共查询到20条相似文献,搜索用时 31 毫秒
1.
Samantha J. Roberts Nathan G. Carr Jonathan McLaughlin Helena E. Hagelin-Weaver 《International Journal of Hydrogen Energy》2018,43(29):12970-12984
Several novel materials were synthesized by precipitating iron oxide (using the previously optimized 10% Fe loading by weight) onto mixtures of nanoparticle zirconia and ceria to investigate the effects of adding CeO2 to FeOx/ZrO2 materials in the thermochemical water splitting reaction. At water splitting temperatures of 1000 °C (after thermal reduction at 1450 °C), the stability of the CeO2-containing materials was lower than for the FeOx/ZrO2 material, and there was no advantage to adding CeO2 to the FeOx/ZrO2 material. However, when operating at a water splitting (WS) temperature of 1200 °C, the stability increased and the hydrogen production was significantly higher over most materials compared with a water splitting temperature of 1000 °C. At a WS temperature of 1200 °C the FeOx/Zr75Ce25O2 (75% Zr75O2 and 25% CeO2 by weight) and FeOx/Zr50Ce50O2 materials performed slightly better than the FeOx/ZrO2 material, and X-ray photoelectron spectroscopy data revealed that the surface concertation of iron is less important compared with water splitting at 1000 °C. The temperature programmed reduction data indicated that the FeOx-CeO2 interactions were weaker compared with FeOx-ZrO2 interactions, since the FeOx reduction occurred at lower temperatures for the CeO2-containing materials. The weaker interactions can explain why the stability was lower for the materials containing CeO2 (sintering of FeOx was likely more pronounced) The X-ray diffraction data revealed that ZrO2-CeO2 solid solutions formed after activation at 1450 °C and lattice volume calculations indicated that iron did incorporate into the ZrO2-CeO2 matrices. More incorporation was observed after water-splitting at 1200 °C compared with a lower temperature (1000 °C), and likely explains why the materials were more stable during water-splitting at 1200 °C. 相似文献
2.
We report the effects of substrate temperatures on the thermal stability of AlxOy/Pt/AlxOy multilayered selective solar absorber coating (MSSAC). The samples were deposited at different substrate temperatures (from room temperature up to 250 °C), and then annealed at various temperatures (300–600 °C) in air for 2 h. Characterizations are made via X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Atomic Force Microscopy (AFM), Raman Spectroscopy, UV–Vis and emissometeric measurements. These coatings were found to be thermally stable up to 500 °C with good spectral selectivity of 0.930/0.11. Furthermore, the observed decrease in the spectral selectivity 0.883/0.13 at 600 °C is attributed to the diffusion of Cu and the formation of CuO phase. Such phase formation was confirmed using XRD and Raman spectral analysis. The insensitiveness of the thermal stability of such coatings on the substrate temperature is demonstrated. 相似文献
3.
《International Journal of Hydrogen Energy》2020,45(16):9342-9352
Ammonia decomposition is an effective way for high purity hydrogen production, yet the increase of catalytic activity at low temperatures remains a big challenge for this process. In this paper, a CeO2–ZrO2 composite with Al as the secondary dopant was synthesized by the co-precipitation method, which was used as the carrier of nickel metal for ammonia decomposition. The experimental results showed that an obvious increase in catalytic activity of the ammonia decomposition at the relatively low temperature range of 450–550 °C was achieved over the nickel catalyst with CeO2–ZrO2 composite as the metal carrier. Specifically, the complete decomposition of ammonia was achieved at 580 °C for Ni/Al–Ce0.8Zr0.2O2 catalyst, while only 92% of ammonia was decomposed at 600 °C over the reference Ni/Al2O3 catalyst. The characterization results indicated that the introduction of Al as the secondary dopant of ceria not only increases the specific surface area and oxygen defects on the surface, but also enhances the nickel metal dispersion and metal-support interaction, thus enhances the catalytic performance of Ni/Al–Ce0.8Zr0.2O2 catalyst in the ammonia decomposition. 相似文献
4.
