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1.
CuO/活性炭和Fe2O3/活性炭催化还原NO   总被引:4,自引:0,他引:4  
高志明  赵震 《应用化学》1996,13(4):77-79
CuO/活性炭和Fe_2O_3/活性炭催化还原NO高志明,赵震,杨向光,吴越(中国科学院长春应用化学研究所长春130022)关键词活性炭,还原,NO,氧化铜,氧化铁目前,对固定源的NO处理是采用V2O5/TiO2作催化剂,NH3作还原剂的选择催化还原方...  相似文献   

2.
The adsorption of poly[N-(m- and p-vinylbenzyl)-N,N,N-trimethylammonium tetrachloropal-ladate] complex on inorganic oxide surfaces followed by reduction of the palladium salt to form a catalytically active zerovalent metal polymer composite dispersed on the oxide surface and further deposition of transition metals, e.g., nickel, cobalt, and copper, by “additive” or “subtractive” deposition from electroless plating solutions is described. γ-Ferric oxide was used as a template for such intermetallic replacement reactions, providing materials with controlled amounts of metal. Multimetallic catalysts based on aluminum oxide, zinc oxide, lanthanum oxide, magnesium oxide, and silica were prepared. Iron oxide modified by subtractive deposition of rhodium and iridium on nickel-clad iron oxide were evaluated in Fischer–Tropsch carbonylation reactions leading from synthesis gas to alkanols.  相似文献   

3.
纳米氧化亚铜的制备及其电化学性质   总被引:5,自引:0,他引:5  
研究了纳米氧化亚铜的软模板制备法,并用XRD和TEM对所制备的纳米氧化亚铜进行了表征.试验表明,利用十六烷基三甲基溴化胺为软模板制备的纳米氧化亚铜呈直径为10 nm左右,长度为250 nm左右的纳米晶须.利用Nafion将新制备的纳米氧化亚铜固定在玻碳电极表面,研究了纳米氧化亚铜的电化学性质.结果表明,纳米氧化亚铜在电极表面表现出一对对称性良好的氧化还原峰,对应于纳米氧化亚铜中心的Cu(Ⅱ)/Cu(Ⅰ)的氧化还原,峰电流随扫描速度的增大呈现线性关系,根据峰电位与扫速对数的线性关系,计算出了电子转移系数.表明纳米氧化亚铜在电极表面的反应是受表面控制的部分不可逆过程.  相似文献   

4.
臭氧化物生成机理研究综述   总被引:7,自引:0,他引:7  
沙耀武  王欣 《有机化学》1999,19(3):224-235
以Criegee三步反应机理为核心对烯烃臭氧化反应中的臭氧化物生成机理进行了综述。论述了初级臭氧化物的生成与分解和臭氧化物生成过程的选择性和立体化学。讨论了烯烃结构和反应各步骤的选择性和立体化学的关系。  相似文献   

5.
The reduction of thick oxide films formed on Pt under severe anodic conditions was studied in the presence of adsorbed I?. The Pt electrode covered with a thick oxide film does not adsorb I?. However, when a superficial monolayer oxide on the thick oxide has been reduced, I? is irreversibly adsorbed. Iodide adsorbed on its surface blocks the adsorption of hydrogen and retards markedly the cathodic reduction of the inner thick oxide remaining. It was found that the reduction rate of the inner oxide depends only on the coverage by hydrogen, which coexists with adsorbed I?. These results support the proton-electron theory which has previously been proposed for the explanation of the characteristic reduction of the thick oxide films.  相似文献   

6.
Cellular patterning on silicon platforms is the basis for development of integrated cell-based biosensing devices, for which long-term cell selectivity and biostability remain a major challenge. We report the development of a silicon-based platform in a metal-insulator format capable of producing uniform and biostable cell patterns with long-term cell selectivity. Substrates patterned with arrays of gold electrodes were surface-engineered such that the electrodes were activated with fibronectin to mediate cell attachment and the silicon oxide background was passivated with PEG to resist protein adsorption and cell adhesion. Three types of oxide surfaces, i.e., native oxide, dry thermally grown oxide, and wet thermally grown oxide, were produced to illustrate the effect of oxide state of the surface on long-term cell selectivity. Results indicated that the cell selectivity over time differed dramatically among three patterned platforms and the best cell selectivity was found on the dry oxide surface for up to 10 days. Surface analysis results suggested that this enhancement in cell selectivity may be related to the presence of additional, more active oxide states on the dry oxide surface supporting the stability of PEG films and effectively suppressing the cell adhesion. This research offers a new strategy for development of stable and uniform cell-patterned surfaces, which is versatile for immobilization of silane-based chemicals for preparation of biostable interfaces.  相似文献   

