Structural and electrical changes in NdSrNiO4−δ by substitute nickel with copper

A novel series of the formula NdSrNi_1−xCu_xO_4−δ were synthesized for various values of x ranging from 0 to 1 in 1 atm of O₂ gas flow using conventional solid-state methods and were characterized by powder X-ray diffraction and electrical resistivity measurements. The compounds have been shown to adopt the K₂NiF₄-type structure. The oxygen stoichiometry of the compounds was determined from thermo-gravimetric analysis (TGA). An analysis of the micro-structure of the neodymium strontium nickel copper oxide is described. All the samples were semi-conducting from room temperature down to 77 K. The effect of Cu²⁺ incorporation on the structural and electrical properties of NdSrNi_1−xCu_xO_4−δ, 0?x?1, are discussed in terms of Jahn-Teller distortion of the (Ni/Cu)O₆ octahedra and mixed valence character of copper.     

便携式微波等离子体离子化检测器气相色谱仪用于气体分析的研究

本文使用自制的便携式微波诱导等离子体离子化检测器气相色谱仪对可燃气体中N_2、O_2、H_2和CH_4的测定方法进行了研究。以氩气为载气和工作气体,考察了改进后的微波诱导等离子体离子化检洲器(MIPID)的工作参数对测定的影响。对煤气和乙炔中的O_2、N_2、H_2和CH_4进行了测定,分析结果与热导池检测器(TCD)的气相色谱法一致。讨论了高电离电位(>11.7ev)气体组分在MIPID中响应特性。     

Characterization and separation of Al13 species using gel-filtration chromatography

A polyaluminum chloride (PAC) sample was prepared using a slow alkaline titration method. The Bio-Gel P-100 gel column chromatographic technique was used to separate and characterize the various forms of aluminum present in the prepared PAC solution. The effluents from a gel column were monitored using online chemical method: Al-Ferron timed complexation spectrophotometry and by ²⁷Al nuclear magnetic resonance (NMR) spectroscopy. Effects of different experimental conditions such as eluent flow rate, ionic strength and pH on separation of Al₁₃ were investigated. Experimental results indicated that molecule size exclusion was not the only parameter affecting the column chromatographic separation efficiency of Al₁₃ but molecule charge as well. Reducing the eluent flow rate, increasing the ionic strength and suitable pH resulted in increase in the separation efficiency. Experimental results clearly indicated that by varying the experimental conditions, it is possible to produce pure Al₁₃ species using a gel column chromatographic technique.     

掺杂ZrO＿2的Pt／Al＿2O＿3表面氧性质及一氧化碳氧化性能研究

用ＴＰＤ－ＭＳ、ＴＰＳＲ－ＭＳ及ＣＯ氧化活性测定等方法研究了Ｐｔ／Ａｌ２Ｏ３和掺杂超细ＺｒＯ２的样品的表面氧脱出－恢复性能、ＣＯ表面氧化性能及催化氧化性能．结果表明，在Ｐｔ／Ａｌ２Ｏ３中掺杂ＺｒＯ２后，样品表面上的氧物种脱出和氧化恢复性能明显提高，脱氧量也明显增大；并发现在ＣＯ－ＴＰＳＲ过程中程脱物ＣＯ２的脱附量大小及峰顶温度次序与对ＣＯ的催化氧化活性也有一致的关系     

BaF2/La2O3催化剂上甲烷氧化偶联反应活性氧物种的原位红外光谱

用原位红外光谱研究了BaF2/La2O3催化剂上甲烷氧化偶联反应的活性氧物种.结果表明,催化剂经O2预吸附后,在1 108~1 118 cm-1处出现超氧物种O2-的O-O键伸缩振动峰.经18O2同位素交换实验后,原1 108~1 118 cm-1处谱峰的强度减弱,同时在1 086和1 051 cm-1处出现(O18O)-物种和18O2-物种的吸收峰.同位素交换实验进一步确证了1 108~1 118cm-1处谱峰确为O2-物种的吸收峰.在700℃下,O2-物种能够活化CH4生成C2H4,而且O2-物种的消耗量和C2H4的生成量呈很好的消长对应关系.超氧物种O2-是BaF2/La2O3催化剂上甲烷氧化偶联反应的活性氧物种.     