Xingfu Shang Digu Deng Xueguang Wang Weidong Xuan Xiujing Zou Weizhong Ding Xionggang Lu 《International Journal of Hydrogen Energy》2018,43(14):7179-7189
A series of 30 wt%Ni/CexZr1?xO2 catalysts doped with Ru ranging from 0 to 5 wt% were prepared by one-pot hydrolysis of metal nitrates with ammonium carbonate for carbon dioxide methanation at low temperature range of 150–310 °C. The influences of Ce/Zr molar ratios and Ru contents on the physicochemical properties and catalytic activities of prepared catalysts were systematically investigated. The addition Ru can improve the Ni dispersion and the basicity of the yRu-30Ni/Ce0.9Zr0.1O2 catalysts surface. As a result, their low-temperature catalytic activity had been enhanced over these doped Ru promoted catalysts. The optimal catalyst was 3Ru-30Ni/Ce0.9Zr0.1O2 on which the CO2 conversion reached theoretical equilibrium value as high as 98.2% with the methane selectivity of 100% at a reaction temperature as low as 230 °C. Moreover, there was almost no deactivation for the 3Ru-30Ni/Ce0.9Zr0.1O2 catalyst during 300 h at 230 °C indicating excellent catalytic stability and coke resistence ability. It was also found that the low-temperature activity of 3Ru-30Ni/Ce0.9Zr0.1O2 catalyst prepared by one-pot hydrolysis method was much higher than the one prepared by impregnation method. 相似文献
5.
Barbara Scherrer Antonella Rossi Julia MartynczukMarta D. Rossell Anja Bieberle-HütterJennifer L.M. Rupp Rolf ErniLudwig J. Gauckler 《Journal of power sources》2011,196(18):7372-7382
Si-diffusion from Si-based substrates into yttria-stabilized-zirconia (YSZ) thin films and its impact on their microstructure and chemistry is investigated. YSZ thin films used in electrochemical applications based on micro-electrochemical systems (MEMS) are deposited via spray pyrolysis onto silicon-based and silicon-free substrates, i.e. SixNy-coated Si wafer, SiO2 single crystals and Al2O3, sapphire. The samples are annealed at 600 °C and 1000 °C for 20 h in air. Transmission electron microscopy (TEM) showed that the SixNy-coated Si wafer is oxidized to SiOz at the interface to the YSZ thin film at temperatures as low as 600 °C. On all YSZ thin films, silica is detected by X-ray photoelectron spectroscopy (XPS). A particular large Si concentration of up to 11 at% is detected at the surface of the YSZ thin films when deposited on silicon-based substrates after annealing at 1000 °C. Their grain boundary mobility is reduced 2.5 times due to the incorporation of SiO2. YSZ films on Si-based substrates annealed at 600 °C show a grain size gradient from the interface to the surface of 3 nm to 10 nm. For these films, the silicon content is about 1.5 at% at the thin film's surface. 相似文献
6.
Kang Yuan Yueguang Yu Yan Wu Xiaojuan Ji Zhenyuan Xu Jie Shen 《International Journal of Hydrogen Energy》2018,43(28):12782-12788
In this paper, a new plasma spray technology working in low pressure condition has been successfully applied to deposit Lix(Ni,Co)yO2 catalyst/electrode layers for low-temperature solid oxide fuel cells (LT-SOFCs). The low pressure induced distinctive phenomena were illustrated for presenting the characteristics and advances of such coating technique. Micro-nano crystalline microstructure was generated on the plasma sprayed coatings simultaneously with phase transformation taking place. To study the effect of high temperature on such catalyst material, sintering experiments were carried out at 600–1000 °C. The results show that the ratio of x/y decreased when increasing temperature and sintering time because of the degradation of Li from Lix(Ni,Co)yO2 phase. The catalytic property and stability of the Lix(Ni,Co)yO2 at various temperatures were also discussed. 相似文献
7.
