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161.
《International Journal of Hydrogen Energy》2019,44(34):18858-18865
This paper reports the experimental results on using TiO2 based Cu(II)-Schiff Base complex catalyst for hydrolysis of NaBH4. In the presence of Cu-Schiff Base complex which we reported in advance [1] and with titanium dioxide supports a novel catalyst named TiO2 supported 4-4′-Methylenbis (2,6-diethyl)aniline-3,5-di-tert-buthylsalisylaldimine-Cu complex is prepared, successfully. The synthesized catalyst was characterized by means of X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Brunauer-Emmett-Teller Surface Area Analysis (BET) and Fourier Transform Infrared Spectroscopy (FT-IR). The as prepared catalyst was employed to generate hydrogen through hydrolysis reaction of NaBH4. Effects of different parameters (e.g. amount of Cu-Schiff Base complex in all catalyst, percentage of NaBH4, percentage of NaOH, amount of TiO2 supported Cu-Schiff Base complex catalyst and different temperatures) are also investigated. A high apparent activation energy (Ea), 25,196 kJ.mol-1 is calculated for hydrolysis of NaBH4 at 20–50 °C. Hydrogen generation rate was 14,020 mL H2/gcat.min and 22,071 mL H2/gcat.min in order of 30 °C and 50 °C. 相似文献
162.
《International Journal of Hydrogen Energy》2019,44(13):6965-6977
Developing a highly active and stable Ni-based catalyst is still a challenge for the generation of on-site hydrogen through steam reforming of long-chained hydrocarbons, such as kerosene fuels. Ni nanoparticles (ca. 5 nm) on mesoporous alumina prepared by atomic layer deposition (ALD) were employed in steam reforming of n-dodecane, and exhibited a turnover frequency (TOF) of 477.6 h−1, whereas Ni nanoparticles on commercial alumina support prepared by impregnation method exhibited a TOF of 100 h−1. The high activity of ALD Ni catalysts was ascribed to high reduction degree, as confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and H2-chemisorption. A deactivation was also observed on the ALD prepared catalysts, which was ascribed to the weak metal-support interaction, as confirmed by H2 temperature-programmed reduction (TPR). The ALD Ni/Al2O3 catalysts were further modified with CeO2 and they showed enhanced stability with 8% deactivation degree in steam reforming of n-dodecane. Further characterizations of spent catalysts showed that the presence of CeO2 was favorable for stabilizing Ni nanoparticles by enhancing moderate metal-support interaction, and reducing the formation of coke on the interfaces of NiCeO2. 相似文献
163.
《International Journal of Hydrogen Energy》2019,44(16):8178-8187
Macaroon-like FeCo2O4 nanomaterial was prepared and used as electrocatalyst in direct glucose alkaline fuel cell (DGAFC), which exhibited high catalytic activity towards glucose oxidation reaction. Maximum power density of 35.91 W m−2 was achieved in the DGAFC equipped with a FeCo2O4 modified activated carbon (AC) anode, which was almost 151% higher than the control. Physical and electrochemical characterizations were performed to provide further understanding of the origin of its high activity. Our results show that the introduction of FeCo2O4 into the AC anode remarkably increase the exchange current density and reduce the charge transfer resistance. It is supposed that there is a synergistic effect between Fe (III) and Co (III), which accelerates electron transfer from glucose to external circuits. This study will promote the development of cost effective and environmentally benign catalysts for electrochemical energy applications. 相似文献
164.
