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Table of Content

    30 March 2022, Volume 24 Issue 1
    Content
    2022, 24(1):  1-02. 
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    Content
    Scientific Research
    Heteroatom-doped carbon Spheres from Fluidized Catalytic Cracking Slurry Oil as anode material for lithium-ion battery
    2022, 24(1):  1-10. 
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    A facile injected pyrolysis strategy to synthesize heteroatom-doped carbon spheres (CSs) with good conductivity is proposed by only using fluidized catalytic cracking slurry oil (FCCSO) as carbon source through a pyrolysis reaction process at 700-1000°C. The structures of CSs are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The influence of preparation conditions on the morphology of CSs and its electrochemical properties as anode material for Lithium-ion battery (LIBs) are investigated. The XPS measurement results show that the CSs mainly contain C, N, O and S elements. With the increase of pyrolysis temperature, the particle size of CSs decreases but the graphitization degree of CSs increases. As the anode material for lithium-ion batteries (LIBs), CSs shows excellent electrochemical performance with a high maximum reversible capacity of 365 mAh·g-1 and an initial coulombic efficiency of 73.8% at a low current density of 50 mA·g-1. CSs exhibits excellent cycling stability in the current range of 50 mA·g-1 to 2 A·g-1 and still maintains a stable reversible capacity of 347 mAh·g-1 when the current is cycled back to 50 mA·g-1. This is mainly due to the existence of suitable heteroatom content and unique spherical structure of CSs. The heteroatom-doped CSs provides a new choice for the preparation of high efficiency anode materials for LIBs.
    Study on viscosity reducing and oil displacement agent for water-flooding heavy oil reservoir
    2022, 24(1):  11-18. 
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    In the process of water-flooding development of heavy oil reservoir, due to the high viscosity and oil-water mobility ratio of heavy oil, there are some problems such as poor fluidity, high residual oil saturation and low recovery efficiency, which seriously restrict the efficient development of heavy oil. The molecular structure characteristics of asphaltene and resin in heavy oil were analyzed. Based on the three most concerned properties of chemical agents, including emulsification performance, interface performance and oil washing performance, three chemical oil displacement agents for heavy oil reservoirs were developed, and the structure of the chemical agents were characterized by high resolution mass spectrometry. The performance evaluation of chemical agent and core displacement experiment show that there is no obvious correlation between the properties of chemical agents, including interfacial tension, emulsifying ability and oil washing ability. For heavy oil reservoirs, the emulsification and viscosity reduction performance of chemical agents was more important than oil washing capacity, and oil washing capacity was more important than interface performance. Viscosity reduction performance was the key parameter of oil displacement agent suitable for heavy oil reservoir. The composite binary system of viscosity reducer and polymer had better oil recovery than using viscosity reducer alone.
    Electrospinning nanofiber membrane reinforced PVA composite hydrogel with preferable mechanical performance for oil-water separation
    cheng zhilin
    2022, 24(1):  19-26. 
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    Nowadays hydrogels have been attracting the massive interest in oil-water separation due to their robust hydrophilicity and fantastic underwater oiliness features. However, the weak toughness and tensile strength shortcomings of hydrogels have thus inhibited their actual applicability. For this reason, we successfully fabricated the electrospun nanofiber membrane-reinforced PVA composite hydrogels. The PVA-PAN composite hydrogel has exhibited the excellent tensile strength and friction performance, separately enhancing 174.2% of the tensile strength, and reducing 20.7% of the friction coefficient and 58.7% of wear volume relative to the neat PVA hydrogel. Furthermore, the pull-out experiments indicated that the PAN nanofiber membrane exerted a stronger interface bonding effect with PVA hydrogel. The oil-water separation evaluation test showed that the separation efficiency reached up to 97.6% for treating the SA-100 lubricating oil/water system.
    Role of heating condition in polyethylene behaviors under nitrogen and air atmosphere
    2022, 24(1):  27-35. 
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    Recycle of plastic waste is an indisputable means to alleviate both environment and energy crisis. In this work, effects of heating condition on polyethylene behaviors in nitrogen and air were studied. It was observed that polyethylene behavior was a single step in nitrogen, while the multiple steps occurred in air. According to the weight loss and heat flow curves, polyethylene behaviors in air were divided into three regions: low-temperature (<340 °C), middle-temperature (340—380 °C) and high-temperature (> 380 °C) regions. Kinetic analysis revealed that the partial oxidization took the dominance in the low-temperature region, which seldom formed CO and CO2; the combustion took the dominance in the middle-temperature region, which was positive to the formation of CO and CO2; the pyrolysis was initiated and enhanced in the high-temperature region, which inhibited the formation of CO and CO2. According to the kinetic simulation, a synergistic effect between the pyrolysis and combustion was proposed to account for the acceleration of polyethylene conversion. This work may provide useful information about polyethylene behaviors under heating condition, and help to design and optimize plastic waste incineration process.