Abid Farooq Surendar Moogi Seong-Ho Jang Ashfaq Ahmed Young-Min Kim Hari Prasad Reddy Kannapu Soheil Valizadeh Sang-Chul Jung Su Shiung Lam Gwang Hoon Rhee Young-Kwon Park 《International Journal of Hydrogen Energy》2021,46(31):16603-16611
Present study evaluated the catalytic steam gasification of furniture waste to enhance the biohydrogen production. To do this, 10 wt% nickel loaded catalysts on the variety of supports (Al2O3, CeO2, CeO2-La2O3, and CeO2–ZrO2) were prepared by the novel solvent deficient method. The hydrogen selectivity (vol%) order of the catalysts was achieved as Ni/CeO2–ZrO2>Ni/CeO2>Ni/Al2O3?Ni/CeO2-La2O3. The best catalytic activity of Ni/CeO2–ZrO2 catalyst (~82 vol % H2 at 800 °C) was ascribed to the smaller size of nickel crystals, finely dispersed Ni on the catalyst surface, and Ce1-xZrxO2-δ solid solution. The role of Ce1-xZrxO2-δ solid solution in Ni/CeO2–ZrO2 catalyst was observed as bi-functional; acceleration of water-gas-shift and oxidation of carbon reaction. The high resistance of Ni/CeO2–ZrO2 towards the coke formation showed its potential to establish a cost-effective commercial-scale biomass steam gasification process. This study is expected to provide a promising solution for the disposal of furniture wastes for production of clean energy (biohydrogen). 相似文献
8.
Ce(1–x)Zr(x)O2 catalysts were prepared by co-precipitation method for deoxygenation (DO) of oleic acid. The CeO2/ZrO2 ratio was systematically varied to optimize Ce(1–x)Zr(x)O2 catalysts. Ce0.6Zr0.4O2 exhibited the highest oleic acid conversion as well as high selectivity to C9 ∼ C17 compounds (diesel fuel range) at the reaction temperature of 300 °C. The high activity/selectivity of Ce0.6Zr0.4O2 catalyst was correlated to its reducibility, oxygen storage capacity and crystallite size. 相似文献
9.
Harish C. Barshilia N. Selvakumar K.S. Rajam 《Solar Energy Materials & Solar Cells》2009,93(3):315-323
Spectrally selective AlxOy/Al/AlxOy multilayer absorber coatings were deposited on copper (Cu) and molybdenum (Mo) substrates using a pulsed sputtering system. The Al targets were sputtered using asymmetric bipolar-pulsed DC generators in Ar+O2 and Ar plasmas to deposit an AlxOy/Al/AlxOy coating. The compositions and thicknesses of the individual component layers were optimized to achieve high solar absorptance (α=0.950-0.970) and low thermal emittance (ε=0.05-0.08). The X-ray diffraction data in thin film mode showed an amorphous structure of the AlxOy/Al/AlxOy coating. The X-ray photoelectron spectroscopy data of the AlxOy/Al/AlxOy multilayer absorber indicated that the AlxOy layers present in the coating were non-stoichiometric. The optical constants (n and k) of the multilayer absorber were determined from the spectroscopic ellipsometric data. Drude's free-electron model was used for generating the theoretical dispersion of optical constants for Al films, while the Tauc-Lorentz model was used for modeling optical properties of the dielectric AlxOy layers. In order to study the thermal stability of the AlxOy/Al/AlxOy coatings, they were subjected to heat treatment (in air and vacuum) at different temperatures and durations. The multilayer absorber deposited on Cu substrates exhibited high solar selectivity (α/ε) of 0.901/0.06 even after heat-treatment in air up to 400 °C for 2 h. At 450 °C, the solar selectivity decreased significantly on Cu substrates (e.g., α/ε=0.790/0.07). The coatings deposited on Mo substrates were thermally stable up to 800 °C in vacuum with a solar selectivity of 0.934/0.05. The structural stability of the absorber coatings heat treated in air (up to 400 °C) and vacuum (up to 800 °C) was confirmed by micro-Raman spectroscopy measurements. Studies on the accelerated aging tests suggested that the absorber coatings on Cu were stable in air up to 75 h at 300 °C and the service lifetime of the multilayer absorber was predicted to be more than 25 years. Further, the activation energy for the degradation of the multilayer absorber heat treated for longer durations in air is of the order of 64 kJ/mol. 相似文献
10.
