Liquid phase oxidation of cyclohexane was carried out over copper pyrophosphate catalyst using hydrogen peroxide as an oxidant in CH
3CN at the temperature between 25 and 80
°C. It was found that ...appropriate surface hydrophobicity is the key factor for the excellent performance of the catalyst. Additionally, a significant improvement for the cyclohexane conversion in the presence of organic acid was observed.
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Liquid phase oxidation of cyclohexane was carried out under mild reaction condition over copper pyrophosphate catalyst in CH
3CN using hydrogen peroxide as an oxidant at the temperature between 25 and 80
°C. The copper pyrophosphate catalyst was characterized by means of XRD, FT-IR and water contact angle measurement. It was found that appropriate surface hydrophobicity is the key factor for the excellent performance of the catalyst. In addition, a significant improvement for the cyclohexane conversion in the presence of organic acid was observed.
At present, the exploration of renewable energy is a huge challenge, and water electrolysis is regarded as a promising method for producing hydrogen. However, the hydrogen evolution reaction (HER) ...has been hampered due to expensive Pt-based catalysts. Herein, the Fe2P-coated Ni2P/Co2P nanospheres with yolk-shelled structure were successfully synthesized according to a facile approach of doping transition metal elements and phosphating on the template Ni-Co nanospheres, successively. All samples were tested as HER catalysts at various pH environments. The results showed that the Fe2P-Ni2P/Co2P possesses superior electrocatalytic ability and good stability. The Fe2P-Ni2P/Co2P achieved the lower ηonset (overpotential at 1.0 mA cm−2) of 36.6, 64.2, and 65.9 mV, η10 (overpotential at 10 mA cm−2) of 89.7, 125, and 212 mV, and Tafel slopes of 48.0, 60.3, and 135 mV dec−1 in acidic, alkaline, and neutral solutions, respectively, exhibiting an excellent electrocatalytic activity of the multicomponent phosphides for HER.
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•Yolk-shelled nanospheres Fe2P-Ni2P/Co2P was synthesized by a template method.•The synergistic effect was used to improve the electrocatalytic performance.•Fe2P-Ni2P/Co2P had large surface area and high catalytic activity for HER.•Fe2P-Ni2P/Co2P had satisfactory HER performance over a wide pH range.
Magnesium-based materials are favored by researchers because of their high hydrogen storage capacity, but they cannot be put to daily use because of their more demanding reaction conditions. ...Recently, the method to improve the hydrogen storage performance of MgH2 by catalyst doping has been widely investigated. In this paper, Co3O4 catalysts were prepared by homogeneous precipitation method. It was demonstrated that the Co3O4 catalyst could effectively improve the hydrogen storage performance of MgH2. According to the experimental results, the dehydrogenation onset temperature of the MgH2+15 wt% Co3O4 composite was about 200 °C, which was about 130 °C lower than that of pure MgH2, and the amount of dehydrogenation was 6.26 wt%. The dehydrogenation activation energy of the MgH2+15 wt% Co3O4 composite was reduced to 89.13 kJ/mol, which was about 45.7% lower than that of pure MgH2. After complete dehydrogenation, the composites started to absorb hydrogen at 50 °C with 6.2 wt%, while the activation energy of reabsorption was also reduced to 47.97 kJ/mol. After 10 cycles of MgH2+15 wt% Co3O4 composites, the hydrogen storage capacity of MgH2 could still be maintained at 99%, which indicated that it had good cycling stability. It was confirmed by various characterizations that Co3O4 was uniformly distributed on the MgH2 matrix after ball milling. After the first reaction, Co3O4 was converted to CoO, which was uniformly attached to the Mg/MgH2 surface and stabilized during the cycling process, continuing to provide active sites for hydrogen.
The hydrogen storage composite MgH2+Co3O4 was prepared in this study, and Co3O4 was uniformly distributed on the MgH2 matrix. In the first hydrogen release process, Co3O4 is gradually converted to CoO, and then in the hydrogen absorption process, hydrogen enters Mg. During the cycle, the CoO is in a stable state and evenly dispersed on the Mg/MgH2 surface, continuing to provide an active site for hydrogen. Display omitted
•Co3O4 with good air adaptation performance is applied to MgH2 system.•Composites started to release H2 at 200 °C and could start to absorb H2 at 50 °C.•The activation energy of de/hydrogenation was significantly reduced for composites.
•Co-upgrading of biomass and plastic vapors was conducted by zeolites coupled with NTP.•The synergy of Ru, Ti species and NTP enhanced formation of active atomic radicals.•Integration of mixed ...volatiles was strengthened to lower oxygen and increase yield.•TiHZ5 gave the maximum MAHs selectivity (64.19 %) and minimum PAHs selectivity (7.95 %).•Metal modified HZSM-5 induced by NTP had high coke-resistance and removed coke easily.
