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排序方式: 共有1245条查询结果,搜索用时 15 毫秒
1.
对离子交换法和一步沉积法引进铈离子的系列Y分子筛进行了铈离子定位研究。建立了铈离子在Y分子筛中定位的简便有效的基础表征体系:利用Ce3d XPS谱获得Ce4+/Ce3+摩尔比,通过Ce3d谱及XPS定量结果分析铈离子在分子筛笼内外的存在情况;利用XRD和Py IR确定铈离子在笼内的定位。研究了不同方法引进不同含量铈离子的定位规律。结果表明,离子交换法较沉积法利于铈离子迁移进分子筛笼内,从而进一步迁移进β笼;Ce2O3质量分数为4%、8%、12%和14%时,离子交换法引进的铈离子基本能迁移进β笼。一步沉积法引进的Ce2O3质量分数为4%时,易进入β笼;更多的铈离子则易留在分子筛笼外,可用于防止重金属中毒。 相似文献
2.
Diesel is the main source of world transportation due to higher combustion efficiency, compliance, consistency and cost-economy. It is also a major contributor to the world prosperity since it is used extensively. Diesel engine’s emissions are the serious hazard to the world environment and it is measured to be the major causes of air pollution. The demand in biofuels for years created a scope for aloe vera into biodiesels. Aloe vera, having higher calorific value vnthan other plant sources used as biodiesels, enhanced us in making another alternative biodiesel, which has lesser emissions and better performance. In this research work, four biodiesel blends from aloe vera oil with cerium oxide additive are explored for their performance and emission characteristics. The results proved B30 (30% biodiesel, 68% diesel and 1% cerium oxide) gives good performance when compared to other blends. 相似文献
3.
The paper analyses the corrosion behaviour of naturally and artificially aged AA2024 alloy in NaCl solution and in the presence of an environment-friendly corrosion inhibitor, CeCl3. On the basis of the values of polarisation resistance and corrosion current density, the corrosion resistance of the protective inhibitor film is established as well as the general corrosion resistance of this aluminium alloy. Resistance to pit formation is determined based on the difference in pitting and corrosion potentials while resistance to pit growth is determined based on the amount of charge consumed during pit growth. A scanning electron microscope is used to examine the morphology of the pits formed during the pitting corrosion testing, as well as to determine the cerium content on intermetallic particles and the matrix AA2024 alloy. The corrosion behaviour of AA2024 alloy is investigated after different test periods in NaCl solution and in the same solution with the CeCl3 inhibitor. The corrosion resistance of both tempers of AA2024 alloy is more than one order of magnitude higher in the presence of CeCl3. An explanation of the observed differences in the corrosion behaviour of the naturally and artificially aged AA2024 alloy is proposed. Different corrosion behaviour of the alloy after different test periods is also explained. 相似文献
4.
《International Journal of Hydrogen Energy》2020,45(40):20568-20581
Four catalysts based on Ni and Ni–Ce supported on two γ-aluminas with different morphology (nanofibers and nanograins) have been prepared and studied in the dry reforming of simulated biogas. Catalysts were characterized by N2 physisorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), inductively coupled plasma with optical emission spectrometer (ICP-OES), chemisorption of H2 and elemental analysis (EA) to determine their most relevant physicochemical properties. Characterization results show that metallic Ni particles supported on nanofibered alumina (NFA) presents a higher dispersion and smaller size than that supported on the nanograiny alumina (NGA) probably due to the higher mesoporosity presented by the NFA support. On the other hand, the incorporation of Ce has a similar effect than the fibrous morphology, decreasing also the size of the Ni metallic particles and increasing their dispersion. In the dry reforming of synthetic biogas (CH4/CO2 = 1.5) the nanofibered alumina containing 5 wt% Ni and 1.5 wt% Ce (NiCe/NFA) showed the highest catalytic activity at 750 °C (98% CO2 conversion) and stability (7.7% nickel sinterization level and 2.9 wt% carbon deposition). The stability of this catalyst was also demonstrated at 750 °C during 55 h of reaction time with a loss of activity at the steady state under 2%. In addition, the catalyst was regenerated at 600 °C in oxygen flow, recovering completely its initial catalytic performance. The excellent catalytic behavior of NiCe/NFA material has been related to the fibrous morphology of the alumina support, which promotes a better dispersion of the supported Ni metal particles, decreasing their size and increasing the number of actives sites where dry reforming reaction can take place. In addition, the incorporation of Ce seems to have also an important role by increasing the Ni-support interactions, decreasing sinterization of the metallic Ni particles and coke deposition. The contribution of both effects (morphology and Ce), separately and in combination, have been proved to enhance significantly the catalytic activity and stability of the synthesized catalysts in the dry reforming of simulated biogas. 相似文献
5.