Jeong Gil Seo Min Hye Youn Sunyoung Park Jin Suk Chung In Kyu Song 《International Journal of Hydrogen Energy》2009,34(9):3755-3763
Al2O3–ZrO2 (AZ) xerogel supports prepared by a sol-gel method were calcined at various temperatures. Ni/Al2O3–ZrO2 (Ni/AZ) catalysts were then prepared by an impregnation method for use in hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of calcination temperature of AZ supports on the catalytic performance of Ni/AZ catalysts in the steam reforming of LNG was investigated. Crystalline phase of AZ supports was transformed in the sequence of amorphous γ-Al2O3 and amorphous ZrO2 → θ-Al2O3 and tetragonal ZrO2 → (θ + α)-Al2O3 and (tetragonal + monoclinic) ZrO2 → α-Al2O3 and (tetragonal + monoclinic) ZrO2 with increasing calcination temperature from 700 to 1300 °C. Nickel oxide species were strongly bound to γ-Al2O3 and θ-Al2O3 in the Ni/AZ catalysts through the formation of solid solution. In the steam reforming of LNG, both LNG conversion and hydrogen composition in dry gas showed volcano-shaped curves with respect to calcination temperature of AZ supports. Nickel surface area of Ni/AZ catalysts was well correlated with catalytic performance of the catalysts. Among the catalysts tested, Ni/AZ1000 (nickel catalyst supported on AZ support that had been calcined at 1000 °C) with the highest nickel surface area showed the best catalytic performance. Well-developed and pure tetragonal phase of ZrO2 in the AZ1000 support played an important role in the adsorption of steam and the subsequent spillover of steam from the support to the active nickel. 相似文献
11.
《International Journal of Hydrogen Energy》2020,45(16):9592-9602
Developing the catalysts for methanol steam reforming (MSR) via interfacial construction still remains many challenges. In this study, the effects of ZnO content on the performance of ZnyCe1Zr9Ox were studied for MSR. The best-performing Zn1Ce1Zr9Ox catalyst exhibited full methanol conversion and higher H2 production rate of 0.31 mol·h−1·gcat−1 at 400 °C. Characterization results revealed the synergistic effect among ZnO, CeO2 and ZrO2 after forming a solid solution and the incorporation of Zn2+ into Ce1Zr9Ox matrix not only modulate the ratio of surface OLatt/OAds, but also generate new Zn–O–Zr interfacial structure corresponding to the lattice/bridge oxygen to increase the selectivity of CO2. The excess oxygen vacancies on the samples surface favor the decomposition of methanol to generate the undesired CO. This study proposes a new design strategy for developing highly efficient composite MSR catalysts by control of the lattice/bridge oxygen and surface oxygen vacancy. 相似文献
12.
Titanium oxycarbide (TiCxOy) has attracted much attention recently as a soluble anode used in the USTB (University of Science and Technology Beijing) or MER (Materials and Electrochemical Research) molten‐salt electrolysis process to produce sponge titanium. The present study aimed to investigate the production of titanium oxycarbide from TiO2 by using CH4–H2 gas mixture, and both thermodynamic and experimental studies were carried out. First, thermodynamic analysis in the TiO2–CH4–H2 system was performed by the method of equilibrium calculation. The analysis indicated that TiO2 could be ultimately reduced and carbonized to TiCxOy by CH4 and H2 gas at temperature above 1200°C, and the increase of temperature was theoretically favorable to the final carbonization extent of TiCxOy. The experimental process involved the reduction of both pure TiO2 powder and TiO2 with additives using methane–hydrogen gas mixture in the temperature range from 1200°C to 1450°C. Experimental results showed that pure TiO2 could be reduced completely to TiCxOy at 1350°C and above after 8‐hour reduction. It was also found that the reduction extent of TiO2 increased with increasing time and temperature when at a low temperature range; however, a much higher temperature (above 1350°C) would hinder further carbonization for the production of deposited carbon. Addition of iron oxides to TiO2 powders strongly facilitated the reduction reaction, even prompting the reaction of TiO2 to TiCxOy completely at only 1200°C after 8‐hour reduction. The gas‐solid reaction provided a simple and quick way to produce titanium oxycarbide. 相似文献
13.
