共查询到20条相似文献,搜索用时 15 毫秒
1.
Nikola Drenchev Tony Spassov Ivan Kanazirski 《Journal of Applied Electrochemistry》2008,38(2):197-202
The electrochemical hydriding/dehydriding under galvanostatic conditions of nanostructured Mg2-x
Sn
x
Ni (x = 0,0.1,0.3) were studied at different temperatures in the range 28–45 °C. The discharge capacity, cycle life and electrochemical
impedance of the alloys were found to depend on the presence of Sn. Tin decreases the maximum electrochemical capacity, but
essentially improves the cycle life of Mg2Ni. Intensive corrosion of surface Mg was found to take place during the first 2–3 charge/discharge cycles to a much larger
extent for Mg2Ni, compared to the tin containing alloys. Sn decreases the electron density around the Mg atoms and therefore impedes magnesium
oxidation. It was also found that Sn hampers charge transfer but reduces the hydrogen diffusion resistance in Mg2Ni based alloys. 相似文献
2.
Ji Won Park Se Min Park Young San Yoo Hyun-Sik Han Gon Seo 《Korean Journal of Chemical Engineering》2008,25(2):239-244
The deactivation of a barium oxide-based NO
x
storage and reduction (NSR) catalyst with hydrothermal treatment was studied by treating it with 10 vol% water vapor diluted
in nitrogen at 850°C. XRD, XPS, SEM, IR of CO adsorption, and the N2 adsorption was used to investigate the physical and chemical changes of the NSR catalyst caused by the hydrothermal treatment.
The 12 h hydrothermal treatment decreased its NO2 storage capacity by 20%. However, the hydrothermal treatment significantly decreased its ability to reduce the stored NO2. The formation of an inactive phase consisting of platinum and aluminum is believed to be the cause of the severe deactivation
of the NSR catalyst. 相似文献
3.
Additives, without noble metals, based in Ce–Al mixed oxides supported on γ-alumina have been investigated as potential catalysts
for the NO
x
reduction in the FCCU regenerator. The best results were obtained with clusters of Sn–Cu–Al–O interacting with Ce–Al mixed
oxides highly dispersed on the γ-Al2O3. The strong interaction between the two complex oxides provides a stable catalyst with high activity at high temperature.
These additives would be active in the dense phase of the FCC regenerator, being deactivated at oxygen concentrations higher
than 2%, but they would be regenerated in the FCC reactor.
A. Uzcátegui is in leave to Laboratorio de cinética y catálisis del Departamento de Química, Facultad de Ciencias, Universidad
de los Andes, La Hechicera, Merida, Venezuela. 相似文献
4.
Penghua Qiu Shaohua Wu Shaozeng Sun Hui Liu Longbin Yang Guozhong Wang 《Korean Journal of Chemical Engineering》2007,24(4):683-687
This research conducts a series of industrial tests on coal reburning of a 600 MW pulverized coal boiler firing lignite, which
is one part of a coal reburning demonstration project. When running steadily under 600 MW load, the boiler has an average
NO
x
emission of 274 mg/m3 (O2 content in flue gas is converted to 6%), the NO
x
emission is reduced by 65.36%. In the meanwhile, loss of ignition (LOI) under coal reburning rarely increases. Three operation
conditions — traditional air feeding, air staging and coal reburning — are realized, respectively, during the industrial tests,
and the results indicate that coal reburning has the lowest NO
x
emission, while the traditional air feeding has the highest NO
x
emission. Under the test conditions, the higher the proportion of the reburning coal, the higher the NO
x
control can reach.
This work was presented at the 6
th
Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006. 相似文献
5.
