排序方式: 共有66条查询结果,搜索用时 15 毫秒
41.
Methane dry reforming was studied over nanostructure bimetallic Ni‐Co‐MgO catalysts. The catalysts were prepared by coprecipitation with different Ni‐Co contents and characterized by XRD, BET, N2 adsorption/desorption, temperature‐programmed reduction (TPR), SEM, and temperature‐programmed oxidation (TPO) techniques. XRD results let conclude that all samples contained MgO crystallite phases. With a higher Ni content the intensity of the diffraction peaks became stronger, indicating growth of the crystallite size of the prepared solid solutions. BET analysis demonstrated that a higher Ni‐Co content decreased the surface area. The optimal catalyst could be determined which had the highest activity and a good stability in dry reforming reaction. 相似文献
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Ali Asghar Rownaghi Yun Hin Taufiq-Yap Fateme Rezaei 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2009,155(1-2):514-522
In this paper, we have developed a simple, low-cost, template-free and surfactant-free solvothermal process for synthesis of vanadyl hydrogen phosphate hemihydrate (VOHPO4·0.5H2O) with well defined crystal size. The synthesis was performed by reaction of VPO4·2H2O with an aliphatic alcohol (isobutyl alcohol, 1-pentanol, 1-hexanol, 1-heptanol or 1-decanol). This afforded well crystallized VOHPO4·0.5H2O by solvothermal methods at 120 °C temperature. This new method significantly reduced the preparation time and lowered production temperature (50%) of catalyst precursor (VOHPO4·0.5H2O) when compared to conventional hydrothermal synthesis methods. By varying the reducing agent, the solvothermal evolution process from layered tetragonal phase VOPO4·2H2O to orthorhombic phase VOHPO4·0.5H2O was observed. It was found that the length of carbon chain in an alcohol in the solvothermal condition had a great impact on chemical and physical properties of resulting catalysts. Interestingly, there was no trace of VO(H2PO4)2 an impurity noted to be readily formed under solvothermal preparation condition. Therefore, this study introduces a more facile synthetic pathway to V(III) compounds. In addition, the microwave-synthesized catalysts exhibited some properties superior to those of conventionally synthesized catalyst such as better stability, crystallinity, and catalytic activity in the production of maleic anhydride. The characterization of both precursors and calcined catalysts was carried out using X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES), N2 physisorption, temperature programmed reduction (H2-TPR) and scanning electron microscopy (SEM). The XRD pattern of the active catalyst prepared by this solvothermal method confirmed the presence of smaller crystal size (between 6 and 13 nm along 0 2 0 planes) of vanadium phosphate catalyst with higher specific surface area. Finally, the yield of maleic anhydride was significantly increased from 29% for conventional catalyst to 44% for the new solvothermal catalyst. 相似文献
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Qasim Al-Naddaf Shane Lawson Ali A. Rownaghi Fateme Rezaei 《American Institute of Chemical Engineers》2020,66(9):e16297
In this investigation, the CO2 capture performances of zeolite 13X monoliths with 600 and 800 cells per square inch (cpsi) in the presence of SO2/NO impurities under dry and humid conditions were evaluated and compared with that of 13X beads. Dynamic breakthrough tests demonstrated a drastic reduction in CO2 capture capacity and deterioration of kinetics under dry-clean conditions, whereas, upon switching the feed from a clean gas to contaminated gas which contained SO2 and NO, different adsorption performance was observed. Specifically, in dry-contaminated mode, the adsorbents retained their capture capacities with comparable kinetics to that of dry-clean feed conditions, however, in humid-contaminated mode, the adsorbents experienced improved CO2 uptake and CO2/N2 selectivity, albeit at the expense of deteriorated kinetics. These findings indicate that the presence of SO2 and NO contaminants, especially SO2 contaminants, lead to dramatic changes in the adsorption performance of zeolite 13X monoliths, indicating the importance of evaluating adsorbent materials under realistic conditions. 相似文献
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CO2 sorption kinetics of poly(ethylenimine) (PEI)-impregnated MIL-101, γ-alumina, and UVM-7 silica were investigated by the zero-length column technique for the purpose of understanding the effect of amine content, adsorbent porosity, and adsorption temperature on CO2 sorption rates. Each of the adsorbents was impregnated with three different amine contents (20, 35, and 50 wt%) and the effective diffusion time constants were determined at 25°C. For each respective adsorbent, it was found that increasing the amine content results in diminished diffusion rates. Additionally, it was found that the pore size of the support has a profound effect on diffusional kinetics, where microporous MIL-101 yielded substantially slow desorption rates upon amine-functionalization compared to mesoporous γ-alumina. PEI-impregnated UVM-7 silica was further investigated at 50 and 75°C in order to provide insight into the effect of temperature on sorption kinetics. The results indicated that PEI-impregnated UVM-7 exhibited faster sorption kinetics at higher temperatures. Upon desorption, PEI-UVM-7 silica exhibited two distinct regions of mass-transfer control that occur at different sorption times. This is best explained by first the occurrence of surface diffusion followed by diffusion out of the bulky PEI polymer chains. The findings of this study provide novel kinetic characterizations on promising amino-adsorbents for carbon capture applications. 相似文献
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Le Huong Nguyen Serap Günes Helmut Neugebauer Niyazi Serdar Sariciftci Fateme Banishoeib Anja Henckens Thomas Cleij Laurence Lutsen Dirk Vanderzande 《Solar Energy Materials & Solar Cells》2006,90(17):2815-2828
Photophysical studies and photovoltaic devices on a low bandgap, high-charge carrier mobility poly(thienylene vinylene) (PTV), prepared from a soluble precursor polymer synthesised via the “dithiocarbamate route”, are reported. In composites with an electron acceptor ([6,6]-phenyl C61-butyric acid methyl ester (PCBM), a soluble fullerene derivative), photoinduced absorption characteristic for charged excitations together with photoluminescence quenching are observed indicating photoinduced electron transfer. The “bulk heterojunction” photovoltaic devices using PTV and PCBM composites show short-circuit currents up to 4 mA/cm2 under AM 1.5 white-light illumination. The photocurrent spectrum of the photovoltaic device shows an onset about 1.65 eV (750 nm), which corresponds to the absorption spectrum of the polymer. 相似文献
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Mohammadreza Nademi Rostami Saeed Dinarvand 《International Journal of Hydrogen Energy》2018,43(46):21627-21628
The present comment concerns the improvement of the similarity energy equation that has been written incorrectly in the article by Khan et al. [1]. In this note, we derive its correct form and show that such a mistake may affect the results. 相似文献
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Fateme Heidari Seyed Hessameddin Zegordi Reza Tavakkoli-Moghaddam 《Journal of Intelligent Manufacturing》2018,29(5):1155-1170
Uncertainty and non-deterministic nature of the real world makes planning and scheduling in cross-docks a very complicated task for decision makers. These constant changes that happen all the time, often, lead to an increase in costs and/or a decrease in efficiency. Most of the uncertainty in cross-docks is caused by un-known truck arrival times. In this study we address the problem of scheduling incoming and outgoing trucks at a cross-dock facility, when vehicle arrival times are unknown, through a cost-stable scheduling strategy. Two meta-heuristics, MODE and NSGA-II, are used for solving the designed sample problems and are compared with a random search based genetic algorithm existing in the literature. Finally, performance of each algorithm is measured and analyzed using four metrics: quality, spacing, diversification and mean ideal distance. The results indicate that the proposed model MODE algorithm performs better in comparison with the other two methods. 相似文献