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131.
采用共价接枝法, 以氨丙基-三乙氧基硅烷为氨源, 制备了一系列的NH2-SBA-15催化剂, 通过微量吸附量热技术定量地分析了该催化剂表面碱性中心的强度、数量和分布状态. 实验结果表明, SBA-15在 550 ℃焙烧6 h, 氨基硅源与SBA-15质量比为1.5, 是合成NH2-SBA-15催化剂最适宜的条件. 运用微量吸附量热技术实现了对NH2-SBA-15催化剂合成条件的优化. 相似文献
132.
A.D. Drozdov 《European Polymer Journal》2007,43(5):1681-1690
A model is developed for thermal degradation of polymer nanocomposites. A composite is thought of as an equivalent network of linear chains with attached side-groups. Thermal degradation is treated as combination of (i) binary scission (fragmentation) of backbone chains, and (ii) detachment of side-groups and their subsequent annihilation (diffusion to the surface of a sample and desorption). An explicit solution is derived for the kinetic equation. This solution involves three adjustable parameters that are found by fitting observations on isotactic polypropylene reinforced with carbon nanofibres. Good agreement is demonstrated between the experimental data and the results of numerical simulation. 相似文献
133.
高负载率纳米Pt-Ru/C催化剂的制备和表征 总被引:2,自引:0,他引:2
以Vulcan XC-72R碳黑为载体, 通过在含十二烷基硫酸钠(SDS)的乙二醇溶液中直接还原氯铂酸和三氯化钌, 制备了负载率为60%的纳米PtRu/C催化剂. 透射电镜(TEM)和X射线衍射(XRD)分析结果表明, SDS的加入可显著改善PtRu纳米颗粒在载体表面分散性, 平均粒径达到2.7 nm. 电化学循环伏安法(CV)测试的结果显示, 利用这种方法制备的纳米PtRu/C催化剂对于甲醇氧化具有较强的抗中毒能力和较高的电催化活性. 相似文献
134.
Izaskun Bustero García Ainara Obieta Isabel Muñoz Roberto Rincón Inés Arteche Amaya 《Mikrochimica acta》2006,152(3-4):239-247
Interest in carbon nanotubes (CNT) has grown at a very rapid rate in the last decade. Their interesting physical and chemical
properties open attractive possibilities in many application areas. These properties depend on the process conditions during
synthesis and on subsequent purification steps. Recent studies have demonstrated that CNT can promote the electron transfer
of biomolecules. These exceptional properties make them attractive for use in electrochemical biosensors.
Multi walled nanotubes have been synthesized by the Chemical Vapor Deposition (CVD) method using methane as a carbon source
and Ni–Al2O3–SiO2 as the catalyst. The influence of the variation of certain reaction parameters such as feed gas composition, catalyst mass,
temperature and reaction time in the yield of the CVD process has been established. In addition, the structural and chemical
characteristics of the CNTs have been studied and a purification process to eliminate the catalyst and amorphous carbon has
been developed that involves a gaseous oxidative process and acid treatment. The efficiency of the purification step has been
determined by analytical techniques.
Atomic force microscopy, Raman scattering, thermogravimetric analysis, inductively coupled plasma atomic spectroscopy are
the characterization techniques employed in this work. 相似文献
135.
A room temperature ionic liquid N‐butylpyridinium hexafluorophosphate (BPPF6) was used as a binder to make an ionic liquid modified carbon paste electrode (IL‐CPE), which showed good characteristics such as simple preparation procedure, fast electrochemical response and good conductivity. The electrochemical oxidation of ascorbic acid (AA) on the new IL‐CPE was carefully studied. The oxidation peak potential of AA on the IL‐CPE appeared at 109 mV (vs. SCE), which was about 338 mV decrease of the overpotential compared to that obtained on the traditional carbon paste electrode (CPE) and the oxidation peak current was increased for about four times. The electrochemical parameters of AA on the IL‐CPE were calculated with the charge transfer coefficient (α) and the electrode reaction rate constant (ks) as 0.87 and 0.800 s?1, respectively. Based on the relationship of the oxidation peak current and the concentration of AA a sensitive analytical method was established with cyclic voltammetry. The linear range for AA determination was in the range from 1.0×10?5 to 3.0×10?3 mol/L with the linear regression equation as Ip (μA)=?2.52–0.064C (μmol/L) (n=13, γ=0.9942) and the detection limit was calculated as 8.0×10?6 mol/L (3σ). The proposed method was free of the interferences of coexisting substances such as dopamine (DA) and amino acids etc., and successfully applied to the vitamin C tablets determination. 相似文献
136.