Plasma-Catalytic Decomposition of Phenols in Atmospheric Pressure Dielectric Barrier Discharge

This study investigated the processes for the destruction of phenol and its derivatives (resorcin and pyrocatechol) in aqueous solutions under the action of an oxygen dielectric barrier discharge (DBD) at atmospheric pressure in the presence or absence of catalysts in the plasma zone. It was shown that the DBD had a high decomposition efficiency for phenol and its derivatives (up to 99%). Phenol was the most stable and pyrocatechol was the least. In a plasma-catalytic hybrid process, the effective rate constants for phenol, resorcin and pyrocatechol decomposition were 11, 4 and 2.5 times higher, respectively, than those for the DBD treatment without catalysts. The process also resulted in a 1.4, 1.6 and 1.2 times higher rate of carboxylic acid formation for phenol, resorcin and pyrocatechol, respectively. The fractional conversion into the respective carboxylic acids reached 56% for phenol and 68% for resorcin and pyrocatechol.     

原位漫反射红外光谱法研究SO2对Ag/Al2O3选择性催化丙烯还原NOx反应的影响

 以Ag/Al2O3为催化剂,采用原位漫反射傅里叶变换红外光谱法研究了SO2对C3H6选择性还原NOx反应的影响. 结果表明, SO2在催化剂表面转化为硫酸盐,并且随着硫酸盐累积量的增加,其主要红外特征吸收峰由低波数向高波数漂移. 高浓度表面硫酸盐的存在不仅抑制了催化剂表面硝酸盐的生成,而且抑制了硝酸盐与表面烯醇式物种(RCH=CH-O-)或乙酸盐物种进一步反应,生成活泼的反应中间体异氰酸酯(-NCO), 这是导致Ag/Al2O3催化剂上C3H6选择性还原NOx活性降低的主要原因.     

Oxygen diffusion in SrCe<Subscript>0.95</Subscript>Yb<Subscript>0.05</Subscript>O<Subscript>3−δ</Subscript>

¹⁸O/¹⁶O isotope exchange depth profiling (IEDP) combined with secondary ion mass spectrometry (SIMS) has been used to measure the oxygen tracer diffusivity of SrCe_0.95Yb_0.05O_3– between 800 °C and 500 °C at a nominal pressure of 200 mbar. The values of D* (oxygen tracer diffusion coefficient) and k (surface exchange coefficient) increase steadily with increasing temperature, and the activation energies are 1.13 eV and 0.96 eV, respectively. Oxygen ion conductivities have been calculated using the Nernst–Einstein equation. The transport number for oxide ions at 769 °C, the highest temperature studied, is only ~0.05. Moreover, SrCe_0.95Yb_0.05O_3– has been studied using impedance spectroscopy under dry O₂, wet O₂ and wet H₂ (N₂/10% H₂) atmospheres, over the range 850–300 °C. Above ~550 °C, SrCe_0.95Yb_0.05O_3– shows higher conductivity in dry O₂ than in wet O₂ or wet H₂; below that temperature the results obtained for the three atmospheres are comparable. Dry O₂ shows the highest activation energy (0.77 eV); the activation energies for wet O₂ and wet H₂ are identical (0.62 eV).Abbreviations HTPC high-temperature proton conductor - IEDP isotope exchange depth profiling - SIMS secondary ion mass spectrometryPresented at the OSSEP Workshop Ionic and Mixed Conductors: Methods and Processes, Aveiro, Portugal, 10–12 April 2003     

Irreversible and Reversible Deactivation of Bilirubin Oxidase by Urate

Oxygen is electroreduced to water on a carbon cathode coated with wired bilirubin oxidase in a pH 7.4 0.15 M NaCl phosphate buffer solution at 37 °C at much lesser polarization than it is on a pure platinum cathode in 0.5 M H₂SO₄. While the wired bilirubin oxidase cathode operates for over a week in the aerated or oxygenated buffer solution, it is degraded rapidly when in serum. We reported earlier that in the presence of O₂ an intermediate product of the electrooxidation of urate, which is a normal serum component, irreversibly damages the wired bilirubin oxidase and also reported that the electrocatalyst is irreversibly damaged, in the absence of urate, when it is brought, by disconnecting the electrode, to the O₂/H₂O half cell potential at pH 7.4. Here we report that a) dissolved bilirubin oxidase is irreversibly and rapidly damaged by urate in the presence of O₂; and b) that the immobilized wired bilirubin oxidase electrocatalyst is not only irreversibly deactivated by urate in the presence of O₂ in a few hours, but is initially reversibly deactivated, in 1 min or less, by the urate in the presence of O₂.     

Cooperation of reducing species for NO reduction over Ag/Al2O3 under oxidizing conditions

Summary The cooperation effect of reducing species for selective reduction of NO over Ag/Al₂O₃ has been investigated in the presence of excess oxygen. When the combinations of propene or propane and ethanol or methanol were used as reducing agents, NO reduction took place over a wider temperature range, compared with a single hydrocarbon as reducing agent.