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11.
Kuikui Wang Guanglei Wu Haijie Cao Hongliang Li Xiusong Zhao 《International Journal of Hydrogen Energy》2018,43(15):7440-7446
In this study, we used a combination of graphene oxide-based porous carbon (GC) and titanium chloride (TiCl3) to improve the reversible dehydrogenation properties of magnesium hydride (MgH2). Examining the effects of GC and TiCl3 on the hydrogen storage properties of MgH2, the study found GC was a useful additive as confinement medium for promoting the reversible dehydrogenation of MgH2. And TiCl3 was an efficient catalytic dopant. A series of controlled experiments were carried out to optimize the sample preparation method and the addition amount of GC and TiCl3. In comparison with the neat MgH2 system, the MgH2/GC-TiCl3 composite prepared under optimized conditions exhibited enhanced dehydrogenation kinetics and lower dehydrogenation temperature. A combination of phase/microstructure/chemical state analyses has been conducted to gain insight into the promoting effects of GC and TiCl3 on the reversible dehydrogenation of MgH2. Our study found that GC was a useful scaffold material for tailoring the nanophase structure of MgH2. And TiCl3 played an efficient catalytic effect. Therefore, the remarkably improved dehydrogenation properties of MgH2 should be attributed to the synergetic effects of nanoconfinement and catalysis. 相似文献
12.
《中国稀土学报(英文版)》2020,38(4):384-394
In this paper,CeO_2 with a pore size of 2-4 nm was synthesized by hydrothermal method.The CeO_2 modified graphene-supported Pt catalyst was prepared by the microwave-assisted ethylene glycol reduction chloroplatinic acid method,and the effect of the addition of CeO_2 prepared by different hydrothermal reaction time on the catalytic performance of Pt-based catalysts was investigated.The microstructures of CeO_2 and catalysts were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),specific surface area and pore size analyzer(BET),scanning electron microscopy(SEM) and electron spectroscopy(EDAX),transmission electron microscopy(TEM),and the catalysts electrochemical performance was tested by electrochemical workstation.The results show that the catalytic performance of the four catalysts with CeO_2 is better than that of the catalyst without CeO_2.Adding CeO_2 with a specific surface area of 120.15 m~2/g prepared by hydrothermal reaction time of 39 h to Pt/C synthesis catalyst,its electrocatalytic performance,stability and resistance to poisoning are the best.The electrochemical active surface area is 102.83 m~2/g,the peak current density of ethanol oxidation is 757.17 A/g and steady-state current density of 1100 s is 108.17 A/g which shows the lowest activation energy for ethanol oxidation reaction.When the cyclic voltammogram is scanned for 500 cycles,the oxidation peak current density retention rate is 87.74%. 相似文献
13.
14.
Sania Saheli Ali Reza Rezvani Azim Malekzadeh Michal Dusek Vaclav Eigner 《International Journal of Hydrogen Energy》2018,43(2):685-694
The silica- and alumina-supported Co–Zn catalysts were synthesized by thermal decomposition of new inorganic precursors [Co4.32Zn1.68(HCO2)18(C2H8N)6]/SiO2 or Al2O3. A novel coordination polymer formulated as [Co4.32Zn1.68(HCO2)18(C2H8N)6] (1) was prepared using the solvothermal technique and characterized by elemental analysis, FT-infrared spectroscopy. Thermal stability of the complex 1 was investigated by thermogravimetric analysis and differential scanning calorimetry, and its structure was determined by single-crystal X-ray diffraction. Characterization of catalysts was carried out using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET specific surface area. The catalysts were evaluated for Fischer–Tropsch synthesis (FTS) in the temperature range 200–300 °C. The results revealed that the synthesized catalysts have higher selectivity to the desired products at 260 °C. The performance of the catalysts was compared to those of catalysts constructed via impregnation method and the fabricated catalysts show higher activity and selectivity than the reference catalysts. 相似文献
15.
