不同方法制备的碳载Pt-TiO_2催化剂对甲醇的电催化氧化

采用TiO2溶胶法,在不同条件下制备了碳载Pt-TiO2催化剂。运用循环伏安法、线性扫描法和计时电流法来检测甲醇在不同方法制备的碳载Pt-TiO2催化剂上的电催化氧化情况。结果发现,在酸性溶液中方法a制备的碳载Pt-TiO2催化剂对甲醇的电氧化有良好的催化活性和稳定性。     

碳载Pt-TiO2催化剂对甲醇的电催化氧化

采用TiO2溶胶法,选用3种不同还原剂(甲酸、甲醛、硼氢化钠)制备了碳载Pt-TiO2催化剂。通过XRD衍射,循环伏安法(CV)和计时电流法(CA)对碳载Pt-TiO2催化剂的结构及其对甲醇的电氧化特性进行了研究。结果表明不同还原剂制备的催化剂中,TiO2的结晶度不同,Pt的粒径不同,电化学比表面不同,对甲醇的电催化氧化的催化活性也不同。其中用甲酸还原所制得的碳载Pt-TiO2催化剂对甲醇的电催化氧化活性分别是采用甲醛或硼氢化钠方法的1.41倍和1.76倍。     

碳载Pt-TiO2对乙醇的电催化氧化

用简单的化学沉积法制备了碳载Pt(Pt/C)和碳载Pt-TiO2(Pt-TiO2/C)催化剂。研究发现无论是25℃还是60℃与Pt/C电极相比,乙醇在Pt-TiO2/C电极上的起始氧化电位及氧化峰电位均比在Pt/C电极上负移。而在中性溶液中,乙醇在Pt-TiO2/C电极上的氧化峰电流密度比并在Pt/C催化剂有一定程度的增大。     

甲醇燃料电池阳极催化剂的试验

用化学还原法制备了碳载镍、银、金三种金属单质催化剂,并研究其对甲醇电催化氧化的活性。用X射线衍射光谱（XRD）、X光电子能谱（XPS）表征催化剂的晶相结构、表面组成及价态形式。XRD测试表明均得到了纯度较高的金属单质,催化剂粒径大小在5 nm-11nm之间,颗粒分布均匀。用循环伏安法测定了不同催化剂对甲醇的电催化氧化的活性,结果表明碳载镍催化剂对甲醇氧化有较好的催化作用,而碳载银和碳载金对甲醇氧化几乎没有活性。     

碱性条件下甲醇阳极氧化碳载催化剂的性能

用化学还原法制备了碳载镍、银、金三种金属单质催化剂,并研究其对甲醇电催化氧化的活性.用X射线衍射光谱(XRD)、X光电子能谱(XPS)表征催化剂的晶相结构、表面组成及价态形式.XRD测试表明均得到了纯度较高的金属单质,催化剂粒径大小在5～11 nm之间,颗粒分布均匀.用循环伏安法测定了不同催化剂对甲醇的电催化氧化的活性...     

乙二醇稳定的Pt/C催化剂的制备与表征

以乙二醇(EG)兼作溶剂和稳定剂,分别通过NaBH4和EG还原法制备了高度细化与分散的Pt/C催化剂,对其形貌、组成、结构和电化学活性比表面等进行了表征比较,并测试了它们对甲醇与乙醇电催化氧化的活性. 结果表明,2种催化剂中,Pt均为面心立方结构,粒径小且分布窄,在炭黑载体上分散均匀,单位质量Pt对甲醇与乙醇电催化氧化的活性相当;NaBH4还原法所制Pt/C催化剂中Pt0和Pt(220)晶面含量更高,Pt对甲醇与乙醇电催化氧化的峰电流密度分别为0.68与0.67 mA/cm2,分别是EG还原法所制Pt/C催化剂的1.2倍;2种催化剂对甲醇与乙醇电催化氧化的活性均与商品E-TEK催化剂相当.     

RuAg/TiO2-C催化剂的制备及对甲醇的电催化氧化性能

采用改性溶胶-凝胶法和水热合成法制备了C掺杂多孔纳米TiO2,以其为载体制备了一种RuAg/TiO2-C催化剂.采用XRD、TEM、EDS、XPS及电化学分析对催化剂的结构和性能进行了表征,测定了其对甲醇的电催化氧化性能.结果表明,RuAg的负载和C的掺杂提高了TiO2对甲醇的电催化性能,RuAg/TiO2-C对甲醇电催化的循环伏安曲线中未见甲醇氧化中间产物的氧化峰,0.54 V处有一个较大的甲醇氧化峰,其峰电流密度为5.8 mA/cm2,RuAg/TiO2-C比商用PtRu/C催化剂具有更高的催化活性和抗毒性,RuAg合金的负载以及RuAg合金与C掺杂多孔纳米TiO2载体之间较强的相互作用是其对甲醇催化性能提高的主要因素.     