《能源学会志》2019,92(5):1284-1293
Chemical looping gasification (CLG) of coal, in which oxygen is provided to coal by oxygen carriers directly, is a clean and efficient way to generate syngas. Thermo-gravimetric analysis (TGA) of lignite char with oxygen carriers was conducted in this work, and the experimental results indicated that the oxygen carriers, Ti0·5Mn0·5Fe2O4, MnFe2O4, FeTiO3 and Fe2TiO4, had a positive effect on CLG of lignite char. The effect of these oxygen carriers was discussed in the perspective of the crystal structure. XPS experiment was performed and the spectra of O 1s revealed the effect of different element on reactivity of spinel-based oxygen carriers. Five kinetic models, including Uniform Reaction (UR), Integrated Model (IM), Modified Random Pore Model (MRPM), Random Pore Model (RPM) and Modified Volumetric Model (MVM), were employed for revealing the reaction mechanism. MRPM had the highest correlation coefficient for each oxygen carrier, which means the introduction of the oxygen carriers effectively increases the active site of the reaction surface. 相似文献
165.
《International Journal of Hydrogen Energy》2019,44(59):31082-31093
Oxygen evolution reaction (OER) electrocatalysts play the critical role in efficiency and durability for different hydrogen production systems. We have successfully synthesized the earth abundant WO3 coupled with IrO2 as mixed oxide composite by a facile two-step chemical method. 50% reduction in noble metal contents (IW-50) followed by two times enhancement in activity, four-folds increase in bulk mass specific activity along with the stability of mixed oxide composite as compared to state –of –the art IrO2 catalyst are affirmed. Superior performance of mixed oxide composites are perceived due to four times increase in electrochemical surface area, reduction of Tafel slope, four-fold increase of turn over frequency, electronic distortion in Ir-4f spectrum of IW-50 along with the bridging of lattice oxygen atoms between iridium and tungsten metals. We believe that it would open up the new avenues for effective utilization of noble metal with high valence tungsten metal in corrosive environment. 相似文献
166.
《International Journal of Hydrogen Energy》2019,44(39):21999-22010
Nanosizing is efficient as the dual-tuning of thermodynamics and kinetics for Mg-based hydrogen storage materials. The in-situ synthesis of nanocomposites through hydrogen-induced decomposition from long-period stacking ordered phase is proved effective to achieve active nano-sized catalysts with uniform dispersion. In this study, the Mg93Cu7-xYx (x = 0.67, 1.33, and 2) alloys with equalized Mg–Mg2Cu eutectic and 14H long-period stacking ordered phase of Mg92Cu3.5Y4.5 are prepared. Its solidification path is determined as α-Mg, 14H–Mg2Cu pair and Mg–Mg2Cu eutectic. The increased Y/Cu atomic ratio lowers the first-cycle hydrogenation rate of the alloys due to the increased 14H–Mg2Cu structure and reduced Mg–Mg2Cu eutectic interfaces. After the hydrogen-induced decomposition of the long-period stacking ordered phase, MgCu2 and YH3 nanoparticles are in-situ formed, and the following activation process significantly accelerates. The YH3 nanoparticles partly decompose to YH2 at 300 °C in vacuum and Mg–Mg2Cu-YHx nanocomposites are in-situ formed. The nano-sized YH2 helps catalyze H2 dissociation and the YHx/Mg interfaces stimulate H diffusion and the nucleation of MgH2. Therefore, the Mg93Cu5Y2 composite shows the fastest absorption rates. However, due to the positive effect of YHx/Mg interfaces on H diffusion and the negative effect of YH3 nanophases on the hydride decomposition, the minimum activation energy of 115.43 kJ mol−1 is obtained for the desorption of the Mg93Cu5.67Y1.33 hydride. 相似文献
167.
《International Journal of Hydrogen Energy》2019,44(39):21673-21682
In order to design and synthesize oxygen reduction reaction catalysts with high activity and low cost, a series of Co–Mn-oxide/C catalysts with different Co:Mn ratios have been prepared using a hydrothermal method applied in sequential steps. The monotonically systematic trends of the catalysts’ phases, morphologies and particle sizes have been verified, and the trending of Mn ions and Co ions in different valence states follows the increasing Co:Mn ratio. Electrochemical performance of the catalysts in oxygen reduction reaction results in a volcano-type trend with an optimal Co:Mn ratio of 3 giving the best performance, which is comparable to that of commercial Pt/C. Lastly, a Koutecky-Levich approach has been employed to deduce the electron transfer values, in an attempt to rationalize their selectivity towards the varying 2 and 4 electron pathways. The systematic research is significant for understanding and designing a new generation of non-noble metal oxygen reduction reaction catalysts. 相似文献
168.