《Electroanalysis》2004,16(17):1451-1458
A new carbon electrode material, obtained by mixing single wall carbon nanotubes (SWNTs) with a mineral oil binder is studied. Carbon nanotube pastes show the special properties of carbon nanotubes combined with the various advantages of composite electrodes such as a very low capacitance (background current) and the possibility of an easy preparation, modification and renewal. A better knowledge of the characteristics of electrode reactions at carbon nanotube paste (CNTP) electrodes was obtained studying the electron transfer rates of various redox couples under different pretreatment conditions. A critical comparison with carbon paste (CP), platinum (Pt) and glassy carbon (GC) electrodes was also carried out. Capacitance and resistance values were also calculated for all electrodes investigated. Both untreated and treated CNTP electrodes showed a low resistance while the capacitance was markedly reduced with CNTP electrodes previously treated with concentrated nitric acid. An electrochemical pretreatment on CNTP electrodes was developed which showed an excellent result towards two‐electron quinonic structure species. After this treatment the heterogeneous standard rate constants for p‐methylaminophenol sulfate (MAP) and dopamine resulted to be significantly higher (2.1×10?2 cm/s and 2.0×10?2 cm/s, respectively) than those obtained with the other electrodes studied. Reproducibility, stability and storage characteristics of CNTP electrodes were also reported. 相似文献
137.
Thermodynamic and kinetic parameters have been established for the reaction between the carbon acid, 4-nitrophenylnitromethane,
(4-NPNM), and the base N’-n-propyl-N,N-di-n-propylbenzimidamide, (N’PDPBA), in mesitylene and in chlorobenzene. In some cases deuteron transfer from 4-(D2)NPNM to the base has also been studied. In addition, some results for the proton transfer reaction in tetrahydrofuran have
been collected. Spectrophotometric methods have been employed to monitor the ion-pair product, which is solvatochromic. In
general the solvent dependence of the parameters is as expected, but there is some indication of specific solvation. The kinetic
isotope effects of 11 and 8 in mesitylene and chlorobenzene, respectively, are larger than those predicted classically. However,
as is discussed the n-propyl group on the secondary nitrogen of the base may serve to reduce the extent of tunneling compared
to that in an unsubstituted analogue by a steric effect. 相似文献
138.
Carbon nanotubes used for constructing biosensor was described for the first time. Single-wall carbon nanotubes (SWNTs) functionalized with carboxylic acid groups were used to immobilize glucose oxidase forming a glucose biosensor. The biosensor response can be determined by amperometric method at a low applied potential (0.40V). 相似文献
139.
Mo、W金属氧化物对CH4/CO2重整Ni基催化剂性能的影响 总被引:2,自引:0,他引:2
用XRD、XPS、元素分析、TEM和活性评价等方法研究过渡金属氧化物MoO3和WO3对SiO2负载的Ni基催化剂物理化学性质和CH4/CO2重整制合成气催化性能的影响.结果表明,在负载型的镍催化剂中,MoO3和WO3的添加一方面提高了Ni的核外电子密度,减弱了对CH4深度裂解积炭;另一方面使催化剂表面镍的相对浓度降低,结构上起到了隔离、分散金属颗粒的作用,氧的相对浓度升高,有效提高了催化剂的抗烧结和抗积炭能力,显示出较好的催化稳定性. 相似文献
140.
Y. BallesterosM.J. Gonzalez de la Huebra M.C. QuintanaP. Hernandez L. Hernandez 《Microchemical Journal》2003,74(2):193-202
The electrochemical behaviour of kinetin (6-furfurylaminopurine) on a carbon paste modified with OV-17 silicone electrode, is studied. The determination of kinetin is possible working in square wave voltammetric techniques, reaching limits of determination of 38.7 ng ml−1. The proposed method was successfully applied to determine the cytokinin in extracts of apples (previously spiked with kinetin) and the obtained results were in accordance with the results obtained with HPLC-UV. 相似文献