Co-upgrading of biomass and polyethylene -derived volatiles was conducted over HZSM-5 and its metal-modified versions, and NTP was introduced to enhance the conversion. The effects of metal species on the active radicals, organic yields, properties and compositions were explored. The Ru and Ti species, especially the low-valence titanium-oxides, increased atomic radicals, relieved the bottleneck of hydrogen transfer, and induced more volatiles into the radicals scale. The synergy of acid sites, metal species and NTP contributed to the integration of volatiles and exhibited promising potential in lowering oxygen and increasing organic yield. Specifically, TiHZ5 yielded the organic liquid of 58.73 % with the HHV of 38.73 MJ/kg, and RuHZ5 produced 51.70 % of organic liquid with the HHV of 36.96 MJ/kg. The synergy between SnHZ5 and NTP was so weak that it sacrificed partial yield to promote HHV. The Ru, Ti, and Sn modification increased the aromatic selectivity from 23.38 %–48.9 %, 72.14 % and 35.66 %, respectively, which caused the decrease of effective hydrogen to carbon ratios. Particularly, TiHZ5 gave the maximum MAHs selectivity of 64.19 % and minimum PAHs selectivity of 7.95 %. Besides, Ru, Ti and Sn modification decreased coking rate from 16.97 % to 7.04 %, 4.62 % and 8.46 %, respectively, and removal of coke became easier. This study provided a new waste-energy refinery way to reduce the disposal of waste plastics and relieve the dependence of fossil fuels.
Dielectric barrier discharge (DBD) was employed to assist to convert biomass into aromatic hydrocarbons under the vacuum pyrolysis and zeolite catalysis conditions. This study was to investigate the ...selectivity and stability of HZSM-5 modified by Ti, Ni, and Ni-Ti. The texture and acidity of different modified catalysts varied greatly. Ti modification strengthened the cracking removal of carbon and oxygen, while Ni-modified version improved hydrogen transfer capacity. Bimetallic modification increased the HHV to 36.93 MJ/kg, and obtained a compromised yield of 28.10%. Hydroxyl was difficult to completely remove due to hydrophilicity, carbonyl removal was better, and refined bio-oils had a high aromatic degree, of which, bimetallic modification increased the selectivity of MAHs to 76.61% and the refined bio-oil was more suitable to be used as gasoline additives. Although the aromatization performance of Ti-modified version was weaker than that of Ni-modified version, its anti-coking performance was better. The acidity adjustment of bimetallic modification cooperated with the synergistic effect of metal species and discharge, so that the difficulty of carbon deposition was increased significantly. The high-temperature catalytic coke was not distinguished and the low-temperature thermal coke mainly deposited on the outer surface was further reduced for bimetallic modified catalyst. Therefore, the Ni-Ti/HZSM-5 assisted by DBD exhibited better potential in improving the selectivity of aromatic hydrocarbons and enhancing the stability of zeolite catalyst.
•Metal modified HZSM-5 assisted by DBD was applied for one-stage aromatics production.•Ti and Ni modification respectively improved cracking and hydrogen transfer capacity.•Bimetallic modification increased MAHs selectivity to 76.61% and HHV to 36.93 MJ/kg.•Difficulty of carbon deposition was increased due to acid adjustment and DBD synergy.•Bimetallic version had no catalytic coke and reduced thermal coke on the outer surface.
An available approach to ameliorate the property of electrocatalysts for transition metal selenides (TMSs) is to transform their structure, morphology, and elemental composition, especially for ...hydrogen evolution reactions (HER), which can be a long-term task. In this work, Ni-Co nanospheres were synthesized by a hydrothermal method, and then in the synchronous processes of selenization and carbonization, it reacted with the peripherally coated melamine-copper complex, which was the reactant between melamine and copper ions. Ultimately, CoSe2/NiSe2@Cu2Se-NC nanospheres with a core-shell structure were synthesized after annealing process. This special structure provided more active attachment sites, enabling CoSe2/NiSe2@Cu2Se-NC to exhibit excellent HER properties under wide-pH range. Especially, in acidic conditions, it had a low initial potential of 41.0 mV, a small Tafel slope value of 48.7 mV dec–1, and a long service life. The proposed scheme indicates that a new approach will be added to the synthesis of electrocatalysts based on TMSs.
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•CoSe2/NiSe2@Cu2Se-NC core-shell nanosphere was synthesized by a facile method.•The unique structure and synergistic effect enhanced the electrocatalytic performance.•CoSe2/NiSe2@Cu2Se-NC had large surface area and high catalytic activity for HER.•CoSe2/NiSe2@Cu2Se-NC had satisfactory HER performance over a wide pH range.
In recent years, graphite containing some proportion of SiOx-based materials for lithium-ion batteries has been investigated widely owing to its high specific capacity. An efficient binder is ...critical to maintain both the electronic and mechanical integrity of the SiOx-based graphite composite anode electrodes. In this study, we present a discussion on the water-soluble binders of styrene butadiene rubber (SBR) and poly acrylic acid (PAA) in a 15% SiOx–graphite composite anode with half cell (coin) and high voltage pouch battery. The peeling strength of the anode electrode using two binders was measured. The first coulombic efficiency and discharge specific capacity of SiOx–graphite was 83.6% and 626.5 mA h g−1 using the SBR as binder, while 81.2% and 636.1 mA h g−1 using the PAA binder, respectively. Based on the results from EIS, rate performance and the mechanism of the SBR emulsion binder, SBR binder is more conducive to the transfer of electrons and ions on the electrodes. In practical applications (high voltage pouch battery), the batteries with the PAA binder show better cycle performance and achieve lower swelling (7.49%) compared with those with the SBR binder (9.56%) at the 450th cycle in the range of 2.75–4.35 V.
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