7.
Potential sweep techniques were used to investigate the anodic behaviour of reduced ruthenium surfaces, prepared by electrodeposition on gold-plated substrates, as a function of sweep rate, temperature and pH. The most important factor appeared to be pH as this strongly influenced the oxide layer thickness and both the number and location of the peaks on the voltammogram. The formation of thin oxide films on ruthenium at intermediate pH values (3.5–9.5) is attributed to the growth of a compact amorphous film with significant metal-oxygen-metal bridging in the structure. Heavier oxide growth in strong acid is attributed to protonation of the oxide lattice resulting in the formation of a more porous anodic film. Thicker oxide growth in strong base is attributed to the growth of a higher (+6) oxide under these conditions. The effects of both sweep rate and temperature on anodic behaviour in strong acid are attributed to activation-controlled rearrangement of the oxide film.  相似文献   

8.
纳米TiO2-SiO2复合氧化物的制备与性质   总被引:32,自引:0,他引:32  
采用溶胶-凝胶结合CO2超临界干燥方法制备了比表面积大、热稳定性好的纳米TiO2-SiO2复合氧化物.考察了原料组成和焙烧温度对复合氧化物比表面积、热稳定性和酸性的影响,通过加氢脱硫反应考察了该复合氧化物作为加氢精制催化剂载体的可行性.结果表明,采用该方法制备的复合氧化物为纳米颗粒,在n(Ti)/n(Si)=1时,其比表面积和孔容最大;与纯TiO2相比,引入SiO2明显提高了复合氧化物的热稳定性和晶型稳定性;以此复合氧化物为载体的加氢精制催化剂具有很好的低温脱硫活性,TiO2-SiO2复合氧化物载体的酸性特征影响了催化剂的加氢脱硫活性.  相似文献   

9.
为用现代表面科学技术研究金属氧化物催化剂,在Pt(111)上于超高真空系统中原位蒸镀制备了NbO、NbO2、NbO2、单晶薄膜(>2nm).通过AES、ISS、LEED、ILS等手段研究了单晶薄膜的成长模式、化学计量和几何结构.表明通过选择合适的废物和控制制备条件,可制备出确定结构的金属氧化物单晶薄膜表面作为体相氧化物催化剂的模型表面.这种方法克服了电子能谱技术研究金属氧化物表面的困难,为研究金属氧化物催化剂的表面化学物理性质提供了方法  相似文献   

10.
The tin oxide and silicon oxide films have been deposited on polycarbonate substrates as gas barrier films, using a thermal evaporation and ion beam assisted deposition process. The oxide films deposited by ion beam assisted deposition show a much lower water vapor transmission rate than those by thermal evaporation. The tin oxide films show a similar water vapor transmission rate to the silicon oxide films in thermal evaporation but a lower water vapor transmission rate in IBAD. These results are related to the fact that the permeation of water vapor with a large dipole moment is affected by the chemistry of oxides and the packing density of the oxide films. The permeation mechanism of water vapor through the oxide films is discussed in terms of the chemical interaction with water vapor and the microstructure of the oxide films. The chemical interaction of water vapor with oxide films has been investigated by the refractive index from ellipsometry and the OH group peak from X-ray photoelectron spectroscopy, and the microstructure of the composite oxide films was characterized using atomic force microscopy and a transmission electron microscope. The activation energy for water vapor permeation through the oxide films has also been measured in relation to the permeation mechanism of water vapor. The diffusivity of water vapor for the tin oxide films has been calculated from the time lag plot, and its implications are discussed.  相似文献   

11.
The effects of pulsating current and voltage sources with different magnitudes on an oxide film formed by microarc oxidation (MAO) of AZ31B magnesium alloy in alkaline metal silicate solution were investigated. The thickness of an oxide film increased with increasing current source but the uniformity of the surface of an oxide film became worse. The unstable oxidation process represented by fluctuating voltage established across an oxide film was discussed and related to the surface roughness and the melting down of magnesium alloy. By comparing the surface of an oxide film a pulsating current source produced more uniform oxide film on magnesium alloy than a pulsating voltage source.  相似文献   

12.
The method of the chemical synthesis of reduced graphene oxide was developed. Sodium hypophosphite and sulfi te were used as reducing agents. The formation of reduced graphene oxide was confi rmed by several methods. Volt-ampere characteristics of electrodes based on reduced graphene oxide were investigated in an experimental model of an oxygen fuel cell with an alkaline electrolyte. Characteristics of oxygen electrodes based on reduced graphene oxide were stable over semiannual tests. The resulting reduced graphene oxide is a promising material for oxygen electrodes of chemical current sources.  相似文献   

