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81.
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
82.
随着科学技术的发展和经济水平的提高,人们对消防安全的认识日益增强.需要重视消防安全,做好消防管理,并采用先进的管理模式,在当前的消防管理模式下应用"智能消防",可以确保人民生命财产安全提供强有力的支持,使现代科学技术可以更好地融入到消防工作中,不仅可以提高火灾监控能力,还可以提高消防水平,对消防安全领域的发展具有重要意义,使传统消防逐步向智能消防转变,并不断升级. 相似文献
83.
Yan Luo Zeming Tang Guiqiang Cao Da Bi David P. Trudgeon Adeline Loh Xiaohong Li Qingxue Lai Yanyu Liang 《International Journal of Hydrogen Energy》2021,46(2):1997-2006
Atomically dispersed transition metals anchored on N-doped carbon have been successfully developed as promising electrocatalysts for acidic oxygen reduction reaction (ORR). Nonetheless, how to introduce and construct single-atomic active sites is still a big challenge. Herein, a novel concave dodecahedron catalyst of N-doped carbon (FeCuNC) with well confined atomically dispersed bivalent Fe sites was facilely developed via a Cu-assisted induced strategy. The obtained catalyst delivered outstanding ORR performance in 0.5 M H2SO4 media with a half-wave potential (E1/2) of 0.82 V (vs reversible hydrogen electrode, RHE), stemming from the highly active bivalent Fe-Nx sites with sufficient exposure and accessibility guaranteed by the high specific surface area and curved surface. This work provides a simple but efficient metal-assisted induced strategy to tune the configurations of atomically dispersed active sites as well as microscopy structures of carbon matrix to develop promising PGM-free catalysts for proton exchange membrane fuel cell (PEMFC) applications. 相似文献
84.
该文开展了Q 420十字组合截面角钢轴压试验研究组合角钢的稳定承载力性能.试验角钢规格分别为:L125×8、L140×12和L160×10,长细比为30~60,采用焊接十字填板.试验结果表明,组合角钢试件发生整体弯曲并伴随明显的局部屈曲变形,分肢角钢受力不均匀,分肢角钢应力比范围为1.04~1.31.然后,建立组合角钢的简化数值分析模型,模拟试件的轴压受力特性,并将模拟结果与试验结果进行对比.最后,基于研究结果提出采用修正长细比计算组合角钢稳定承载力,根据修正长细比的计算承载力与试验结果吻合较好,建议在实际工程中推广使用. 相似文献
85.
Dan Liang Nan Li Xiaofeng Dai Hong Zhang Honghai Hu 《International Journal of Food Science & Technology》2021,56(5):2432-2442
The prebiotic effects of potato resistant starches RS1, RS2, RS3a, RS3b and RS4 were studied using simulated gut fermentation in vitro. The intestinal microbial composition was significantly changed by resistant starch (RS) after 24-h fermentation. All RSs (P < 0.05) decreased the ratio of Firmicutes/Bacteroidetes (F/B), and RS2 exhibited the lowest value of 0.95 ± 0.07. The relative abundance of Bifidobacterium was significantly increased by RS4, whereas Megamonas and Prevotella were promoted by RS2. Further, RS4 produced the highest levels of acetate (138.34 µM), whereas RS2 produced the highest levels of propionate (41.45 µM) and butyrate (21.65 µM). However, Bifidobacterium did not promote the production of propionate or butyrate, even though it was proficient in fermenting RS. Megamonas and Prevotella were positively associated with the higher production of propionate and butyrate. Here, different RSs played key roles in promoting intestinal health, and RS2 especially showed more abundant probiotic functions. 相似文献
86.
利用PLC程序控制器的特性,对华阳一矿TD75型带式输送机进行控制.应用PLG程序控制器后,带式输送机的控制更加精准,提高了带式输送机传动的安全性、可靠性,为煤矿的高效生产奠定了基础. 相似文献
87.