Flavio H. Oliveira Marly E. Osugi Fabiana M. M. Paschoal Demetrius Profeti Paulo Olivi Maria Valnice Boldrin Zanoni 《Journal of Applied Electrochemistry》2007,37(5):583-592
The generation of active chlorine on Ti/Sn(1−x)Ir
x
O2 anodes, with different compositions of Ir (x = 0.01, 0.05, 0.10 and 0.30 ), was investigated by controlled current density electrolysis. Using a low concentration of
chloride ions (0.05 mol L−1) and a low current density (5 mA cm−2) it was possible to produce up to 60 mg L−1 of active chlorine on a Ti/Sn0.99Ir0.01O2 anode. The feasibility of the discoloration of a textile acid azo dye, acid red 29 dye (C.I. 16570), was also investigated
with in situ electrogenerated active chlorine on Ti/Sn(1−x)Ir
x
O2 anodes. The best conditions for 100% discoloration and maximum degradation (70% TOC reduction) were found to be: NaCl pH 4,
25 mA cm−2 and 6 h of electrolysis. It is suggested that active chlorine generation and/or powerful oxidants such as chlorine radicals
and hydroxyl radicals are responsible for promoting faster dye degradation. Rate constants calculated from color decay versus
time reveal a zero order reaction at dye concentrations up to 1.0 × 10−4 mol L−1. Effects of other electrolytes, dye concentration and applied density currents also have been investigated and are discussed. 相似文献
6.
The effect of replacing lanthanum with praseodymium on the crystal chemistry parameters of solid solutions of La1 − x
Pr
x
BaCuFeO5 + δ has been investigated using X-ray powder diffraction analysis and IR spectroscopy. The thermal expansion, electroconductivity,
and thermopower of these phases have been studied in air in the temperature range 300–1100 K. The values of linear thermal
expansion coefficients (LTEC) of ceramics in different temperature ranges have been determined, and the values of electric
transfer parameters in the above oxides have been calculated. It has been established that replacing lanthanum with praseodymium
resulted in the compression of the elementary oxide unit La1 − x
Pr
x
BaCuFeO5 + δ, decrease in the content of labile oxygen in them (δ), decrease in nonmonotonic electroconductivity, increase in thermopower,
decrease in LTEC, and difficulties in charge transfer in these phases. 相似文献
7.
D. Profeti K. Servat F. Hahn K. B. Kokoh P. Olivi 《Journal of Applied Electrochemistry》2008,38(6):837-843
The electrochemical oxidation of ethanol at Sn(1−x)Ir
x
O2 electrodes (with x = 0.01, 0.05, 0.1 and 0.3) was studied in 0.1 mol L−1 HClO4 solution. Electrolysis experiments were carried out and the reaction products were analyzed by Liquid Chromatography. It
was found that the amounts of the reaction products depended on the composition of the electrode. In situ infrared reflectance
spectroscopy measurements were performed to identify the adsorbed intermediates and to postulate a reaction mechanism for
ethanol electrooxidation on these electrode materials. As evidence, acetaldehyde and acetic acid were formed through a successive
reaction process. Carbon dioxide was also identified as the end product, showing that the cleavage of the carbon–carbon bond
occurred. These results indicate that the synthesized catalysts are able to lead to the total combustion of organic compounds.
Analysis of the water bending band at different potentials illustrated its role at the electrode interface. 相似文献
8.
Hui-Chao Chen Chang-Sui Zhao Yong-wang Li Duan-Feng Lu 《Korean Journal of Chemical Engineering》2007,24(5):906-910
An incineration test of a toxic chemical organic waste liquid was conducted on a circulating fluidized bed (CFB) incinerator.
The flue gas was measured online with the advanced SAE-19 flue gas analyzer. The effects of several factors, in terms of flow
rate of waste liquid, ratio of waste liquid injected into dense bed of the CFB, excess air coefficient, the secondary air
fraction and bed temperature on NO
x
emissions, were verified. The experimental results show that NO emissions in flue gas increase with increase in the flow
rate of the waste liquid injected into the bed or the excess air coefficient or the bed temperature and those decrease with
increase in the ratio of waste liquid injected into the dense bed of the CFB or the secondary air fraction. During the test
runs, NO
x
concentration in flue gas met the national regulation on NO
x
emissions due to suppressive effect of low temperature and staged combustion in CFB on NO
x
formation.
This paper was presented at the 6
th
Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006. 相似文献
9.
