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Recent development and application of thin-film thermoelectric cooler
Yuedong Yu, Wei Zhu, Xixia Kong, Yaling Wang, Pengcheng Zhu, Yuan Deng
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 492-503.
https://doi.org/10.1007/s11705-019-1829-9
Recently, the performance and fabrication of thin-film thermoelectric materials have been largely enhanced. Based on this enhancement, the thin-film thermoelectric cooler (TEC) is becoming a research hot topic, due to its high cooling flux and microchip level size. To fulfill a thin-film TEC, interfacial problems are unavoidable, as they may largely reduce the properties of a thin-film TEC. Moreover, the architecture of a thin-film TEC should also be properly designed. In this review, we introduced the enhancement of thermoelectric properties of (Bi,Sb)2 (Te,Se)3 solid solution materials by chemical vapor deposition, physical vapor deposition and electrodeposition. Then, the interfacial problems, including contact resistance, interfacial diffusion and thermal contact resistance, were discussed. Furthermore, the design, fabrication, as well as the performance of thin-film TECs were summarized.
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A review on co-pyrolysis of coal and oil shale to produce coke
Xiangchun Liu, Ping Cui, Qiang Ling, Zhigang Zhao, Ruilun Xie
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 504-512.
https://doi.org/10.1007/s11705-019-1850-z
It has become the top priority for coking industry to rationally use and enlarge coking coal resources because of the shortage of the resources. This review focuses on the potential utilization of oil shale (OS) as a feedstock for coal-blending coking, in which the initial and basic step is pyrolysis. However, OS has a high ash content. If such OS is directly used for coal-blending coking, the coke product will not meet market demand. Therefore, this review firstly summarizes separation and beneficiation techniques for organic matter in OS, and provides an overview on coal and OS pyrolysis through several viewpoints (e.g., pyrolysis process, phenomena, and products). Then the exploratory studies on co-pyrolysis of coal with OS, including co-pyrolysis phenomena and process mechanism, are discussed. Finally, co-pyrolysis of different ranks of coals with OS in terms of coal-blending coking, where further research deserves to be performed, is suggested.
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Preparation and investigation of Pd doped Cu catalysts for selective hydrogenation of acetylene
Xinxiang Cao, Tengteng Lyu, Wentao Xie, Arash Mirjalili, Adelaide Bradicich, Ricky Huitema, Ben W.-L. Jang, Jong K. Keum, Karren More, Changjun Liu, Xiaoliang Yan
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 522-533.
https://doi.org/10.1007/s11705-019-1822-3
A series of PdCu bimetallic catalysts with low Cu and Pd loadings and different Cu: Pd atomic ratios were prepared by conventionally sequential impregnation (CSI) and modified sequential impregnation (MSI) of Cu and Pd for selective hydrogenation of acetylene. Characterization indicates that the supported copper (II) nitrate in the PdCu bimetallic catalysts prepared by MSI can be directly reduced to Cu metal particles due to the hydrogen spillover from Pd to Cu(NO3 )2 crystals. In addition, for the catalysts prepared by MSI, Pd atoms can form PdCu alloy on the surface of metal particles, however, for the catalysts prepared by CSI, Pd tends to migrate and exist below the surface layer of Cu. Reaction results indicate that compared with CSI, the MSI method enables samples to possess preferable stability as well as comparable reaction activity. This should be due to the MSI method in favor of the formation of PdCu alloy on the surface of metal particles. Moreover, even Pd loading is super low, <0.045 wt-% in this study, by through adjusting Cu loading to an appropriate value, attractive reactivity and selectivity still can be achieved.
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Catalytic combustion of methane over a highly active and stable NiO/CeO2 catalyst
Xiuhui Huang, Junfeng Li, Jun Wang, Zeqiu Li, Jiayin Xu
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 534-545.
https://doi.org/10.1007/s11705-019-1821-4
In the last decades, many reports dealing with technology for the catalytic combustion of methane (CH4 ) have been published. Recently, attention has increasingly focused on the synthesis and catalytic activity of nickel oxides. In this paper, a NiO/CeO2 catalyst with high catalytic performance in methane combustion was synthesized via a facile impregnation method, and its catalytic activity, stability, and water-resistance during CH4 combustion were investigated. X-ray diffraction, low-temperature N2 adsorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, hydrogen temperature programmed reduction, methane temperature programmed surface reaction, Raman spectroscopy, electron paramagnetic resonance, and transmission electron microscope characterization of the catalyst were conducted to determine the origin of its high catalytic activity and stability in detail. The incorporation of NiO was found to enhance the concentration of oxygen vacancies, as well as the activity and amount of surface oxygen. As a result, the mobility of bulk oxygen in CeO2 was increased. The presence of CeO2 prevented the aggregation of NiO, enhanced reduction by NiO, and provided more oxygen species for the combustion of CH4 . The results of a kinetics study indicated that the reaction order was about 1.07 for CH4 and about 0.10 for O2 over the NiO/CeO2 catalyst.