《International Journal of Hydrogen Energy》2019,44(1):325-331
Hydrogen uptake of pristine multi-walled carbon nanotubes is increased more than three-fold at 298 K and hydrogen pressure of 4.0 MPa, upon addition of hydrogen spillover catalyst manganese oxide, from 0.26 to 0.94 wt%. Simple and convenient in situ reduction method is used to prepare Mn-oxide/MWCNTs composite. XRD, FESEM, and TEM demonstrates nanostructural characterization of pristine MWCNTs and composite. TGA analysis of Mn-oxide/MWCNTs composites showed a single monotonous fall related to MWCNTs gasification. Enhancement of hydrogen storage capacity of composite is attributed to spillover mechanism owing to decoration of Mn-oxide nanoparticles on outer surface of MWCNTs. Hydrogen uptake follows monotonous dependence on hydrogen pressure. Oxide-MWCNTs composite not only shows high hydrogen storage capacity as compared to pristine, but also exhibit significant cyclic stability upon successive adsorption–desorption cycles. 相似文献
169.
《International Journal of Hydrogen Energy》2019,44(37):20857-20871
The present work investigates the performance of Re-promoted Nickel-based catalyst supported on calcium oxide for glycerol dry reforming reaction. The catalysts were prepared using wet impregnation method and their catalytic performance was tested in a packed bed reactor with CO2 to glycerol ratio (CGR) of 1–5, reaction temperature of 600–900 °C and gas hourly specific velocity (GHSV) of 1.44 × 104–7.20 × 104 ml gcat−1 s−1. The optimum operating temperature for both Ni/CaO and ReNi/CaO is 800 °C, with the GHSV of 3.6 × 104 mL gcat−1s−1. The optimum CGR for Ni/CaO and ReNi/CaO is 1.0 and 3.0, respectively. At this condition, hydrogen gas is directly produced from glycerol decomposition and indirectly from water-gas-shift reaction. After 2 h at the optimum conditions, 5% ReNi/CaO gives optimal glycerol conversion and hydrogen yield of approximately 61% and 56%, respectively, while in comparison to 15% Ni/CaO, the conversion and yield are 35 and 30%, respectively. Characterization of the spent catalysts showed the existence of whisker carbon from the CO2 hydrogenation and methanation processes. By comparing to 15% Ni/CaO, the addition of Re increases the acidic sites of the catalyst and enhanced the surface adsorption of OH group of the glycerol. The adsorbed glycerol on the catalyst surface would further react with the adsorbed CO2 to yield gases products. Thus, the catalytic activity improved significantly. 相似文献
170.
《International Journal of Hydrogen Energy》2023,48(41):15433-15446
In this study, three-dimensional ordered microporous silica supported p-lanthanum ferrite and n-ceria (n-CeO2@p-LaFeO3/3DOM SiO2) was successfully synthesized as a visible light-driven photocatalyst for activating peroxymonosulfate (PMS) to degrade Bisphenol A (BPA). In a wide pH range (2–12), the BPA degradation efficiency maintained at a high level, organic matter and natural inorganic ions had no significant negative impact. When the BPA concentration was as low as 2 mg·L−1, the removal rate in 60 min still reached 95.56%, indicating that the novel photocatalyst has potential application in the treatment of trace pollutants. The pore confinement effects of catalysts and the synergistic effect between LaFeO3 and CeO2 result in the excellent photocatalytic performance. We proposed the possible mechanism of BPA degradation, specifically involving the recognition and generation mechanism of reactive oxygen species (ROSs), adsorption processes and diffusion processes. In summary, the novel n-CeO2@p-LaFeO3/3DOM SiO2 would be a promising candidate photocatalytic material for practical sewage treatment. 相似文献