Pt基直接乙醇燃料电池阳极催化剂的性能研究

采用水热法制备了高分散碳载Pt/C和Pt-SnOJC电催化剂.采用XRD、SEM、TEM和激光粒度仪等方法对制得的纳米催化剂进行了表面微观结构分析.采用电化学工作站测试循环伏安曲线(CV)等表征Pt/C和Pt-SnO2/C纳米催化剂电催化活性.测试结果表明,Pt-SnO2/C纳米催化剂的峰电流密度(131.05 mA·cm-2)是Pt/C催化剂的峰电流密度(65.48 mA·cm-2)的2倍;Pt-SnO2/C催化的电化学表面积(108.4 m2·g-1)远高于Pt/C催化剂的电化学表面积(99.14 m2· g-1);Pt-SnO2/C纳米粒子比Pt/C纳米粒子具有更强的抗CO中毒能力和更高的电催化活性.     

Pt/Pt-Ce/γ-Al2O3催化氧化甲苯研究

通过等体积浸渍法制备单贵金属Pt/γ-Al₂O₃和双金属Pt-Ce/γ-Al₂O₃催化剂,考察Ce对催化剂活性的影响,确定催化剂最优配比。结果表明,当Pt的负载量为质量分数0.5%时,Pt/γ-Al₂O₃催化活性最高;当Pt的负载量为质量分数0.2%,Ce的负载量为质量分数1.0%时,Pt-Ce/γ-Al₂O₃催化剂的催化活性最高。Pt-Ce/γ-Al₂O₃催化剂的甲苯转化率高于Pt/γ-Al₂O₃催化剂。随着Pt负载量增大,催化剂孔容、孔径减小。粉体式催化剂性能优于整体式催化剂,但差别不大;Ce的添加有助于催化剂活性的提升。     

离子液体阳离子特性对铂基氧还原电催化剂性能的影响

离子液体(ILs)改性固体催化剂是一种构筑高效电催化界面的方法。为了研究ILs阳离子在催化剂中Pt表面对燃料电池中氧还原反应(ORR)性能的影响，本研究自主合成了两种疏水质子型ILs ([EIM][NTf₂],[BIM][NTf₂])和两种疏水非质子型ILs([EMIM][NTf₂],[BMIM][NTf₂])，并对商业化Pt/C进行改性。在本研究采用的咪唑类疏水ILs中，质子型ILs改性催化剂的ORR活性均高于非质子型ILs改性催化剂，其中，由1-丁基咪唑双(三氟甲磺酰)亚胺改性后的催化剂([BIM][NTf₂]@Pt/C)活性最高。在酸性半电池中ORR半波电位高达0.913 V (vs. RHE)，质量活性提升至商业化Pt/C的1.73倍，比活性提升至商业化Pt/C的3倍，同时达到5000圈循环后半波电位仅下降12 mV，性能仍高于商业化Pt/C。进一步材料表征和电化学测试表明，[BIM][NTf₂]@Pt/C电催化活性的增强归因于该ILs可增多Pt表...     

生物质焦油衍生氮掺杂多孔碳负载Co3O4纳米晶的制备及双功能氧反应催化

以生物质焦油活化多级孔碳为骨架，通过一步水热合成同时实现氮掺杂和Co₃O₄纳米粒子负载，获得Co₃O₄@N/C复合催化剂。对比研究结果表明，凭借复合材料中活性Co₃O₄和N掺杂结构之间的协同效应，Co₃O₄@N/C复合催化剂对氧还原（ORR）和析氧反应（OER）均表现出较高的催化活性，ORR和OER启动电位电势差ΔE为0.99V；其中，ORR极限扩散电流密度为-5.10mA/cm²，与贵金属Pt/C相当。此外，Co₃O₄@N/C具有优异的氧还原稳定性，在经3000次循环伏安法扫描后，Co₃O₄@N/C的极限扩散电流密度仍能保持89.9%。这一生物质焦油衍生碳所构筑的N掺杂多孔碳负载Co₃O₄纳米晶复合材料在燃料电池和金属空气电池等领域具有巨大的应用潜力。     