碳化钨/碳气凝胶纳米复合材料增强Pt电催化甲醇性能的研究

以间苯二酚和甲醛为原料,采用溶胶-凝胶法原位合成WC纳米颗粒制备了碳化钨/碳气凝胶(WC/CAs);以WC/CAs为载体,利用微波加热乙二醇还原法制备了Pt/WC/CAs催化剂。运用循环伏安法(CV)、线性扫描(LSV)、计时电流法(CA)、能谱(EDS)、透射电子显微镜(TEM)和X射线衍射(XRD)等技术分析Pt/WC/CAs催化剂的组成、结构及其对甲醇的电催化氧化活性的影响。实验结果表明,载体中WC纳米颗粒的加入促进Pt贵金属颗粒对甲醇的电催化氧化活性,正扫电流峰ip与扫描速率的平方根v1/2线性相关,Pt/WC/C催化氧化甲醇的过程受扩散控制;且电催化活性比Pt/C要好。     

F掺杂TiO_2的制备及其甲醇电氧化性能研究

采用水热法制备了F掺杂的TiO2,将其与碳黑机械混合制成复合载体,采用微波辅助加热乙二醇法制备了载Pt电催化剂。通过X射线衍射(XRD)和扫描电镜(SEM)对F-TiO2进行了表征,结果表明,F掺杂后,TiO2仍然呈锐钛矿结构,形貌呈纳米片层结构。Pt/F-TiO2-C催化剂表现出很好的催化活性和稳定性,循环伏安法和计时电流法的测试结果表明,复合载体中F的加入有利于甲醇的电催化氧化,提高了Pt对甲醇氧化的抗毒化能力,使其质量比活性是商业Pt/C催化剂的1.2倍。     

微波法制备的Pt/C催化剂对甲醇和CO的电催化氧化

用微波间断升温法制备了3种Pt/C催化剂,运用循环伏安和线行扫描方法测试甲醇和吸附态CO在不同方法制备的Pt/C催化剂上的电催化氧化情况。发现在酸性溶液中,对于相同Pt载量的Pt(2)和Pt(3)催化剂,Pt(3)具有较小的Pt平均粒径及较高的电催化活性;对于具有较高Pt载量的Pt(1)催化剂,具有最小的平均粒径和最高的电催化活性。     

可见光响应Pt掺杂纳米TiO2的光催化氧化NOx性能

采用溶胶-凝胶法制备不同Pt掺杂比例的Pt-TiO2光催化剂。通过XRD、XPS、UV-vis表征光催化剂结构,在紫外光及可见光下考察其对NOx的光催化氧化活性。结果表明,所制备的Pt-TiO2均为锐钛矿相,对NOx有明显的可见光降解效果,并且以Pt/Ti比为0.4%时,其光催化活性最高。与P25及TiO2相比,Pt-TiO2在紫外光及可见光下的光催化活性均有较大提高,其NO转化率明显提高,NO2选择性生成率明显降低,归因于Pt的掺杂引入了杂质能级并促进了催化剂的光生电子-空穴对的分离。     

不同载体成型的ZSM-5催化剂上甲醇芳构化反应性能

以ZSM-5分子筛为活性组分,采用不同的氧化物载体挤条制备催化剂,并对催化剂的甲醇芳构化反应性能进行评价。采用X射线衍射、氨程序升温脱附和N₂低温吸附-脱附等方法对催化剂进行表征。结果表明,添加氧化物载体后,催化剂的芳构化反应性能明显提高,催化剂芳构化反应性能与其酸性质有着密切联系,Zn/La-ZSM-5(Al₂O₃)催化剂的芳构化反应性能较好,主要归因于催化剂具有适宜的酸分布和孔结构。在反应压力0.1 MPa、空速0.8 h^-1、反应温度437 ℃和反应时间240 min条件下,轻质芳烃收率为42.36%.     