    Study on the low-temperature properties of the asphalt modified by carbon nanotubes (CNTs) and crumb rubber (CR)
    2022, 24(1):  36-47. 
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    The effect of adding crumb rubber (CR) and carbon nanotubes (CNTs) on the low-temperature properties of virgin asphalt was studied. Using the force-ductility test and the bending beam rheometer (BBR) test, the deformation resistance and rheological properties of asphalt samples at low temperatures were evaluated, respectively. Based on the result of BBR test, the creep functions of the Burgers model and the Zener model were used to fit the low-temperature creep characteristics of the asphalt samples. Furthermore, the differential scanning calorimetry (DSC) test and the attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) test were utilized to appraise the low-temperature stability and chemical properties of asphalt samples, respectively. The results showed that CR significantly improved the lowtemperature properties of virgin asphalt, while CNTs had little effect. Moreover, during the degradation of CR, aromatic and aliphatic components were released. In particular, the aliphatic components of CR-modified asphalt were much higher than those of virgin asphalt, which had a significant effect on improving the low-temperature properties of the asphalt. The DSC test results showed that CR enhanced the low-temperature stability of the asphalt, while the addition of CNTs presented a slightly negative effect.
    Application of GC-qqqMS/MS in Gasoline Models and Regions Identification
    2022, 24(1):  48-58. 
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    Based on GC-qqqMS/MS, a qualitative and quantitative analysis method for characteristic markers in gasolines was established. According to the established method, different models (92#, 95#, 98#) and regions (south, central, northeast, northwest China) of gasoline were studied and analyzed. The results show that the gasolines can be classified by the relative contents of aromatics, naphthalene series, indene and other characteristic substances. On the basis of the high sensitivity and selectivity of GC-qqqMS/MS, the experiment has identified the characteristic substances, and used characteristic-ratios methods and stoichiometric tools to achieve the models and regional differences of gasolines. It is conducive to the identification and classification of ILR in public security in fire cases, and meets the actual handling demand.
    Assembling Fe2O3/BiOCl Composite for Highly Effective Degradation of Water Pollutants under Visible-Light Irradiation
    Liu Xiaoqing
    2022, 24(1):  59-67. 
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    Fe2O3 was synthesized by the solvothermal method, and the synthesized Fe2O3 was added in the process of preparing BiOCl by hydrolysis, and then Fe2O3/BiOCl photocatalytic materials with different composite ratios were prepared. The optimal Fe2O3/BiOCl (1Fe/50Bi) sample showed a highest photocatalytic efficiency for cationic dyes (Rhodamine B) and anionic dye (methyl orange) degradation irradiated with visible light, as compared with that of a bare BiOCl catalyst. Meanwhile, radical capturing experiments indicated that the photo-induced holes (h+) is the main active species. X-ray powder diffraction and ultraviolet-visible diffuse reflectance spectroscopy were used to characterize the structural and optical properties, which proved that Fe2O3 was successfully composited to the BiOCl surface and effectively reduced the bandgap of BiOCl. More importantly, the optimal 1Fe/50Bi sample shows the highest photocatalytic efficiency for tetracycline (TC) degradation (98%) irradiated with visible light, as compared with that of a bare BiOCl catalyst. Consequently, the Fe2O3/BiOCl photocatalyst have potential applications in environmental purification.
    A novel MIL-101(Cr) acidified by silicotungstic acid and its catalytic performance for isomerization of n-heptane
    2022, 24(1):  68-80. 
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    0.4%Pt/xSTA-MIL-101(Cr) metal-acid bifunctional catalysts were prepared by impregnation using STA-MIL-101(Cr) as the support. The synthesized samples were verified to exhibit a typical octahedral structure of MIL-101(Cr) and the pore structure were arranged orderly. The specific surface area of the samples was extremely high and the samples were micro-mesoporous composite materials. Silicotungstic acid could retain its Keggin structure in the 0.4%Pt/xSTA-MIL-101(Cr) samples and the catalyst possessed moderately strong Br?nsted acid sites. Besides, the dispersion of Pt particles in MIL-101(Cr) was relatively high. n-Heptane isomerization was first used as a probe to test the novel 0.4%Pt/xSTA-MIL-10(Cr) catalyst. Compared with the conventional silicate catalysts, the catalytic performance of 0.4%Pt/30wt%STA-MIL-101(Cr) was significantly improved with n-heptane conversion of 58.93% and iso-heptane selectivity of 95.68%, respectively, when the reaction time was 2 h at the reaction temperature of 260 oC. The catalyst could still maintain a relatively high catalytic performance during the reaction time of 5 h. Compared with the non-noble metal catalysts, the catalytic efficiency is relatively high. The mechanism model of n-heptane isomerization over 0.4%Pt/xSTA-MIL-101(Cr) catalyst was established.