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Catalytic oxidative desulfurization of gasoline using phosphotungstic acid supported on MWW zeolite
Hanlu Wang, Idris Jibrin, Xingye Zeng
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 546-560.
https://doi.org/10.1007/s11705-019-1842-z
Catalysts for the desulfurization of gasoline samples were synthesized via the immobilization of well-dispersed phosphotungstic acid (HPW) on Mobil composition of matter-twenty-two (MWW) zeolite. Characterization results indicated that these catalysts possess a mesoporous structure with the retention of the Keggin structure of immobilized HPW. Relevant reaction parameters influencing sulfur removal were systematically investigated, including HPW loading, catalyst dosage, temperature, initial S-concentration, molar ratio of oxidant to sulfide (O/S), volume ratio of MeCN to model oil (Ext./oil), and sulfide species. The 40 wt-% HPW/MWW catalyst exhibited the highest catalytic activity with 99.6% dibenzothiophene sulfur removal from prepared samples. The 40 wt-% HPW/MWW catalyst was recycled four times and could be easily regenerated. Finally, as an exploratory study, straight-run-gasoline and fluid catalytic cracking gasoline were employed to accurately evaluate the desulfurization performance of 40 wt-% HPW/MWW. Our research provides new insights into the development and application of catalysts for desulfurization of gasoline.
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Morphology selective construction of β -cyclodextrin functionalized Fe3 O4 -Bi2 WO6 nanocomposite with superior adsorptivity and visible-light-driven catalytic activity
Maher Darwish, Ali Mohammadi, Navid Assi, Samer Abuzerr, Youssef Alahmad
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 561-578.
https://doi.org/10.1007/s11705-019-1808-1
Controlled growth of Bi2 WO6 nanorods with exposed [0 0 1] facets and the fabrication of an Fe3 O4 -Bi2 WO6 magnetic composite by a microwave-assisted polyol process, were achieved in this study. The adsorptivity and photocatalytic performance of the composite toward sunset yellow dye degradation were greatly enhanced by the β -cyclodextrin cavities on its surface, firmly anchored through a cetyltrimethylammonium bromide linkage. A series of examinations and characterizations were carried out to determine the influence of various factors on the morphological modulation-photocatalytic behavior of the pure Bi2 WO6 prior to final functionalization. Changing the pH of the precursor solution impacted the formation of 0D, 2D, and 3D structures; however, the presence of hexamethylenetetramine surfactant induced the development of 1D nanorod structure. A reasonable crystal growth mechanism was proposed to elucidate the formation process. Conversely, the mechanism of the activity enhancement of β -cyclodextrin functionalized Fe3 O4 -Bi2 WO6 , compared to that of the non-functionalized samples, could be realized with the assistance of chemical trapping experiments on sunset yellow, and was confirmed on the colorless antibiotic (sulfamethoxazole). The high performance and durability of this composite can be attributed to the facet-dependent activity, large adsorption capacity due to inclusion interactions, enhanced visible light absorption, and efficient charge separation.
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One-step synthesis of recoverable CuCo2 S4 anode material for high-performance Li-ion batteries
Tongzhou Lu, Yongzheng Zhang, Chun Cheng, Yanbin Wang, Yongming Zhu
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 595-604.
https://doi.org/10.1007/s11705-019-1818-z
A facile one-step hydrothermal method has been adopted to directly synthesize the CuCo2 S4 material on the surface of Ni foam. Due to the relatively large specific surface area and wide pore size distribution, the CuCo2 S4 material not only effectively increases the reactive area, but also accommodates more side reaction products to avoid the difficulty of mass transfer. When evaluated as anode for Li-ion batteries, the CuCo2 S4 material exhibits excellent electrochemical performance including high discharge capacity, outstanding cyclic stability and good rate performance. At the current density of 200 mA·g−1 , the CuCo2 S4 material shows an extremely high initial discharge capacity of 2510 mAh·g−1 , and the cycle numbers of the material even reach 83 times when the discharge capacity is reduced to 500 mAh·g−1 . Furthermore, the discharge capacity can reach 269 mAh·g−1 at a current of 2000 mA·g−1 . More importantly, when the current density comes back to 200 mA·g−1 , the discharge capacity could be recovered to 1436 mAh·g−1 , suggesting an excellent capacity recovery characteristics.
