Institutional Repository of Institute of Process Engineering, CAS (IPE-IR）
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Role of carbon-oxygen complexes on low temperature reduction of NO by coal char
No full textThe reduction of NO by Shenmu coal char was studied at 450, and the relationship between the influencing factors of coal char denitrification and its surface carbon-oxygen functional groups was explored by Raman, FT-IR, XPS and other analytical methods. Combining the results of isothermal experiments and characterizations, close connection between influencing factors and carbon-oxygen complexes was revealed. The effect of coal char preparation temperature, oxygen concentration in flue gas as well as influence of metallic elements could be in connection with carbon-oxygen complexes on coal char surface. More specifically, lowering pyrolysis temperature, increasing oxygen concentration, and loading metals were all conducive to the retention and formation of thermally stable C-O species on coal char surface. Strong linear relationship was discovered via XPS method between thermally stable C-O species and experimental evaluation indexes (R2>0.96). Carbon-oxygen complexes, especially thermally stable C-O compounds, played a key character in NO reduction by coal char. 漏 2022, Editorial Board of CIESC Journal. All right reserved
Iron removal and titanium dioxide support recovery from spent V2O5-WO3/TiO2 catalyst
No full textIron seriously affects the quality of TiO2 support recovered from spent selective catalytic reduction (SCR) catalyst. In this paper, the iron removal and TiO2 support recovery from spent SCR catalyst were studied. The experiment results suggested that iron exists on the surface and bulk structure of a spent SCR catalyst. The iron deposited on the surface of the spent SCR catalyst was removed by ultrasonic cleaning. The iron remaining in the bulk structure of the spent SCR catalyst was primarily Fe(III) and was adequately removed by NaOH activation and acid washing. The NaOH activation process considerably increased the specific surface area of the spent SCR catalyst. Subsequently, iron was efficiently dissolved through the synergistic effect of sulfuric acid and ascorbic acid. Sulfuric acid dissolved iron in the form of Fe3+, and ascorbic acid promoted iron dissolution by reducing Fe3+ to Fe2+. After the recovery process, 97.1% of the iron in the spent SCR catalyst was removed, and anatase TiO2 was recovered from the spent SCR catalyst. The recovered anatase TiO2 can be used as support material to produce fresh SCR catalyst. 漏 2022 Elsevier B.V
Recycling and utilization of calcium carbide slag - current status and new opportunities
No full textCoal is the dominant fuel in China to provide primary energy, and 70% of polyvinyl chloride is produced from coal-based CaC2. CaC2 reacts with water to produce acetylene and calcium carbide slag (CCS) as a solid waste for polyvinyl chloride production. Approximate 40 million tons of dry CCS are generated annually in China, among which only a small part is used in cement and as desulfurization agents. In contrast, most of the CCS is accumulated, occupying land and posing environmental risks. For the chlor-alkali industry, CCS can regenerate massive CaO through purification, molding, calcination. Thus, CCS can be used as raw material for CaC2 production, thereby realizing renewable and sustainable utilization of calcium resources. Therefore, the recycling of CCS decreases the need for limestone extraction, leading to reduced CO2 emission, energy consumption, and solid waste pollution. For example, if CaO is produced by CCS instead of natural limestone, 20 million tons of CO2 emissions can be reduced each year. While the massive CaO with high thermal strength is crucial for the CaC2 production in the electric arc furnace, enabling CCS recycling and sustainable utilization. 漏 2022 Elsevier Lt
Mg(NO3)2·6H2O-LiNO3 eutectic/expanded graphite composite phase change material for thermal energy storage applications
No full textA new eutectic mixture phase change material containing magnesium nitrate hexahydrate and lithium nitrate has been successfully prepared, which can be applied in the field of residential radiator heating due to the suitable phase change temperature and high latent heat. Further, by physical blending magnesium nitrate hexahydrate/lithium nitrate eutectic mixtures and expanded graphite, the new composites were prepared. The crystalline structure, thermal properties, corrosion performance of eutectic phase change materials were systematically measured. The results showed that the best eutectic mixtures had a phase change temperature of 72.35 掳C and latent heat of 170.32 kJ/kg, with a little supercooling degree. The thermal conductivity was effectively improved by adding expanded graphite. Meanwhile, corrosion tests suggested aluminum and stainless steel 304 could be the preferred choices as the container. Overall, the prepared eutectic composite materials with superior performances could be a promising candidate for the residential radiator heating field. 漏 2022 Elsevier Lt
The structure-activity relationship of aromatic compounds in advanced oxidation processesa review