微乳液法制备Pt/Al2O3催化剂及其催化氯代硝基苯选择加氢活性

采用十六烷基三甲基溴化铵（CTAB）/正丁醇/环己烷/H₂PtCl₆溶液的微乳体系,以N₂H₄·H₂O为还原剂,Al₂O₃为载体制备Pt/Al₂O₃催化剂。以邻氯硝基苯（o-CNB）选择加氢反应为探针,考察微乳液组成对Pt/Al₂O₃催化剂选择加氢活性的影响。运用XRD、XPS、IR、TEM和EDS对载体和催化剂进行表征。结果表明,微乳体系中CTAB∶正丁醇∶环己烷质量比9∶21∶70,3.6% H₂PtCl₆溶液中制备的Pt/Al₂O₃催化剂的o-CNB选择加氢活性最高。Pt粒子粒径5 nm左右,与载体之间没有明显的电子效应。对于取代位置不同的间、对氯硝基苯（m-CNB、p-CNB）加氢,Pt/Al₂O₃催化剂也表现出较高的催化活性。     

添加Sm对Pt /SBA-15催化苯完全氧化反应活性和热稳定性的影响

以Pt/SBA-15为催化剂，考察催化剂载体中添加Sm对于苯的完全氧化反应活性和热稳定性影响。采用了一种简便的记录起燃温度曲线和催化剂热稳定性评价方法，即向装载好催化剂的固定床反应器中持续通入恒定流量的反应气，逐步阶段性升高反应温度，同时在线检测出口尾气的浓度变化, 得到起燃温度曲线后，继续提高反应温度，然后恒定在某一设定的温度(如550℃)持续运行较长时间, 期间定时在线取样分析，如果有必要还可以连续考察降温情况下催化剂的反应活性情况。研究结果表明，几种催化剂低温活性次序为：Pt/SBA-15≈Pt/4%Sm₂O₃/SBA-15> Pt/Sm₂O₃> 4%Sm₂O₃/SBA-15,而对于高温稳定性则是Pt/4%Sm₂O₃/SBA-15> Pt/1.2%Sm₂O₃/SBA-15> Pt/SBA-15，Pt/Sm-SBA-15(SG)> Pt/SBA-15(SG)。总之，Sm的添加虽然未能提高Pt/SBA-15的低温催化活性，但是能明显提高催化剂在高温情况下活性的稳定性。1%Pt/4%Sm₂O₃/SBA-15同时具备较好的低温催化活性和高温稳定性，具有较好的应用前景。     

负载型Pt-Fe/Al2O3催化剂用于室温催化氧化甲醛

采用胶体沉积法制备不同载体（Ni₂O₃、Co₃O₄、TiO₂、Al₂O₃）的Pt-Fe/MeO_x催化剂用于甲醛室温催化氧化。活性测试表明,以γ-Al₂O₃为载体的Pt-Fe/Al₂O₃催化剂具有较高的催化活性,在25℃时甲醛的转化率可达到100%,而且Pt-Fe/ Al₂O₃催化剂还表现出良好的稳定性。采用各种表征技术对Pt-Fe/Al₂O₃的形貌、价态及氧化还原性等物理化学性质进行了研究,结果表明：Pt-Fe/Al₂O₃催化剂中Pt物种和Fe物种在Al₂O₃载体的表面上均匀分散;二者之间存在着较强的相互作用,在Al₂O₃载体的表面上形成一些类似Pt-O-Fe活性物种,有效促进了Pt-Fe/Al₂O₃催化性能,从而显示出较高的氧化活性。     

前驱体结构对多环芳烃选择性开环Pt/Beta催化剂的影响

以海绵铂为原料合成出［Pt（NH₃）₆］Cl₄络合物,采用热重分析（TG）、扫描电镜-能谱（SEM-EDS）、紫外-可见分光光度计（UV-Vis）、质谱（MS）、X射线光电子能谱（XPS）等手段确定了［Pt（NH₃）₆］Cl₄的结构组成;以H₂PtCl₆、Pt（NH₃）₄Cl₂和［Pt（NH₃）₆］Cl₄为前驱体,采用等体积浸渍法制得Pt/Beta催化剂,采用X射线衍射（XRD）、X射线荧光光谱（XRF）、氨程序升温脱附（NH₃-TPD）、氢氧滴定（H₂-O₂）、透射电镜（TEM）、氢气程序升温脱附（H₂-TPD）等表征了Pt/Beta催化剂的物化性质,并考察了Pt/Beta催化剂的多环芳烃选择性开环性能。结果表明,［Pt（NH₃）₆］Cl₄络合物具有更高的“抗自还原”能力,可从前驱体结构上降低铂氨前驱体受热分解时的自还原现象。前驱体结构对铂纳米颗粒的几何尺寸及分布有较大影响,一方面络合物的价态显著影响前驱体与分子筛间的静电作用,进而影响铂纳米颗粒的落位与尺寸;另一方面络合物的空间结构影响前驱体在分子筛微孔中的分布,影响铂纳米颗粒的Ostwald熟化速率。前驱体结构可调变Pt/Beta催化剂的双功能匹配关系,显著影响Pt/Beta催化剂转化甲基萘的活性、稳定性,采用［Pt（NH₃）₆］Cl₄前驱体制备的Pt/Beta催化剂具有更优的活性及长周期稳定性。     