The activity of ceramic honeycombs with varying material composition and degree of utilization is compared on a suitable model gas in a test plant. The tested honeycombs are standard products that have not been surface‐treated in any way. A propane‐air mixture was fed to the test plant and then oxidized in a high‐temperature furnace. The analysis of the conversion rate over the reaction temperature showed remarkable differences in activity. The honeycomb with the most promising results was further investigated with the exhaust gas from the drying process of a waste treatment plant. Finally, the activity of this honeycomb was assessed in a large‐scale trial in an existing running regenerative thermal oxidizer. 相似文献
16.
《International Journal of Hydrogen Energy》2021,46(60):31054-31066
Herein, catalytic aqueous phase photoreforming of cellulose was carried out over Pt/m-TiO2 (i.e., mixed phase of anatase and rutile) and Pt/anatase catalysts to investigate the effect of the TiO2 support structure and Pt loading on the production of H2. The effect of the TiO2 support on the properties of the resulting Pt/TiO2 catalysts (such as actual Pt loading and BET surface area) was not significant. At low Pt loading of 0.16 wt.%, the TiO2 supports affected the sub-nanometre Pt structures which was confirmed by the diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) characterisation (using CO as the probe). Conversely, the effect of TiO2 supports on larger Pt particles (on 1 wt.% catalysts) was insignificant possibly due to the reduced effect of restructuration of bigger Pt particles on the TiO2 supports. With an increase in Pt loading from 0.16 wt% to 1.00 wt.%, the normalised H2 production rate (with respect to the actual supported Pt amount and specific surface area of the catalysts) showed a decreasing trend over the two types of the catalysts, i.e., from 10.6 to 1.4 μmol h−1 m−2 mgPt−1 for Pt/m-TiO2, and from 8.5 to 1.2 μmol h−1 m−2 mgPt−1 for Pt/anatase. Specifically, large Pt particle sizes reduced the CO2/H2 production from cellulose photoreforming over both Pt/m-TiO2 and Pt/anatase catalysts, indicting an important role played by Pt particle size in photoreforming. Interestingly, in this study, the m-TiO2 supported catalysts only showed the benefits of enhanced charge separation across the phase junction in producing H2 with small Pt particles (at sub-nanometre), whilst, when large Pt particles (at around 1–2 nm) were supported, such a benefit was not significant in cellulose photoreforming. The promoting effect of small, sub-nm particles is attributed to the better capture of photoelectrons from bulk TiO2 and better activity of H+ coupling on small Pt particle. Further fundamental study on such guest-host interactions is devised to optimise Pt/TiO2 catalysts for improving H2 production from photoreforming reactions. 相似文献
17.
A hybrid multiphase model is developed to simulate the simultaneous momentum, heat and mass transfer and heterogeneous catalyzed reaction in structured catalytic porous materials. The approach relies on the combination of the volume of fluid (VOF) and Eulerian–Eulerian models, and several plug-in field functions. The VOF method is used to capture the gas–liquid interface motion, and the Eulerian–Eulerian framework solves the temperature and chemical species concentration equations for each phase. The self-defined field functions utilize a single-domain approach to overcome convergence difficulty when applying the hybrid multiphase for a multi-domain problem. The method is then applied to investigate selective removal of specific species in multicomponent reactive evaporation process. The results show that the coupling of catalytic reaction and interface species mass transfer at the phase interface is conditional, and the coupling of catalytic reaction and momentum transfer across fluid–porous interface significantly affects the conversion rate of reactants. Based on the numerical results, a strategy is proposed for matching solid catalyst with operating condition in catalytic distillation application. 相似文献
18.