《International Journal of Hydrogen Energy》2021,46(79):39236-39250
In this work complex metal-oxide catalysts with the general formula 5 wt% Ni/Ce0·75Zr0.25-x(Nb,Ti)xO2-δ were synthesized by the solvothermal method using supercritical alcohols followed by nickel deposition. The catalysts were characterized and studied in ethanol dry reforming reaction (EDR) in the temperature range 600–750 °C. XRD and TEM showed that the synthesis method provides incorporation of doping cations into the ceria-zirconia fluorite structure, leading to mixed oxides formation. The effect of doping cations on structural and surface properties of 5 wt% Ni/Ce0·75Zr0.25-x(Nb,Ti)xO2-δ and activity in the EDR reaction was investigated. Oxygen deficiency δ increases with the introduction of titanium and niobium cations, which contributes to the bifunctional reforming mechanism implementation with rapid oxidation of coke precursors and activation of СО2 at surface oxygen vacancies. TPO-O2 analysis after reaction showed no carbon formation above 700 °C, and a few carbon deposits (not exceeding 4%) even after significant catalyst deactivation at 600 °C. 相似文献
14.
《Journal of power sources》2006,159(1):49-54
In this study, undoped ZrO2 thin films were deposited on single-crystal silicon substrates using liquid phase deposition. The undoped films were formed by hydrolysis of zirconium sulfate (Zr(SO4)2·4H2O) in the presence of H2O. A continuous oxide film was obtained by controlling adequate (NH4)2S2O8 concentration. The deposited films were characterized by SEM, FT-IR, XRD and DTA. Typically, the films showed excellent adhesion to the substrate with uniform particle diameter about 150 nm. The thicknesses of ZrO2 film were about 200 nm after 10 h deposition at 30 °C. These films shows single tetragonal phase after heat treated at 600 °C. High annealing temperature (e.g. 750 °C) may result in the phase transformation of (t)-ZrO2 into (m)-ZrO2. 相似文献
15.
E.A. Filonova E.Yu. Pikalova T.Yu. Maksimchuk A.I. Vylkov S.M. Pikalov A. Maignan 《International Journal of Hydrogen Energy》2021,46(32):17037-17050
Complex oxides Nd1.6Ca0.4Ni1-yCuyO4+δ (y = 0.0–0.4) have been prepared by a pyrolysis of glycerol-nitrate compositions. According to the X-ray diffraction analysis, the materials are single-phase up to y = 0.3 and crystallize in an orthorhombic structure (Bmab) at room temperature. High-temperature studies assert that they all undergo a phase transition from orthorhombic to tetragonal (I4/mmm) structure in a range of 300–400 °C. With Cu doping, the over-stoichiometric oxygen content δ decreases from 0.07 (y = 0.0) down to 0.00 (y = 0.3). The studies on the compact samples reveal the maximum value of total conductivity (165 S cm?1 at 420 °C) and the minimum value of the linear coefficient of thermal expansion (11.9·10?6 K?1 in a range of 400–1000 °C in air) at y = 0.2. Chemical compatibility of the Nd1.6Cа0.4Ni1-yCuyO4+δ (y = 0.0, 0.2) oxides with oxygen- and proton conducting electrolytes (Ce0.9Gd0.1O1.95, Ce0.8Sm0.2O1.9 and BaCe0.5Zr0.3Y0.1Yb0.1O3-δ) up to a temperature of 1100 °C is demonstrated. 相似文献
16.