基于Nafion/GSH-Fe3O4@Cs/Pt/GCE检测丙烯酰胺

制备Nafion/还原性谷胱甘肽-四氧化三铁@碳/铂/玻碳电极（Nafion/Glutathione-ferric oxide@Carbon/Platinum/Glassy carbon electrode, Nafion/GSH-Fe₃O₄@Cs/Pt/GCE）传感器对丙烯酰胺（Acrylamide, AM）进行定量分析。合成了核壳结构的四氧化三铁@碳纳米复合材料（Ferric oxide@Carbon nanocomposites, Fe₃O₄@Cs）,并在此基础上负载铂纳米粒子（Platinum nanoparticles, Pt）,制备新型的Fe₃O₄@Cs/Pt纳米复合材料。以还原性谷胱甘肽（Glutathione, GSH）为探针,在Fe₃O₄@Cs/Pt的基础上,制备了Nafion/GSH-Fe₃O₄@Cs/Pt/GCE传感器。通过对GSH固载量、Nafi...     

Ce助剂对Pt-Sn/Ce-γ-Al2O3催化剂长链烷烃（n-C16~20）脱氢反应性能的影响

采用真空浸渍法制备了不同Ce含量的Pt-Sn/Ce-γ-Al₂O₃催化剂,采用X射线衍射、CO脉冲吸附、程序升温还原、热重及氨程序升温脱附等手段对催化剂进行表征,研究Ce助剂对Pt-Sn/Ce-γ-Al₂O₃催化剂结构及其催化长链烷烃(n-C_16~20)临氢脱氢反应性能的影响。结果表明,Ce的引入可以调变催化剂酸性,改变催化剂的还原性能;Pt、Sn和Ce以及载体之间产生较强的相互作用能够促进氧化铂的还原,提高铂粒子的热稳定性,抑制锡物种还原,降低催化剂积炭,有利于提高催化剂的脱氢活性及稳定性。     

助剂Ba对Pd/Al_2O_3和Pt/Al_2O_3催化剂的C1-C3烷烃催化燃烧性能的影响

通过浸渍法制备了Al_2O_3负载的Pd和Pt催化剂,考察催化剂的甲烷、乙烷和丙烷催化燃烧活性,以及助剂Ba对催化性能的影响。对于Pd/Al_2O_3催化剂,加入Ba使活性物种PdO颗粒变大和还原温度升高,形成更稳定的PdO活性物种,是Pd-Ba/Al_2O_3催化剂活性提升的主要原因。对于Pt/Al_2O_3催化剂,加入Ba助剂使活性物种Pt0含量降低,PtO_x与Al_2O_3载体相互作用增强,使PtO_x物种更难被还原为Pt~0,导致Pt-Ba/Al_2O_3催化剂活性降低。Pd和Pt催化剂催化烷烃氧化反应活性规律一致:丙烷乙烷甲烷。Pd/Al_2O_3催化剂有利于C—H键活化,Pt/Al_2O_3催化剂有利于C—C键活化。Pt/Al_2O_3催化剂对C1-C3烷烃氧化活性的差别明显大于Pd/Al_2O_3催化剂。Pt/Al_2O_3催化剂对碳比例高的烷烃活性更高。     

ZrO2/SiO2- and La2O3/Al2O3-supported platinum catalysts for CH4/CO2 reforming

Surface-phase ZrO₂ on SiO₂ (SZrOs) and surface-phase La₂O₃ on Al₂O₃ (SLaOs) were prepared with various loadings of ZrO₂ and La₂O₃, characterized and used as supports for preparing Pt/SZrOs and Pt/SLaOs catalysts. CH₄/CO₂ reforming over the Pt/SZrOs and Pt/SLaOs catalysts was examined and compared with Pt/Al₂O₃ and Pt/SiO₂ catalysts. CO₂ or CH₄ pulse reaction/adsorption analysis was employed to elucidate the effects of these surface-phase oxides.