Synthesized silicas modified with alumina, titania, and zirconia (about 13% wt) were used as supports for dispersing nanosized CuO phase. All the prepared catalysts, containing about 1 mmolcu gcat
-1 possessed high surface areas (230–430 m2gcat
-1) and homogeneous coverage of the relevant support, as revealed by SEM-EDS analysis. The nature of the support and its acidity directed the CuO deposition modifying the dimensions of the CuO aggregates and the ratio between highly and scarcely interacting copper species with support, as revealed by complementary analyses. The redox character of the CuO phase was studied realizing cycles of programmed temperature reduction/oxidation (TPR-TPO) which gave the extent of CuO reduction and CuO re-oxidation. Deconvolution of the reduction profiles permitted identifying different copper species which presence depended on the support nature. Attempts were made to individuate relations between the properties of the CuO species and catalytic activity in NO
x
reduction with ethene (HC-SCR process) in highly oxidant atmosphere. The CuO phase deposited on the most acidic supports showed the best activity and selectivity in the NO
x
reduction. 相似文献
10.
A major issue when using selective catalytic reduction (SCR) De-NO x catalysts is the risk of physical deactivation due to particle deposition and plugging of the monolithic catalysts. In the present study, numerical computations were carried out to investigate the particle deposition behaviors in monolithic SCR catalysts. Based on the calculation results, the effects of particle diameter, particle density, gas velocity, turbulent intensity, chemical reaction and channel size on particle deposition were analyzed in detail. Increasing gas velocity and equivalent diameter of channel can mitigate particle deposition. The increases of turbulent intensity and channel length both lead to the rise of particle deposition ratio. For particles with high Stokes number, particle deposition mainly takes place in the inlet section of catalysts. For particles with low Stokes number, sediment can be observed in the middle and outlet sections of catalysts. De-NO x chemical reaction can mitigate particle deposition, but the effect of chemical reaction on particle deposition is inactive. 相似文献
11.
The structure of glasses in the x(0.16GaCh2 · 0.84GeCh2) · (1 − x)(SbCh1.5) (Ch = S, Se) system has been investigated using Raman scattering. The structure of glasses is interpreted as a superposition
of the following structural units: Ge(Ga)Ch4/2, Ch3/2Ge(Ga)-Ge(Ga)Ch3/2, SbCh3/2, and -Ch-Ch-, where Ch = S and Se. The change in the fraction of the corresponding structural units with a change in the
glass composition has been analyzed. 相似文献
12.
Jun Li Xianyou Wang Qinghua Huang Chunling Dai Sergio Gamboa P. J. Sebastian 《Journal of Applied Electrochemistry》2007,37(10):1129-1135
A series of RuO2 · xH2O/carbon aerogel (CA) composite electrode materials was prepared by a chemical precipitation method. Ultrasonication was used
to accelerate the chemical reaction and improve the dispersion of RuO2 · xH2O particles on the surface and the pores of the aerogel. The structure and morphology of the as-prepared composite were characterized
by N2 adsorption isotherm, X-ray diffraction (XRD), and field emission-scanning electron microscopy (FE-SEM). The results showed
that the CA had a pearly network structure and the composites had a relatively high specific surface area and mesopore volume.
The electrochemical performance of the composite electrodes was studied by cyclic voltammetry, galvanostatic charge/discharge
measurements and electrochemical impedance measurements. The results indicated a substantial increase in the specific capacitance
of the composite. Moreover, the utilization efficiency of RuO2 · xH2O was greatly improved by loading it on the conductive and porous CA due to a significant improvement in the inter-particle
electronic conductivity and the extensive mesoporous network of the composites. 相似文献
13.
Aliou Faye Saidou Sall Jean-Luc Chotte Didier Lesueur 《Nutrient Cycling in Agroecosystems》2007,79(1):35-44
Acacia nilotica var. tomentosa trees from the Diarra protected forest located in the Senegal River valley were identified for the assessment of both biological
nitrogen fixation, using the natural abundance method, and soil bio-functioning parameters (nodulation, root biomass, total
microbial biomass, and potential N mineralization). The presence and the genetic diversity of indigenous rhizobia nodulating
A. nilotica var. tomentosa was also investigated, taking into account distance from the trunk (0, 1, 2, and 3 m) and depth (0–25, 25–50, and 50–75 cm).
