not active for vapor phase CO oxidation at room
temperature, a turnover frequency of 5 s−1 could be achieved with comparable CO concentration in aqueous solution containing 1 M NaOH. The turnover frequency on Au/carbon
was a strong function of pH, decreasing by about a factor of 50 when the pH decreased from 14 to 0.3. Evidently, a catalytic
oxidation route that was not available in the vapor phase is enabled by operation in the liquid water at high pH. Since Au/titania
is active for vapor phase CO oxidation, the role of water, and therefore hydroxyl concentration, is not as significant as
that for Au/carbon. Hydrogen peroxide is also produced during CO oxidation over Au in liquid water and increasing the hydroxyl
concentration enhances its formation rate. For glycerol oxidation to glyceric acid (C3) and glycolic acid (C2) with O2 (1–10 atm) at 308–333 K over supported Au particles, high pH is required for catalysis to occur. Similar to CO oxidation
in liquid water, H2O2 is also produced during glycerol oxidation at high pH. The formation of the C-C cleavage product glycolic acid is attributed
to peroxide in the reaction. 相似文献
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Abatement of volatile organic compounds: oxidation of ethanal over niobium oxide-supported palladium-based catalysts 总被引:1,自引:0,他引:1
Niobium-supported palladium-based catalysts (Pd, Pd–Cu and Pd–Au) were employed in the oxidation of ethanal. The catalysts were prepared according to original methods by either multi-steps (anchoring of complexes, calcination and reduction) or one-step (photoassisted reduction) procedures. The oxidation of ethanal was carried out in gas phase in a dynamic-differential reactor at 300 °C at atmospheric pressure. The activity/selectivity of the catalysts depend on (i) the catalyst preparation; (ii) the presence of a second metal. Addition of Au or Cu decreases the catalysts deactivation and the best performance in total oxidation was obtained with Pd–Au/Nb2O5 prepared by photoassisted reduction. As shown by in situ IR spectroscopy of adsorbed CO, this peculiarity may be ascribed to Au→Pd electron donation, which prevents the surface oxidation of palladium particles. 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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A significant enhancement in the catalytic activity of Au/TiO2 in CO oxidation and preferential oxidation reaction by creating the active sites on the catalyst surface by thermal treatment as well as by producing small gold particles by plasma treatment has been studied. Au/TiO2 catalyst (Au (1 wt%) supported on TiO2) was prepared by conventional deposition-precipitation method with NaOH (DP NaOH) followed by washing, drying and calcination in air at 400 °C for 4 h. Thermal treatment of Au/TiO2 was carried out at 550 °C under 0.05 mTorr. A small amount of Au/TiO2 catalyst was taken from the untreated and thermally treated Au/TiO2 and both kinds of catalysts were treated with plasma sputtering at room temperature. The activity of the catalysts has been examined in the reaction of CO oxidation and preferential oxidation (PROX) at 25–250 °C. Thermally treated Au/TiO2 showed better catalytic activity as compared to the untreated catalyst. There is also an additional enhancement in the catalytic activity due to plasma sputtering on the both kinds of catalysts. Thermally treated Au/TiO2 followed by plasma sputtering Au/TiO2 showed higher conversion rates for CO oxidation reaction compared with untreated, thermally treated and plasma sputtered Au/TiO2 catalysts. It may be concluded that the enhancement of catalytic activity of thermally treated Au/TiO2 followed by plasma sputtering is owing to the generation of active sites such as oxygen vacancies/defects in TiO2 support using thermal treatment as well as by producing small gold particles using plasma treatment. 相似文献
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Xiao-Ying Wang Shu-Ping Wang Shu-Rong Wang Ying-Qiang Zhao Jing Huang Shou-Min Zhang Wei-Ping Huang Shi-Hua Wu 《Catalysis Letters》2006,112(1-2):115-119
Au/CeO2 catalysts prepared by co-precipitation (CP) and deposition-precipitation (DP) methods were tested for low temperature CO
oxidation reaction. The structural characters and redox features of the catalysts were investigated by XRD, XPS and H2-TPR. Their catalytic performances for low temperature CO oxidation were studied by means of a microreactor -GC system. It
showed that the catalytic activities of Au/CeO2 catalysts greatly depended on the preparation method. The catalysts prepared by DP method exhibited a surprisingly higher
activity towards CO oxidation than that prepared by CP method. This may arise from the differences in the particle sizes of
Au and redox properties of the catalysts. The low Au loading and the resistance to high temperature of DP-prepared catalyst
made it more applicable. 相似文献
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Highly Active Au/TiO2 Catalysts for Low-Temperature CO Oxidation: Preparation, Conditioning and Stability 总被引:1,自引:0,他引:1
Using a modified depositionprecipitation procedure and a new reductive conditioning method, Au/TiO2 catalysts with small metallic Au particles (<2 nm) and a very high activity for low-temperature CO oxidation were prepared. The particles are stable during reaction; a decreasing activity is caused by the accumulation of by-products on the catalyst. 相似文献