The zirconia can be homogeneously dispersed on SiO₂ to form a stable surface-phase oxide. The lanthana cannot be spread well on Al₂O₃, but it forms a stable amorphous oxide with Al₂O₃. The Pt/SZrOs and Pt/SLaOs catalysts showed higher steady activity than did Pt/SiO₂ and Pt/Al₂O₃ by a factor of three to four. The Pt/SZrOs and Pt/SLaOs catalysts were also much more stable than the Pt/SiO₂ and Pt/Al₂O₃ catalysts for long stream time and for reforming temperatures above 700 °C. These findings were attributed to the activation of CO₂ adsorbed on the basic sites of SZrOs and SLaOs.     

The role of the oxidic support on the deactivation of Pt catalysts during the CO2 reforming of methane

Pt supported on γ-Al₂O₃, TiO₂ and ZrO₂ are active catalysts for the CO₂ reforming of methane to synthesis gas. The stability of the catalysts increased in the order Pt/γ-A1₂O₃ < Pt/TiO₂ < Pt/ZrO₂. For all catalysts, the decrease in activity with time on stream is caused by carbon formation, which blocks the active metal sites for reaction. With Pt/TiO₂ and Pt/ZrO₂, deactivation started immediately after the start of the reaction, while the Pt/γ-A1₂O₃ catalyst showed an induction period during which carbon was accumulated without affecting the catalytic activity.     

载体对Pt催化甲基环己烷脱氢性能的影响

采用浸渍法制备了Al₂O₃、SiO₂、Y₂O₃及活性炭负载的0.2%(质量分数,下同)Pt催化剂。氮气吸附脱附、H₂-TPR、CO脉冲吸附对催化剂表征的结果表明,活性炭载体上活性组分的分散度最高,催化甲基环己烷(MCH)脱氢反应的结果表明,活性炭负载的Pt催化剂具有最高的催化活性。     

The size effect and high activity of nanosized platinum supported catalysts for low temperature oxidation of volatile organic compounds

Pt/Al₂O₃ catalysts with smaller size of Pt nanoparticles were prepared by ethylene glycol reduction method in two different way and their oxidation activities for three typical VOCs (volatile organic compounds) were evaluated. The catalyst prepared by first adsorption and then reduction procedure is denoted as L-Pt/Al₂O₃ while the catalyst prepared by first reduction and then loading procedure is defined as R-Pt/Al₂O₃. The results show that L-Pt/Al₂O₃ with the stronger interaction between Pt species and Al₂O₃ exhibit smaller size of Pt nanoparticles and favorable thermal stability compared with R-Pt/Al₂O₃. L-Pt/Al₂O₃ is favor of the formation of more adsorbed oxygen species and more Pt²⁺ species, resulting in high catalytic activity for benzene and ethyl acetate oxidation. However, R-Pt/Al₂O₃ catalysts with higher proportion of Pt⁰/Pt²⁺ and bigger size of Pt particles exhibits higher catalytic activity for n-hexane oxidation. Pt particles in R-Pt/Al₂O₃ were aggregated much more serious than that in L-Pt/Al₂O₃ at the same calcination temperature. The Pt particles supported on Al₂O₃ with~10 nm show the best catalytic activity for n-hexane oxidation.     

Comparative study of Pt-based catalysts on different supports in the low-temperature de-NOx-SCR with propene

Pt-based catalysts have been prepared using supports of different nature (γ-Al₂O₃, ZSM-5, USY, and activated carbon (ROXN)) for the C₃H₆-SCR of NO_x in the presence of excess oxygen. Nitrogen adsorption at 77 K, pH measurements, temperature-programmed desorption of propene, and H₂ chemisorption were used for the characterization of the different supports and catalysts. The performance of these catalysts has been compared in terms of de-NO_x activity, hydrocarbon adsorption and combustion at low temperature, and selectivity to N₂. Maximum NO_x conversions for all the catalysts were achieved in the temperature range of 200–250°C. The order of activity was, Pt-USY>Pt/ROXNPt-ZSM-5Pt/Al₂O₃. At temperatures above 300°C only Pt/ROXN maintains a high activity caused by the consumption of the support, while the other catalysts present a strong deactivation. Propene combustion starts at the same temperature for all the catalytic systems (160°C). Complete hydrocarbon combustion is directly related to the acidity of the support, thus determining the temperature of the maximum NO_x reduction. The support play an important role in the reaction mechanism through the hydrocarbon activation. N₂O formation was observed for all the catalysts. N₂ selectivity ranges from 15 to 30% with the order, Pt/ROXN>Pt-USYPt/Al₂O₃>Pt-ZSM-5. The catalytic systems exhibit a stable operation under isothermal conditions during time-on-stream experiments.     