The continuous and dense Ti–N compound layers with a thickness ranging from 0.7 to 2.1 μm were formed on the titanium by plasma nitriding at 700 °C for different times with hollow cathode discharge assistance. Scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the nitrided layer. XRD and XPS results showed that the compound layer was mainly composed of Ti2N phase. The corrosion current density of 4 h nitrided titanium was 0.016 μA/cm2 (cathode) and 0.03 μA/cm2 (anode), respectively. The electrical conductivity of samples was evaluated by means of the interfacial contact resistance (ICR). The value of 4 h nitrided titanium was 4.94 mΩ-cm2 which was much lower than that of original titanium 26.25 mΩ-cm2 under applied force of 150 Ncm?2 after corrosion test. The results showed that the electrical conductivity and corrosion resistance of the titanium bipolar plates (BPs) were apparently improved with the formation of Ti2N compound layer. 相似文献
88.
First-principles study on the dissolution and diffusion behavior of hydrogen in carbide precipitates
Yifan Li Xingming Zhang Tiantian Wu Jianfeng Tang Lei Deng Wei Li Liang Wang Huiqiu Deng Wangyu Hu 《International Journal of Hydrogen Energy》2021,46(42):22030-22039
To understand the hydrogen (H) behavior in the carbide precipitates, the dissolution and diffusion properties of interstitial H in the transition metal carbide (TMC; TM = Hf, Nb, Ta, Ti, V, and Zr) were studied by first-principles calculations. In these carbides, it can be seen that H tends to occupy the trigonal site (tri2-site) surrounded by three transition metal atoms and one carbon atom rather than the face center (fc-site) and the body center (bc-site) which with the larger space. We found that the bonding interaction between H atom and the nearest-neighbor (1NN) carbon atom is the dominant influence on the stability of H dissolution. Besides, we obtained the temperature-dependent solubility and diffusion coefficients of H in TMC and pure vanadium through Sievert's law and transition state theory. Compared with pure vanadium, H shows the worse solubility in TMC, and it is more difficult for hydrogen to migrate in TMC, but segregate toward the interface. Furthermore, it is interesting to note that, the diffusion barrier and the H solution energy show a linear relationship for transition metal carbides in the same period. These results can help us deepen the understanding of H behavior in vanadium alloys strengthened by carbide precipitates, and furtherly providing the theoretical guidance for the design of alloys with excellent performance. 相似文献
89.
90.
Guang Hu Fangnian Wang Qingxin Ba Jianjun Xiao Thomas Jordan 《International Journal of Hydrogen Energy》2021,46(46):23974-23987
An accurate prediction of the hydrogen behaviors in the accident and management process is a crucial topic for both the hydrogen safety assessment and safety analysis in the confined enclosure like the containment of the nuclear power plant (NPP). Hence, the hydrogen behaviors including the transient light gas release, stratification and dissolution in the TH22 test facility for the NPP containment are analyzed and compared using the 3-D CFD code GASFLOW-MPI in this study. In this paper, the light gas helium is adopted as a substitute for the hydrogen in the calculations in accordance with the experiment. Firstly, the detached eddy simulation (DES) turbulence model, 3-D numerical model and experiment setup are introduced. Then, the hydrogen behaviors with the GASFLOW-MPI including the light gas release, stratification and dissolution are analyzed and validated with the experiment data. In addition, the velocity profiles, light gas concentrations, dimensionless numbers and temperature distributions are evaluated for the characteristics of the hydrogen behaviors. The results indicate that the calculation results agree well with the experiment data. Foremostly, the relative errors between the calculation results and experiment data during the phase of the dissolution of the light gas cloud are within 11.9%. Meanwhile, the relative errors of the time for the complete dissolution during the phase of the dissolution of the light gas cloud are within 5.0%. For the light gas release and stratification phase, the jet flow dominates as the Froude (Fr) number exceeds 10 during the time t = 600 s–800 s. Additionally, the time averaged centerline velocity and light gas concentration after the potential core region decay with a slop of 1/z which coincide with the theoretical jet limit. Lastly, the light gas concentrations and temperature distributions in all three phases are captured clearly with the GAFLOW-MPI. It demonstrates that the GASFLOW-MPI can accurately described the details of the related hydrogen behaviors in the accident and management process in the confined enclosure like the NPP. This paper can provide guidance for the numerical computation of the hydrogen safety issues in the confined space. 相似文献