    One-step Synthesis and Photocatalytic Degradation Performance of Sulfur-doped Porous g-C3N4 nanosheets
    2022, 24(1):  81-89. 
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    Abstract: In this study, sulfur-doped porous g-C3N4 nanosheets (CN-T-U 1.75) have been synthesized successfully by one-step calcination using urea and thiourea as the precursors. CN-T-U 1.75 exhibited excellent photocatalytic performance for Rhodamine B (RhB) degradation under visible light irradiation, with the kinetic reaction rate constant of 0.01838 min-1. Analysis of the characterization results showed that CN-T-U 1.75 had a larger specific surface area, and the doping caused a change in the energy band structure. Moreover, the catalytic mechanism analysis shows it could produce two oxidation groups of ?O2- and ?OH to degrade pollutants synergistically.
    Process Research
    Effect of polycyclic aromatic hydrocarbons on the stability of the catalyst for the production of diesel with ultra-low sulfur content
    Ding Shi Pan-Zhu GE Zhang Rui Xi Yuanbing Zhang Le Li Dadong Nie Hong
    2022, 24(1):  90-99. 
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    The effect of polycyclic aromatic hydrocarbons (PAHs) on the stability of the hydrogenation catalyst for production of ultra-low sulfur diesel was studied in a pilot plant using Ni-Mo-W/γ-Al2O3 catalyst. The mechanisms of catalyst deactivation were analyzed by the methods of elemental analysis, nitrogen adsorption-desorption, thermogravimetry-mass spectrometry (TG-MS) technology, X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM). The results demonstrated that PAHs had little effect on the activity of catalyst at the beginning of operation, during which the reaction temperature was increased by only 1 — 4 ℃. However, the existence of PAHs significantly accelerated the deactivation of catalyst and weakened the stability of catalyst. This phenomenon could be explained by that the catalyst deactivation is not only related to the formation of carbon deposit, but also is closely related to the loss of pore volume and the decrease of Ni-W-S phase ratio after adding PAHs.
    Preparation of solid waste-based activated carbon and its adsorption mechanism for toluene
    2022, 24(1):  100-110. 
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    Regenerated activated carbon (RAC) samples were prepared by carbon activation using waste activated carbon from solid waste resources as the carbon source precursor, adding alkaline additives, and further modified by potassium ferrate to finally prepare high-performance VOCs adsorption carbon. At the same time, the samples before and after modification were systematically studied through characterization equipment such as SEM, RAMAN, FT-IR, XPS, and dynamic/static adsorption. The results showed that the specific surface area and pore volume of the RAC after modification by the strong oxidant potassium ferrate increased by 1.4 times; the degree of defects was enhanced and the content of oxygen-containing functional groups on the surface increased significantly. Among them, the sample modified with potassium ferrate for 24h had the best toluene dynamic adsorption performance (375.5 mg/g), and the dynamic adsorption capacity was twice that of the original sample (192.8 mg/g); The static adsorption test found that the maximum adsorption capacity of RAC-6%K2FeO4+H2SO4-24h was 796 mg/g, which indicated that potassium ferrate modification treatment can significantly increase the VOCs adsorption performance of RAC. In addition, through consecutive toluene adsorption-desorption cycle tests, it was found that the sample RAC-6%K2FeO4+H2SO4-24h still maintained 91% adsorption activity after the fifth regeneration. This indicates that RAC-6%K2FeO4+H2SO4-24h has good cycle stability and great application value for the efficient purification of industrial VOCs waste gas.
    Influence Factors Analysis of FCC Slurry Separation by Mixed Solvent Extraction
    Yu-dong SUN
    2022, 24(1):  111-116. 
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    The influence of solvent formulation, temperature, time and solvent-oil ratio on extract oil yields and aromatics contents were analyzed by four factors and three levels of orthorhombic method with Daqing FCC slurry as feedstock and extraction solvent preparing by N,N-dimethylformamide and anti-extractant. The regressive model of extract oil yields and aromatics contents to solvent formulation, temperature, time and solvent-oil ratio were established. The analysis result by response surface method showed that solvent formulation, temperature and solvent-oil ratio have obvious effect on extraction results and there was interaction between temperature and solvent-oil ratio on aromatics contents when FCC slurry extracted by mixed solvent, but the effect of time was not obvious. The model analysis showed that the optimality conditions for FCC slurry separation by mixed solvent were 2.3 of DMF/ anti-extractant, 62.8℃ of temperature, 3.2 of solvent-oil ratio and 35min of time. The prediction results was well consistent with the verification test.