Ultrahigh temperature water gas shift catalysts to increase hydrogen yield from biomass gasification

Noble metal (Rh, Pt, Pd, Ir, Ru, and Ag) and Ni catalysts supported on CeO₂–Al₂O₃ were investigated for water gas shift reaction at ultrahigh temperatures. Pt/CeO₂–Al₂O₃ and Ru/CeO₂–Al₂O₃ demonstrated as the best catalysts in terms of activity, hydrogen yield and hydrogen selectivity. At 700 °C and steam to CO ratio of 5.2:1, Pt/CeO₂–Al₂O₃ converted 76.3% of CO with 94.7% of hydrogen selectivity. At the same conditions, the activity and hydrogen selectivity for Ru/CeO₂–Al₂O₃ were 63.9% and 85.6%, respectively. Both catalysts showed a good stability over 9 h of continuous operation. However, both catalysts showed slight deactivation during the test period. The study revealed that Pt/CeO₂–Al₂O₃ and Ru/CeO₂–Al₂O₃ were excellent ultrahigh temperature water gas shift catalysts, which can be coupled with biomass gasification in a downstream reactor.     

Synergistic catalysis of carbon black oxidation by Pt with MoO3 or V2O5

A series of SiO₂-supported MoO₃, V₂O₅, and Pt catalysts were prepared for the study of model soot oxidation with simulated diesel exhaust gas. Composite samples of Pt with the metal oxides demonstrated higher oxidation activities than the single-component SiO₂-supported MoO₃, V₂O₅ or Pt catalysts in the absence of SO₂ in the reactant gas. Based on the effects of NO₂ on carbon oxidation, a synergistic reaction mechanism was suggested to explain the effects of combining Pt with the oxides: Pt catalyzes the oxidation of NO with gas phase O₂ to NO₂, while MoO₃ and V₂O₅ catalyze the oxidation of carbon with NO₂. Finally, the effects of SO₂ on the carbon oxidation reaction were examined and discussed.     

PtSn负载量对PtSn/Al2O3催化剂上丙烷脱氢性能的影响

由丙烷直接催化脱氢制取丙烯已经成为增产丙烯的重要手段之一。以水热法制备Al_2O_3载体,采用等体积浸渍法制备不同PtSn负载量的PtSn/Al_2O_3催化剂。通过XRD、N2-吸附、拉曼光谱和H2-TPR等对其进行表征,并考察不同PtSn负载量对催化剂催化丙烷脱氢性能的影响。结果表明,在制备的催化剂中,Pt1.5Sn3/Al_2O_3具有最高的催化丙烷脱氢活性和稳定性,丙烷初始转化率高达55.6%,丙烯选择性98.1%。反应330 min后,丙烷转化率仅降约10%,选择性保持不变。     

Transient studies of carbon dioxide reforming of methane over Pt/ZrO2 and Pt/Al2O3

The mechanism of the CO₂ reforming of methane reaction over the Pt/ZrO₂ catalyst was investigated using a temporal analysis of products (TAP) reactor system. For comparative purposes, the reaction pathway using a Pt/Al₂O₃ catalyst was also examined. A reaction sequence is suggested for both catalysts. Over both catalysts, methane decomposition takes place over platinum. The main difference between the two catalysts concerns the carbon dioxide dissociation. Over Pt/Al₂O₃ this step is assisted by hydrogen. Over Pt/ZrO₂ this step takes place over the zirconia support and involves surface vacancies. Moreover, large pools of formate and carbonate species are present on the zirconia. Transient studies conducted to determine the origin of carbon species accumulated during CO₂ reforming revealed that more than 99% of the carbon was derived from the methane molecule over both catalysts. Over the Pt/ZrO₂ catalyst, only a single very reactive carbon species was detected, while over the Pt/Al₂O₃ a second less active species was also formed.