Zahra Ghahramani Amir Masoud Arabi Mahdi Shafiee Afarani Mohammad Mahdavian 《International Journal of Applied Ceramic Technology》2020,17(3):1514-1521
In this study, combustion synthesis of cerium oxide nanoparticles was reported using cerium nitrate hexahydrate as starting material as well as urea, glycine, glucose, and citric acid as fuels. The influence of fuel type on structure, microstructure, band gap, and corrosion inhibition was investigated. X-ray diffraction (XRD) patterns and scanning electron microscopy micrographs showed that CeO2 nanoparticles with different morphologies were obtained depending on the fuel type. Microstructural changes from unreacted gel to sponge-like morphologies were resulted by varying the fuel type from urea, glycine, and glucose to citric acid. In addition to Ce–O bonds, Fourier transform infrared analysis showed carbon bonds of carbonaceous compositions from incomplete combustion which were declined during combustion reaction. Furthermore, corrosion analyses showed that samples synthesized using urea fuel released the most Ce+4 ions and could have better protection than other samples. 相似文献
6.
Near- and short-wave IR emission spectra of printed cotton/nylon blend fabrics coated with inorganic compounds in order to tune their diffuse reflectance behavior to the ones with woodland and desert backgrounds are investigated. In this regard, cotton/nylon blend fabrics printed with a four-color digital pattern were used as the substrate, and different concentrations of zirconium and cerium dioxide (ZrO2 and CeO2) with and without citric acid as a cross-linker were loaded on these fabrics using the pad-dry-cure method. The diffuse reflectance of the coated fabrics with various concentrations of nanoparticles and a cross-linker was first measured by near-infrared (NIR) diffuse reflectance spectroscopy (DRS). Then, fabrics with an optimum concentration of nanoparticles and appropriate reflectivity profiles similar to woodland and desert were investigated by field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), washing, and rubbing fastness properties. In general, NIR and short-wave infrared (SWIR) reflectance of fabrics coated with ZrO2 and CeO2 nanoparticles in range of 1% to 1.5% (w/v [%]) was suitable for matching with different environments. According to the findings obtained from the durability test, it was concluded that the washing fastness of the treated fabrics with CeO2 nanoparticles was excellent in both environments. FE-SEM images of the treated fabrics containing ZrO2 and CeO2 indicated that the presence of nanoparticles on the surface of fabrics in woodland patterns was greater than the desert ones. However, the coated fabrics with CeO2 and citric acid in the woodland pattern have shown better dispersion with a mean particle size of 30 to 60 nm. 相似文献
7.
Xia Liu Xuemei Pan Demian I. Njoku Kelechi J. Uwakwe Yugui Zheng 《Journal of Adhesion Science and Technology》2020,34(19):2047-2074
AbstractThe corrosion inhibition and adsorption behavior of glutamic acid (Glu), glutamine (Gln), and their cerium complexes: cerium glutamate (Ce(Glu)) and cerium glutamine (Ce(Gln)) on mild steel in 0.5?M HCl solutions were studied at 25 and 55?°C and concentration range of 25–200?ppm using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopic (EIS) techniques. The inhibition efficiency was found to be dependent on the concentration and temperature of the system. The potentiodynamic polarization results suggest that the compounds act as mixed-type inhibitors with dominant cathodic inhibition. The mechanism of adsorption deduced from the variation of inhibition efficiency with temperature, as well as the activation parameters, suggest significant physisorption of the inhibitor molecules on the metal surface. The experimental data adhere to the Langmuir and El-Awady et al. kinetic adsorption models. The extent of inhibition was found to be Ce-Gln?>?Gln and Ce-Glu?>?Glu. The scanning electron microscope was employed for the morphological studies and the characteristic of the protective layer on the steel surface verified using UV-Vis spectroscopy and FTIR spectroscopy. Adsorption of the inhibitors on Fe (110) surface was evaluated theoretically. 相似文献
8.
《中国有色金属学会会刊》2022,32(12):4156-4170
A new magnetic mesoporous As(III) adsorbent of Fe3O4@SiO2@Ce-ZrO2 was prepared by solvothermal and sol-gel method. The core-shell adsorbent presented a high specific surface area (168.2 m2/g) and fast magnetic separation performance (5.37 A·m2/kg). Compared with Fe3O4@SiO2@ZrO2, the Ce-doped sample exhibited 12%-23% increase in As(III) uptake over pH 3-11, which was mainly attributed to the formation of bimetal M—O—As complexes. The coexisted and weakened As(III) adsorption, Ca2+ worked oppositely, but the impact of Cl- and was negligible. The As(III) maximum adsorption capacity was 24.52 mg/g at 313 K with an initial As(III) concentration of 5 mg/L at pH 7, and its kinetics was well fitted by the pseudo-second-order model. Moreover, the adsorbent exhibited remarkable recyclability. It is suggested that Fe3O4@SiO2@Ce-ZrO2 is a promising adsorbent for the advanced treatment of As(III) contaminated wastewater. 相似文献
9.
ABSTRACTInjection timing (IT) is a vital factor among different injection parameters which governs the emissions and performance factors of the engine. This work portrays the effect of IT on cerium oxide nanoparticle doped Waste Cooking Palm Oil biodiesel and diesel blends. The doping is made at 30, 60 and 90?ppm. The modified fuels are introduced in reducing IT of 19°, 21° and 23°bTDC. 1500?rpm engine is made use in this study. Results revealed a significant reduction in emissions (CO, NOX, HC and Smoke) at IT?=?23°bTDC. Furthermore, performance (BSFC, BTE) is improved for fuel blends at IT?=?23°bTDC. 相似文献
10.