Surprisingly, no nodules on the trees root systems were found, whereas under laboratory conditions the presence of indigenous
rhizobia nodulating A. nilotica var. tomentosa was demonstrated in the analyzed soils (90% of the nodules harvested on the trapped plants were occupied by the same Inter-Genic
Spacer (IGS) group, IGS1). There was no significant influence of trees and/or depth on total microbial biomass and potentials
of nitrogen mineralization. Some assumptions were formulated on the possible combined effect of flooding, which usually occurs
annually during 4–7 months, and the clayey soils in the Diara forests. Although a deeply natural nodulation of A. nilotica var. tomentosa trees by indigenous rhizobia is not excluded, but it still remains to be demonstrated. 相似文献
14.
The catalytic activity of sulfated titania (ST) calcined at a variety of temperatures has been investigated for selective catalytic reduction (SCR) of NO by NH3. The NO removal activity of ST catalyst mainly depends on its sulfur content, indicating critical role of sulfur species on the surface of TiO2. The role of sulfur is mainly the formation of acid sites on the catalyst surface. The presence of both BrØnsted and Lewis acid sites on the surface of sulfated titania has been identified by IR study with the adsorption of NH3 and pyridine on ST. The reduction of the intensity of IR bands representing BrØsted acid sites is more pronounced than that revealing Lewis acid sites as the calcination temperature increases. It has been further clarified by IR study of ST500 catalyst evacuated at a variety of temperatures. The NO removal activity also decreases with the increase of the catalyst calcination temperature. It simply reveals that BrØnsted acid sites induced by sulfate on the catalyst surface are primarily responsible for the enhancement of catalytic activity of ST catalyst containing sulfur for NO reduction by NH3. 相似文献
15.
Jung-Hyun Park Hyeryeung Noh Tae-Sun Chang Chae-Ho Shin 《Korean Journal of Chemical Engineering》2018,35(3):645-653
We prepared 0.1Al-0.9Ce supports using various precipitants such as NH4OH, KOH, NaOH, K2CO3, and Na2CO3 to prepare Pt-based CO oxidation catalysts. Of the studied catalysts, the Pt/0.1Al-0.9Ce_NH4OH catalyst showed the optimum activity for CO oxidation. Catalysts prepared with carbonate-form precipitants revealed relatively lower activity than carbonate-free precipitants. A temperature at 50% CO conversion of all samples was observed in the low-temperature region in the presence of water vapor because of the promotional effect of the water-gas shift reaction. Several characterization results revealed that catalytic activity was related to oxygen capacity and Pt dispersion was attributable to precipitant nature. 相似文献
16.
Mónica A. Pérez Carlos J. Caro Rodrigo A. Cancino Franco M. Rabagliati 《Polymer Bulletin》2003,51(3):199-208
Summary
The homo- and copolymerization of styrene (S) with
p-methylstyrene (p-MeS) and p-tert-butylstyrene
(p-ButS) has been tested using
initiator systems of the
Ph2Zn-metallocene-MAO type. The
metallocenes used were CpTiCl3,
IndTiCI3,
(n-BuCp)2TiCl2,
Ind2ZrCl2 and
Et(Ind)2ZrCl2. The
Ph2Zn-metallocene-MAO systems
homopolymerize styrene, p-methylstyrene and p-tert-butylstyrene,
producing syndiotactic polymers in the case of the titanocenes
and amorphous polymers in the case of the zirconocenes. The
S/p-MeS and S/p-ButS copolymers
obtained with the Ph2Zn-titanocene-MAO
systems are enriched in the comonomer with respect to the
initial feed. 相似文献
17.