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Ball milling promoted direct liquefaction of lignocellulosic biomass in supercritical ethanol
Chunyan Yang, Xiaoliang Yuan, Xueting Wang, Kejing Wu, Yingying Liu, Changjun Liu, Houfang Lu, Bin Liang
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 605-613.
https://doi.org/10.1007/s11705-019-1841-0
In the present work, ball milling was applied for the pretreatment of lignocellulose to obtain high conversion and bio-oil yield in supercritical ethanol. Ball milling substantially decreased the crystallinity and particle size of lignocellulose, thereby improving its accessibility in ethanol solvent. An increased bio-oil yield of 59.2% was obtained for the ball milled camphorwood sawdust at 300°C, compared with 39.6% for the original lignocellulose. Decreased crystallinity significantly benefited the conversion of the cellulose component from 60.8% to 91.7%, and decreased particle size was beneficial for the conversion of all components. The obtained bio-oil had a high phenolic content, as analyzed by gas chromatography-mass spectrometry. Methoxylation and retro-aldol condensation were observed during alcoholysis, and the reaction pathways of lignocellulose in supercritical ethanol were attributed to the action of free radicals.
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Electrochemical sensor investigation of carbon-supported PdCoAg multimetal catalysts using sugar-containing beverages
Firat Salman, Hilal C. Kazici, Hilal Kivrak
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 629-638.
https://doi.org/10.1007/s11705-019-1840-1
Novel PdCoAg/C nanostructures were successfully synthesized by the polyol method in order to develop electrocatalysts, related to the glucose sensor performance of the high glycemic index in beverages. The characterization of this novel PdCoAg/C electrocatalyst was performed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy equipped with energy dispersive X-ray. The characterization results revealed that electronic state of the PdCoAg/C electrocatalyst was modified by the addition of the third metal. The electrochemical performances of the sensor were investigated by cyclic voltammetry and differential pulse voltammetry. The prepared enzyme-free sensor exhibited excellent catalytic activity against glucose with a wide detection range (0.005 to 0.35 mmol∙L−1 ), low limit of detection (0.003 mmol∙L−1 ), high sensitivity (4156.34 µA∙mmol−1 ∙L∙cm−2 ), and long-term stability (10 days) because of the synergistic effect between the ternary metals. The glucose contents of several energy drinks, fruit juices, and carbonated beverages were analyzed using the novel PdCoAg/NGCE/C sensor system. These results indicate the feasibility for applications in the foods industry.
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Investigation of solution chemistry to enable efficient lithium recovery from low-concentration lithium-containing wastewater
Chunlong Zhao, Mingming He, Hongbin Cao, Xiaohong Zheng, Wenfang Gao, Yong Sun, He Zhao, Dalong Liu, Yanling Zhang, Zhi Sun
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 639-650.
https://doi.org/10.1007/s11705-019-1806-3
In the production of lithium-ion batteries (LIBs) and recycling of spent LIBs, a large amount of low-concentration lithium-containing wastewater (LCW) is generated. The recovery of Li from this medium has attracted significant global attention from both the environmental and economic perspectives. To achieve effective Li recycling, the features of impurity removal and the interactions among different ions must be understood. However, it is generally difficult to ensure highly efficient removal of impurity ions while retaining Li in the solution for further recovery. In this study, the removal of typical impurity ions from LCW and the interactions between these species were systematically investigated from the thermodynamic and kinetics aspects. It was found that the main impurities (e.g., Fe3+ , Al3+ , Ca2+ , and Mg2+ ) could be efficiently removed with high Li recovery by controlling the ionic strength of the solution. The mechanisms of Fe3+ , Al3+ , Ca2+ , and Mg2+ removal were investigated to identify the controlling steps and reaction kinetics. It was found that the precipitates are formed by a zero-order reaction, and the activation energies tend to be low with a sequence of fast chemical reactions that reach equilibrium very quickly. Moreover, this study focused on Li loss during removal of the impurities, and the corresponding removal rates of Fe3+ , Al3+ , Ca2+ , and Mg2+ were found to be 99.8%, 99.5%, 99%, and 99.7%, respectively. Consequently, high-purity Li3 PO4 was obtained via one-step precipitation. Thus, this research demonstrates a potential route for the effective recovery of Li from low-concentration LCW and for the appropriate treatment of acidic LCW.