Nilgün
zer John P. Cronin Yong-Jin Yao Antoni P. Tomsia 《Solar Energy Materials & Solar Cells》1999,59(4):355
Highly transparent, uniform and corrosion resistant Al2O3 films were prepared on stainless-steel and quartz substrates by the sol–gel process from stable coating solutions using aluminum-sec-butoxide, Al(OBus)3 as precursor, acetylacetone, AcAcH as chelating agent and nitric acid, HNO3, as catalyzer. Films up to 1000 nm thick were prepared by multiple spin coating deposition, and were characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), optical spectroscopy and micro Vickers hardness test. XRD of the film heat treated at 400°C showed that they had an amorphous structure. XPS confirmed that they were stoichiometric Al2O3. The refractive index (n) and extinction coefficient (k) were found to be n=1.56±0.01 and k=0.003±0.0002 at 600 nm, respectively. The surface microhardness and corrosion resistance investigations showed that Al2O3 films improved the surface properties of stainless-steel substrates. 相似文献
17.
Optical properties of electrochromic all-solid-state devices 总被引:1,自引:0,他引:1
We have investigated the optical properties of an all-thin-film electrochromic device, with a thin film of ZrO2 acting as an ion conductor. The device also employed electrochromic layers of amorphous or crystalline WO3 and NiVxOyHz. Transmission (T) and reflection (R) spectra were recorded in the wavelength range 300–2500 nm at different intercalation levels, both for single films and complete devices. The results show that T decreases significantly upon intercalation in the WO3 thin films as well as in the devices. The reflectance only shows minor changes. 相似文献
18.
Thermochemical hydrogen production by a redox system of ZrO2-supported Co(II)-ferrite 总被引:2,自引:2,他引:2
The thermochemical two-step water splitting was examined on ZrO2-supported Co(II)-ferrites below 1400 °C, for purpose of converting solar high-temperature heat to clean hydrogen energy as storage and transport of solar energy. The ferrite on the ZrO2-support was thermally decomposed to the reduced phase of wustite at 1400 °C under an inert atmosphere. The reduced phase was reoxidized with steam on the ZrO2-support to generate hydrogen below 1000 °C in a separate step. The ZrO2-supporting alleviated the high-temperature sintering of iron oxide. As the results, the ZrO2-supported ferrite realized a greater reactivity and a better repeatability of the cyclic water splitting than the conventional unsupported ferrites. The CoxFe3−xO4/ZrO2 with the x value of around 0.4–0.7 was found to be the promising working material for the two-step water splitting when thermally reduced at 1400 °C under an inert atmosphere. 相似文献
19.
In this paper, a noble-metal-free electrocatalyst based on carbon-supported zirconium oxynitride (ZrOxNy/C) was prepared by ammonolysis of carbon-supported zirconia (ZrO2/C) at 950 °C and investigated as cathode electrocatalyst towards oxygen reduction reaction (ORR) in PEMFCs. The electrocatalyst was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. The catalytic activity of the catalyst towards ORR was investigated by using the rotating disk electrode (RDE) technique in an O2-saturated 0.5 M H2SO4 solution. The ZrOxNy/C electrocatalyst presented attractive catalytic activity for ORR. The onset potential of ZrOxNy/C electrocatalyst for oxygen reduction was 0.7 V versus RHE and the four-electron pathway for the ORR was achieved on the surface of ZrOxNy/C electrocatalyst. The ZrOxNy/C electrocatalyst showed a comparatively good cell performance to ORR in PEMFCs, especially when operated at a comparatively high temperature. 相似文献
20.
《International Journal of Hydrogen Energy》2019,44(36):20345-20354
Using a citrate-nitrate process, BaCe0.9-xZrxY0.1O3-δ (x = 0, 0.5, 0.6, 0.7 and 0.8) nanopowders were synthesized, on the basis of which proton-conducting solid electrolytes (average size of coherent scattering region (CSR) - 15–53 nm) were obtained by spark plasma sintering (SPS) at a low temperature (900°С). The dependence of phase composition, microstructure and electrophysical properties of the obtained samples on ZrO2 content and consolidation conditions was established. It was found that the BaCe0.4Zr0,5Y0.1O3-δ solid solution had the highest electrical conductivity among zirconium-containing ceramic materials in the studied concentration range. It was shown that SPS is a promising method for obtaining solid electrolytes for proton-conducting solid oxide fuel cells (PCFC) at lower temperatures (by 400–500°С), compared to traditionally-used temperature conditions (1400–1800 °C). 相似文献