Hydrogenation of carbon dioxide over copper-pyrochlore/zeolite composite catalysts

The hydrogenation of CO₂ was studied over composite catalysts obtained by mixing Cu-based methanol synthesis catalyst and HY zeolite. A mechanism associating methanol synthesis and MTG (methanol to gasoline) reaction allowed the formation of C₁-C₄ hydrocarbons. It was found that the catalytic behaviors of the composite catalysts were favorably influenced by the characteristics of the methanol synthesis catalysts. The Cu-La₂Zr₂O₇ catalyst we recently developed associated with HY zeolite exhibited interesting performances in hydrocarbon synthesis. The addition of ZrO₂ to Cu---La₂Zr₂O₇/HY enhanced the ability to produce hydrocarbons. Comparing composite catalyst systems prepared with different Cu-based methanol synthesis catalysts, the effect of Na contamination on methanol and hydrocarbon formation over composite catalysts were also discussed.     

Ignition of methanol partial oxidation over supported platinum catalyst

Supported platinum catalysts were prepared by precipitation of H₂PtCl₆ on powders of different metal oxides. Catalytic activity of the prepared catalysts was tested with reaction of partial oxidation of methanol (POM) for hydrogen production. Most of the prepared catalysts can ignite POM at the ambient temperature. The conversion of methanol and the selectivity of hydrogen and carbon monoxide, however, increased with the reaction temperature and varied with the kind of support and platinum loading. A 1 wt% Pt/ZnO catalyst exhibited optimized methanol conversion and selectivity at a low reaction temperature of 150 °C. The reactor may reach this temperature within 2 min after a start of the exothermic reaction.     

Preparation of Pt/CeO2/HCSs anode electrocatalysts for direct methanol fuel cells

Hollow carbon spheres (HCSs) were prepared through a simple hydrothermal method using silica particles and glucose as the template and carbon precursor, respectively. HCSs used as supports for platinum catalysts deposited with cerium oxide (CeO₂) were prepared for application as anode catalysts in direct methanol fuel cells. The composition and structure of the samples were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The electrocatalytic properties of the as-prepared catalysts for methanol oxidation were investigated by cyclic voltammetry (CV). The Pt/CeO₂/HCSs catalyst heated at 550 °C for 1 h exhibited the best catalytic activity for methanol oxidation.     

Preparation of Cu/ZrO2 catalysts for methanol synthesis from CO2/H2

Cu/ZrO₂ catalysts for methanol synthesis from CO₂/H₂ were respectively prepared by deposition coprecipitation (DP) and solid state reaction (SR) methods. There is an intimate interaction between copper and zirconia, which strongly affects the reduction property and catalytic performance of the catalysts. The stronger the interaction, the lower the reduction temperature and the better the performance of the catalysts. Surface area, pore structure and crystal structure of the catalysts are mainly controlled by preparation methods and alkalinity of synthesis system. The conversion of CO₂ and selectivity of methanol are higher for DP catalysts than for SP catalysts.     

W/O微乳液法制备Ni-Zr/Pani电催化剂及其性能

通过反相微乳液法(W/O)制备了金属质量分数为40%的不同原子比的Ni-Zr/Pani催化剂。采用SEM和XRD分析了催化剂的形态,循环伏安法考察了催化剂对甲醇的电催化性能。结果表明,当微乳液ω=7.52制备的Ni和Zr原子比=1∶〖KG-*2〗1时,催化剂成球形非晶态,在常温2 mol·L^-1的甲醇硫酸溶液中,Ni₁Zr₁/Pani表现出较好的电催化性能,其氧化电位为1.046 V,氧化电流密度为4.44 mA·cm^-2。     

Niobic acid and niobium phosphate as highly acidic viable catalysts in aqueous medium: Fructose dehydration reaction

All silicious MCM-41 was investigated as a support or a support precursor for Pd/SiO₂ and prepared catalysts were tested for methanol synthesis from CO and H₂. The methods of Pd loading on the MCM-41 were impregnation, seed impregnation and chemical vapor deposition (CVD). For both impregnations, most Pd existed outside of the pore as large particles, and only a small part of Pd was inserted into the pore of MCM-41 retaining the initial structure. On the contrary, in the catalyst prepared by CVD method, the MCM-41 structure was completely destroyed to become amorphous SiO₂. Yet the average Pd particle size in this catalyst was smaller and its distribution was narrower than those of the catalysts prepared by impregnation methods. In the methanol synthesis from CO hydrogenation the catalyst prepared by CVD showed higher methanol selectivity than other MCM-41-derived catalysts. This result was considered to be due to the more uniform distribution of the Pd particle size.