The reduction pathway of Co catalysts supported on untreated SiO2 along with two pretreated SiO2 support materials was investigated. In situ XRD studies clearly showed the likely reduction pathways of the cobalt oxides on the untreated SiO2, ethylene glycol pretreated SiO2, and annealing pretreated SiO2 supports. Ethylene glycol pretreated SiO2-supported Co (Co/E–SiO2) catalyst showed smaller metal crystallites, highly dispersed Co and high Co(hcp)/Co(fcc) ratio because of the high percentage of non-H-bonded silanols; however, the high percentage of the non-H-bonded silanols created a strong Co-SiO2 interaction which caused a low degree of reduction of CoO resulting in lower FT activity. In contrast, the annealing pretreated SiO2-supported Co (Co/A–SiO2) catalyst did not significantly increase the percentage of non-H-bonded silanols and Co(hcp)/Co(fcc) ratio when compared with Co/E–SiO2, but it exhibited a better catalytic activity during FTS.
Information technology and network technology have been applied extensively in the field of Commerce, which made electronic commerce become the main mode of business operation.In this circumstance, the international trade transaction structure has been affected extremely.By carrying out empirical analysis between China's e-commerce market scale and China's foreign trade structure, the conclusion can be got that e-commerce plays a positive effect on the optimization of foreign trade structure of China.Put forward countermeasures from different aspects which can promote the development of e-commerce in China.
There is an imperative need for top-performing materials with extraordinary adsorption selectivity and working capacity, in order to achieve productive adsorption of CF4 in a CF4/N2 mixture. In this work, the High-Throughput Grand Canonical Monte Carlo (HT-GCMC) simulation method and the Machine Learning (ML) method were employed to predict and screen the adsorption performance of 10 143 computation-ready experimental metal-organic frameworks (CoRE-MOFs) for separating CF4/N2 mixed gas. Through computational simulation and ML prediction, 15 and 73 highly promising adsorbents were selected out of the 690 randomly sampled MOFs and the CoRE-MOF database. The selection process was based on criteria that balanced favorable CF4 selectivity, working capacity, and regenerability: selectivity > 60, working capacity > 70 mg·g-1 (0.8 mmol·g-1) and regenerability > 70%. The maximum observed capacity of the 15 top evaluated metal-organic frameworks (MOFs) was: 52.85 mg·g-1 (0.6 mmol·g-1) at 1 bar; and 204.90 mg·g-1 (2.3 mmol·g-1) at 10 bar. The maximum working capacity was 152.05 mg·g-1 (1.7 mmol·g-1) and the highest selectivity reached was 118.12 (YEGCUJ) and 101.80 (VEHLIE) at 1 bar and 10 bar, respectively. Notably, the most promising MOFs exhibited elevated Zn content relative to the overall MOF population and also possessed a significant nitrogen content. This result should serve as a compelling motivation to further investigate the utilisation of MOFs with a high Zn content (e. g. zeolitic imidazolate frameworks), for enhanced adsorption applications.
The synthesis of multiwalled carbon nanotubes (MWCNTs) and carbon balls (CBs) catalyzed by ferrocene (Fc), Mo(CO)5L (L = CO, tBuNC), and bimetallic catalyst systems (Fc/M(CO)5tBuNC; M = W or Mo) was investigated. These reactions were carried out in flowing 5% H2 in Ar in the temperature range 700−900 °C. Under the reaction conditions, Fc yielded CNTs and CBs, while the M(CO)5L complexes yielded little carbonaceous material. Depending on the temperature and weight ratio of the metals used, mixtures of Fc and M(CO)5L generated varying amounts of CNTs and CBs. EDS and TEM analysis revealed the formation of large particles of Mo/Fe alloys. It was observed that the diameters of the CNTs catalyzed by Fc are smaller while the diameters of CBs are larger relative to the diameters of CNTs and CBs produced by the bimetallic catalyst systems. In all instances MWCNTs were produced, which contrasts with the single-walled CNTs produced by Fe/Mo-supported heterogeneous catalyst systems.
New carbon-based materials have drawn tremendous attention in several technological applications. Here, the synthesis of graphene-containing biochar was prepared through carbonation and activation processes, using pre-oxidized magnolia flowers. In particular, the activation method was conducted in copper foil under high pressure, which led to the high biochar yield and excellent electrical conductivity of biochar for graphene-containing hybrid. Furthermore, heteroatoms (including nitrogen and oxygen) were successfully doped into the biochar. As a result, the hybrid demonstrated excellent electrical properties, at high nitrogen (1.02 %) and oxygen levels (14.80 %). The as-prepared biochar was used to produce an all solid state symmetric superconductor with a capacitance of 261.8 F g-1 at a specific current of 0.5 A g-1 , and energy density of 6.9 Wh kg-1 at powder density of 20 kW kg-1 .The enhanced electrochemical performance was attributed to the positive effect of synergy between highly conductive graphene-containing biochar and heteroatoms doping
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