Gökhan Demirel 《Journal of Polymer Research》2007,14(1):23-30
In the present study, a series of ionic poly(N-t-butylacrylamide-co-acrylamide) [P(NTBA-co-AAm)] hydrogels were synthesized by free-radical crosslinking copolymerization
of N-t-butylacrylamide (NTBA) and acrylamide (AAm) monomers in fixed amount, but changing amount of maleic acid (MA) comonomer in
methanol using N,N-methylene-bis-acrylamide (BAAm) as the crosslinker, ammonium persulfate (APS) as the initiator, and N,N,N′,N′-tetramethylethylenediamine (TEMED) as the activator. The swelling behavior of these hydrogels was analyzed in buffer solutions
at various pHs. The prepared hydrogels also were investigated swelling-deswelling transition in water depending on the temperature.
For the bovine serum albumin (BSA) adsorption, the effect of pH, temperature, initial protein concentration and adsorption
rate were investigated. Maximum BSA adsorption was observed at pH 5.0 which is close to the isoelectric pH of BSA (pH 4.8).
The highest adsorption rate was achieved in about 12 h. and also, maximum BSA adsorption was found at +5°C. 相似文献
18.
Selective hydrogenation of trans-cinnamaldehyde was studied on SiO2-supported Co–Ir bimetallic catalysts. Addition of Ir to Co/SiO2 increased the hydrogenation selectivity and activity of cinnamaldehyde to the corresponding cinnamyl alcohol (UOL). A selectivity as higher as 93% to UOL at ambient temperature under H2 pressure of 2.0 MPa was obtained over catalyst with loadings of 10 wt% Co and 0.5 wt% Ir (Co10.0Ir0.5/SiO2). The XRD, Raman and TPR results showed that the higher dispersed Co3O4 particles were formed on SiO2 due to the addition of Ir, which increased the reducibility of Co3O4 to Co0. The reduction of oxidized Co–Ir/SiO2 samples occurred at the temperatures with about 200 K lower than that of the one without Ir species as evidenced by the observations of TPR and in-situ Raman characterizations. The XPS results indicated that the large parts of Co3O4 in the sample of Co–Ir/SiO2 were reduced to Co0, but only small parts of that were reduced to Co0 in the sample of Co/SiO2 under flowing 5%H2/Ar at 673 K. The CO chemisorptions revealed that the irreversible uptakes of CO on the reduced Co–Ir/SiO2 sample was much higher than those on the reduced Co/SiO2 and Ir/SiO2, and also higher than the combination of that on the reduced Co/SiO2 and Ir/SiO2, respectively. The experimental data suggested that the presence of Ir played a key role in the reduction of Co3O4 to Co0 through a strong interaction between them and that the amount of Co0 at the catalyst surfaces was correlated to the activity and more importantly to the UOL selectivity. 相似文献
19.
M. R. Ganjali P. Norouzi F. Faridbod S. Riahi M. R. Yaftian A. Zamani D. Matt 《Journal of Applied Electrochemistry》2007,37(7):827-833
A Th4+ ion-selective membrane sensor was fabricated from poly (vinyl chloride) (PVC) matrix membrane containing 2-(diphenylphosphorothioyl)-N′,N′-diphenyl acetamide (DPTD) as a neutral carrier, potassium tetrakis (p-chlorophenyl) borate (KTpClPB) as anionic excluder and o-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The effects of the membrane composition, pH and additive
anionic influence on the response properties were investigated. The sensor, comprising 30% PVC, 63% solvent mediator, 4% ionophore
and 3% anionic additive demonstrates the best potentiometric response characteristics. It displays Nernstian behavior (15.2 ± 0.5 mV
per decade) over the concentration range 1.0 × 10−2–1.0 × 10−6 M. The detection limit of the electrode is 6.3 × 10−7 M (∼140 ng/ml). The response time of the electrode is 30 s .The sensor can be used in the pH range 3.0–9.0 for about 6 weeks.
The membrane sensor was used as an indicator electrode in the potentiometric titration of Th4+ ions with EDTA. It was successfully applied to the determination of thorium ions in binary mixture. 相似文献
20.
György Szőllősi 《Catalysis Letters》2012,142(3):345-351