    Antibacterial and Corrosion Inhibition Properties of SA-ZnO@ODA-GO@PU Super-Hydrophobic Coating in Circulating Cooling Water System
    2022, 24(1):  117-128. 
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    In order to solve corrosion problem of circulating cooling water system, SA-ZnO@ ODA-GO@ PU super-hydrophobic coating was synthesized for pipeline protection. After hydrophobic modification, the contact angle (CA) of the coating was above 150o. The coating antibacterial ability was essential for corrosion protection. SA-ZnO@ODA-GO can seriously damage the cell structure, make the cell content outflow, increase the leakage rate of protein, and make the bacteria unable to reach logarithmic growth phase within 24 h. The corrosion inhibition mechanism analysis of SA-ZnO@ODA-GO@PU coating indicated that the hydrophobic modified coating formed a physical barrier to prevent water molecules from entering the carbon steel. On the surface of the specimen, the coating prevented charge transfer.
    Investigation of nitrite production pathway in integrated partial denitrification/anammox process via isotope labelling technique and the relevant microbial communities
    Yan-Zhe LI Zhao Dongfeng Guo Yadong Zhao Chaocheng Liu Fang Liu Chunshuang
    2022, 24(1):  129-134. 
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    In this study, the nitrogen removal performance of PDA process was investigated by using UASB reactor. High TN removal efficiency (91.97%) was achieved at influent nitrogen loading rate of 0.64 kg/m3d. Anammox bacteria did execute the function of converting nitrate to nitrite in PDA system according to 15N isotope labeling experiments and the contribution was approximately 36.3%. Candidatus_Brocadia, Candidatus_Kuenenia and Thauera were functional strains for anammox and denitrification process, respectively. Thauera and Candidatus_Brocadia were more important for TN removal at high loading rates (0.64 kg/m3d). This result provides a theoretical and technical foundation for the application of denitrifying ammonium oxidation process.
    Simulation and Optimization
    Hydrodynamic Instability Analysis of the Axial Flow Pump in an Ethylene Polymerization Loop Reactor
    Jin Lu yang yao Jing-Yuan Sun Huang Zhengliang Yang Yongrong Wang Jingdai
    2022, 24(1):  135-148. 
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    The hydrodynamic instability of the axial flow pump in a loop reactor has long been a troubling issue to be solved in the polyethylene industry due to the lack of a better mechanismic understanding. Generally, the instability of an axial flow pump can be reflected by the fluctuation of the pump head. In this study, the transient computational fluid dynamics (CFD) simulation is adopted to study the hydrodynamic instability of the axial flow pump used in an ethylene polymerization loop reactor. The results show that the pump head under single liquid phase nearly remains constant while the pump head under slurry phase fluctuates due to the variation of solid volume fraction distribution in the pump. Besides, under the combined effect of the maximum solid volume fraction difference in the pump and the turbulence intensity of the liquid phase, the fluctuation of the pump head under slurry phase increases when the solid volume fraction in the loop reactor increases from 0.10 to 0.29, while the fluctuation decreases, with the solid volume fraction increasing from 0.29 to 0.35. Furthermore, there is a negative correlation between the pump head and the solid volume fraction in the pump; with the increase of solid volume fraction in the loop reactor, the correlation coefficient increases as well. Moreover, a ‘spiral particulate band’ phenomenon is formed in the ascending leg caused by three mechanisms, viz.: the segregation of particles in all bends, the dispersion of particles by the secondary flow in the ascending leg, and the rotational movement of particles in the pump.
    Review
    Photocatalysts for photocatalytic CO2 reduction:A review
    Lizhong Zhang
    2022, 24(1):  149-160. 
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    Energy crisis and environmental pollution have become vitally severe challenges for the current society. During the circumstances of pursuing carbon peak and carbon neutrality, photocatalytic CO2 reduction will be an essential, necessary and even inevitable development requirement and trend. However, there are some bottlenecks that need to be addressed immediately, such as low quantum efficiency and narrow light absorption range for single photocatalysts. Therefore, efficient and stable visible light driving materials are the core challenge in the field of photocatalytic CO2 conversion. This paper reviewed the photocatalysts used for CO2 reduction classified as metal photocatalysts, non-metal photocatalysts, and MOFs photocatalysts, and the CO2 reduction capacity and mechanism of different photocatalysts were described. In the end, the problems to be solved and the future development of photocatalytic CO2 reduction were summarized.