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Flow synthesis of a novel zirconium-based UiO-66 nanofiltration membrane and its performance in the removal of p -nitrophenol from water
Feichao Wu, Yanling Wang, Xiongfu Zhang
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 651-660.
https://doi.org/10.1007/s11705-019-1819-y
In this work, a thin zirconium-based UiO-66 membrane was successfully prepared on an alumina hollow fiber tube by flow synthesis, and was used in an attempt to remove p -nitrophenol from water through a nanofiltration process. Two main factors, including flow rate and synthesis time, were investigated to optimize the conditions for membrane growth. Under optimal synthesis conditions, a thin UiO-66 membrane of approximately 2 µm in thickness was fabricated at a flow rate of 4 mL·h−1 for 30 h. The p -nitrophenol rejection rate for the as-prepared UiO-66 membrane applied in the removal of p -nitrophenol from water was only 78.1% due to the existence of membrane defects caused by coordinative defects during membrane formation. Post-synthetic modification of the UiO-66 membrane was carried out using organic linkers with the same flow approach to further improve the nanofiltration performance. The result showed that the p -nitrophenol rejection for the post-modified membrane was greatly improved and reached over 95%. Moreover, the post-modified UiO-66 membrane exhibited remarkable long-term operational stability, which is vital for practical application.
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Enhanced desulfurization performance of hybrid membranes using embedded hierarchical porous SBA-15
Ye Zhang, Jian Song, Josue Quispe Mayta, Fusheng Pan, Xue Gao, Mei Li, Yimeng Song, Meidi Wang, Xingzhong Cao, Zhongyi Jiang
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 661-672.
https://doi.org/10.1007/s11705-019-1830-3
The utilization of materials with a hierarchical porous structure as multi-functional additives is highly attractive in the preparation of hybrid membranes. In this study, novel hybrid membranes are designed by embedding hierarchical porous Santa Barbara Amorphous 15 (SBA-15) with a dual-pore architecture (micropores and mesopores) for pervaporation desulfurization. The SBA-15 with cylindrical mesopores provides molecular transport expressways to ensure improved permeability, while micropores on the wall have molecular sieving effects that are essential for the enhancement of permselectivity of thiophene molecules. Considering thiophene/n -octane mixture as a model system, the hybrid membrane with embedded 6 wt-% SBA-15 exhibits optimal pervaporation desulfurization performance with a permeation flux of 22.07 kg·m−2 ·h−1 and an enrichment factor of 6.76. Moreover, the detailed structure and properties of hybrid membranes are systematically characterized. This study demonstrates the immense potential of hierarchical porous materials as additives in membranes to simultaneously increase permeability and permselectivity.
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Preparation of adsorptive nanoporous membrane using powder activated carbon: Isotherm and thermodynamic studies
Majid Peyravi
Front. Chem. Sci. Eng.. 2020, 14 (4 ): 673-687.
https://doi.org/10.1007/s11705-019-1800-9
Adsorptive polyethesulfone (PES) membranes were prepared by intercalation of powder activated carbon (PAC) with and without functionalization. Accordingly, PAC was aminated with 1,5-diamino-2-methylpentane, and the physicochemical properties of the functionalized PAC were analyzed. Intercalation of PAC within the PES scaffold changed the porosity and mean pore size of the aminated membrane (AC-NH2 ) from 52.6% to 92.5% and from 22.6 nm to 3.5 nm, respectively. The effect of temperature on the performance of the modified membranes was monitored by the flux and chemical oxygen demand (COD) removal of leachate. At ambient temperature, the COD removal of the neat, AC-containing, and AC-NH2 membranes was 47%, 52%, and 58.5%, respectively. A similar increment was obtained for the membrane flux, which was due to the synergistic effect of the high porosity and large number of hydrophilic functional groups. The experimental leachate adsorption data were analyzed by Langmuir, Freundlich, and Dubinin- Radushkevich isotherm models. For all membranes, the significant thermodynamic parameters (ΔH , ΔS , and ΔG ) were calculated and compared. The isosteric heat of adsorption was lower than 80 kJ∙mol− 1 , indicating that the interaction between the membranes and the leachate is mainly physical, involving weak van der Waals forces.
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