Chunsheng Wang Yishuang Wang Mingqiang Chen Defang Liang Zhonglian Yang Wen Cheng Zhiyuan Tang Jun Wang Han Zhang 《International Journal of Hydrogen Energy》2021,46(7):5852-5874
Given the continuing issues of environment and energy, methane dry reforming for syngas production have sparked interest among researchers, but struggled with the process immaturity owing to catalyst deactivation. This review summarizes the recent advances in the development of efficient and stable catalysts with strong resistance to coking and metal sintering, including the application of novel materials, the assessment of advanced characterizations and the compatibility to improved reaction system. One feasible option is the crystalline oxide catalysts (perovskite, pyrochlore, spinel and LDHs), which feature a fine metal dispersion and surface confinement effect via a metal exsolution strategy and exhibit superior reactivity and stability. Some new materials (h-BN, clays and MOFs) also extend the option because of their unique morphology and microstructure. It also is elaborated that progresses were achieved in advanced characterizations application, leading to success in the establishment of reaction mechanisms and attributions to the formed robust catalysts. In addition, the perspective described the upgrade of reaction system to a higher reaction efficiency and milder reaction conditions. The combination of efficient reaction systems and robust catalysts paves a way for a scaling-up application of the process. 相似文献
19.
Zohal Safaei Mahmoudabadi Alimorad Rashidi Mohammad Panahi 《International Journal of Hydrogen Energy》2021,46(7):5270-5285
Highly active ReS2 nanocatalysts were prepared by CVD method and characterized by XRD, BET -BJH, Raman spectroscopy, XPS, TPR, NH3-TPD, SEM, and HRTEM techniques. Catalytic activities were used in upgrading heavy crude oil using methane as hydrogen source. The results showed a significant increase in API and decrease in sulfur and nitrogen content of crude oil. RSM technique was used to investigate the interactive effects of temperature (200–400 °C), pressure (20–40 bar) and dosage of nanocatalyst (0.5–2 wt. %) on the performance of HDS reaction. The results represent that the maximum predicted HDS activity (74.375%) was estimated under the optimal conditions (400 °C, 20 bars, and 2 wt % of nanocatalyst). Also, the effect of reaction temperature, pressure and dosage of ReS2 nanorods catalyst on HDN of heavy crude oil was investigated and highest efficiency in the HDN process (93%) occurred at 400 °C and 40 bar using 2 wt % ReS2. 相似文献
20.
Wei-Je Huang Ching-Tsung Yu Wen-Jenn Sheu Yen-Cho Chen 《International Journal of Hydrogen Energy》2021,46(31):16522-16533
The effect of non-uniform temperature on the sorption-enhanced steam methane reforming (SE-SMR) in a tubular fixed-bed reactor with a constant wall temperature of 600 °C is investigated numerically by an experimentally verified unsteady two-dimensional model. The reactor uses Ni/Al2O3 as the reforming catalyst and CaO as the sorbent. The reaction of SMR is enhanced by removing the CO2 through the reaction of CaO + CO2 → CaCO3 based on the Le Chatelier's principle. A non-uniform temperature distribution instead of a uniform temperature in the reactor appears due to the rapid endothermic reaction of SMR followed by an exothermic reaction of CO2 sorption. For a small weight hourly space velocity (WHSV) of 0.67 h?1 before the CO2 breakthrough, both a low and a high temperature regions exist simultaneously in the catalyst/sorbent bed, and their sizes are enlarged and the temperature distribution is more non-uniform for a larger tube diameter (D). Both the CH4 conversion and the H2 molar fraction are slightly increased with the increase of D. Based on the parameters adopted in this work, the CH4 conversion, the H2 and CO molar fractions at D = 60 mm are 84.6%, 94.4%, and 0.63%, respectively. After CO2 breakthrough, the reaction of SMR dominates, and the reactor performance is remarkably reduced due to low reactor temperature.For a higher value of WHSV (4.03 h?1) before CO2 breakthrough, both the reaction times for SMR and CO2 sorption become much shorter. The size of low temperature region becomes larger, and the high temperature region inside the catalyst/sorbent bed doesn't exist for D ≥ 30 mm. The maximum temperature difference inside the catalyst/sorbent bed is greater than 67 °C. Both the CH4 conversion and H2 molar fraction are slightly decreased with the increase of D. However, this phenomenon is qualitatively opposite to that for small WHSV of 0.67 h?1. The CH4 conversion and H2 molar fraction at D = 60 mm are 52.6% and 78.7%, respectively, which are much lower than those for WHSV = 0.67 h?1. 相似文献