13.
The electrochemical reduction of multilayer oxides which were formed on a smooth Pt electrode surface under severe anodic conditions was investigated using a galvanostatic transient, a linear potential sweep and a potential step technique. Four regions of the surface oxide reduction were distinguished in the galvanostatic E?t curve and four corresponding cathodic current peaks were observed in the potentiodynamic i?E profile. These four regions or peaks are attributed to the reduction of four O-containing layers: an oxygen monolayer adsorbed on the oxide surface, two oxide layers in a first and a second lattice and a multilayer oxide in the deeper lattices having a phase property. The reduction rate of the first lattice oxide layer is determined by a second electron transfer. Under a rapid stripping condition, the reduction of the second oxide layer is considered to be controlled by the place exchange reaction. The extremely large reduction rate of the multilayer oxide compared with the formation rate is explained in terms of the proton-electron model.  相似文献   

14.
Effect of the dispersity of aluminum oxide on the microhardness, wear, internal stresses, and porosity of nickel-cobalt-aluminum oxide composite electrolytic coatings deposited from a chloride electrolyte and the dependence of the content of aluminum oxide in the coating on the agitation rate and working duration of the electrolyte were studied.  相似文献   

15.
以氧化铟锡透明导电膜玻璃(ITO)做载体,先在室温下采用浸渍-提拉法制备出ZnO纳米晶作为种子层,再结合低成本的水热生长法合成了一维有序的ZnO纳米棒阵列.结合X射线衍射(XRD)、扫描电子显微镜(SEM)和能量色散谱仪(EDS)表征,研究了前驱液浓度、溶胶陈化时间、种子层提拉次数、水热生长时间和次数等5种因素对ZnO纳米棒的结构及形貌的影响.研究结果表明, ZnO纳米棒阵列的长度和直径会随着前驱液的浓度和溶胶陈化时间以及水热生长时间的延长而增加.当前驱液浓度为0.5 mol·L-1时,陈化时间为24 h,浸渍-提拉3次,水热反应3次,每次反应时间为150 min时,可得到一维有序的ZnO纳米棒阵列.  相似文献   

16.
17.
研究吸附介质的pH值、 尿素及盐类对木质素磺酸钠(SL)在氧化铁表面吸附性能的影响规律, 结果表明, 络合能力较强的柠檬酸钠使SL的吸附量几乎减少至零, 较弱络合能力的亚硫酸钠使SL的吸附量具有一定程度的降低, 而无络合能力的硫酸钠增大了SL的吸附量. 说明SL的羧基与氧化铁之间的络合吸附驱动力对吸附起主导作用, 磺酸基对其在氧化铁上吸附的影响很弱. 采用氯化锂屏蔽部分羧基后SL在氧化铁上的吸附量也有所降低, 进一步证明了羧基与氧化铁表面的络合作用是其吸附的主要驱动力.  相似文献   

18.
《Mendeleev Communications》2021,31(5):718-720
This communication describes a new method for immobilizing indium oxide nanoparticles (∼20 nm) on the surface of reduced graphene oxide. Dispersion of graphene oxide with added In2O3 nanoparticles was treated in supercritical isopropanol, both a reducing agent of graphene oxide and a reaction medium. The resulting nanocomposite was characterized by different methods of physical and chemical analysis.  相似文献   

19.
Multilayer oxide films were grown on silver in base by repetitive potential cycling; however, the type of oxide obtained, as assessed on the basis of its reduction behaviour, was dependent on the lower limit of the oxide growth cycles. Using limits of 1.03–2.60 V (RHE) the oxide film produced was assumed to be predominantly Ag2O; reduction of the latter yielded a cathodic peak at ca. 0.8 V and a surface layer of silver microparticles of diameter ranging from ca. 100 to 227 nm which, although relatively stable, were prone to rapid, extensive reoxidation. Altering the oxide growth limits to 0.7–2.60 V resulted in the growth of a different type of oxide deposit which is assumed to be AgOH; reduction of the latter occurred in a negative sweep in a random manner, i.e. in the form of cathodic spikes extending to potentials as low as ca. –0.5 V. Both types of silver oxide species are assumed to be involved in premonolayer oxidation and electrocatalysis at silver in base and the nature of the former process is discussed in some detail. Electronic Publication  相似文献   

20.
Specific light rotation (α) by solutions of propylene oxide and polypropylene oxide shows a complex dependence on medium properties. For propylene oxide, α values depend on medium basicity and polarizability, which increase α, and the ability to electrophilic solvation, which decreases α. With polypropylene oxide, α values are only determined by solvent polarizability.  相似文献   

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