No full textAdvanced oxidation processes (AOPs) are widely used as efficient technologies to treat highly toxic and harmful substances in wastewater. Taking the most representative aromatic compounds (monosubstituted benzenes, substituted phenols and heterocyclic compounds) as examples, this paper firstly introduces their structures and the structural descriptors studied in AOPs before, and the influence of structural differences in AOPs with different reactive oxygen species (ROS) on the degradation rate was discussed in detail. The structure-activity relationship of pollutants has been previously analyzed through quantitative structure-activity relationship (QSAR) model, in which ROS is a very important influencing factor. When electrophilic oxidative species attacks pollutants, aromatic compounds with electron donating groups are more favorable for degradation than aromatic compounds with electron donating groups. While nucleophilic oxidative species comes to the opposite conclusion. The choice of advanced oxidation processes, the synergistic effect of various active oxygen species and the used catalysts will also change the degradation mechanism. This makes the structure-dependent activity relationship uncertain, and different conclusions are obtained under the influence of various experimental factors. 漏 2022 Elsevier Lt
Research progress in nanofiber supported nano zero-valent-iron based materials in environmental remediation
No full textNano zero-valent-iron (nZVI) composites are associated with defects such as easy agglomeration and difficulty in separation and recovery, which lead to declined degradation efficiency and reduced service life. The preparation methods of nZVI and the latest research results of nZVI based materials in the field of soil and water pollution control were introduced. The reaction principle of nZVI to remove pollutants was discussed and analyzed. The preparation methods and pollutant removal effects of nanofiber supported nZVI based materials such as membranes made from polyacrylic acid/polyvinyl alcohol (PVA) composite nanofiber, chitosan composite nanofiber, polyaniline nanofiber and carbon nanofiber were summarized respectively. The progress review revealed that the carrier material in the form of electrospun nanofibers can effectively inhibit the agglomeration of nZVI, improve the separation and recovery performance and broaden the practical application scope. Nanofibers are shown as a new effective carrier to load nZVI based materials for environmental remediation. 漏 2022, Periodical Agency of Journal of Textile Research. All right reserved
Machine Learning Screening of Efficient Ionic Liquids for Targeted Cleavage of the 尾-O-4 Bond of Lignin
No full textLignin conversion into high value-added chemicals is of great significance for maximizing the use of renewable energy. Ionic liquids (ILs) have been widely used for targeted cleavage of the C-O bonds of lignin due to their high catalytic activity. Studying the cleavage activity of each IL is impossible and time-consuming, given the huge number of cations and anions. Currently, the mainstream approach to determining the cleavage activity of one IL is to calculate the activation barrier energy (Ea) theoretically via transition state search, a process that involves the iterative determination of an appropriate 'imaginary frequency'. Machine learning (ML) has been widely used for catalyst design and screening, enabling accurate mapping from specified descriptors to target properties. To avoid complicated Eacalculations and to screen potential candidates, in this study, we selected nearly 103ILs and guaiacylglycerol-尾-guaiacyl ether (GG) as the lignin model and used the ML technology to train models that can rapidly predict the cleavage activity of ILs. Taking the easily accessible bond dissociation energy (BDE) of the 尾-O-4 bond in GG as the target, an ML model with r > 0.93 for predicting the catalytic activity of ILs was obtained. The change tendency of the BDE is consistent with the experimental yield of guaiacol, reflecting the reliability of the ML model. Finally, [C2MIM][Tyrosine] and [C3MIM][Tyrosine] as the optimal candidates for future applications were screened out. This is a novel strategy for predicting the catalytic activity of ILs on lignin without the need to calculate complicated reaction pathways while reducing time consumption. It is anticipated that the ML model can be utilized in future practical applications for targeted cleavage of lignin. 漏 2022 American Chemical Society. All rights reserved
Numerical simulation of commercial MTO fluidized bed reactor with a coarse-grained discrete particle method EMMS-DPM
No full textParticle scale information of commercial fluidized beds is important for its design and optimization, e.g., the catalyst performance evolution along time. However, it is difficult to be obtained by in-situ measurements or continuum-based numerical simulations due to the limited accuracy in space and time. Thus, the newly developed reaction model for methanol-to-olefins (MTO) is integrated into the coarse-grained discrete particle method (EMMS-DPM) to study the evolution of coke content distribution on the catalyst. The main gaseous products of the commercial MTO reactor are well predicted. Then, the operation optimization for a commercial MTO reactor is conducted by changing the annual processing capacity and the size distribution of catalysts. Results show that the reactor operation is slightly more difficult when the annual processing capacity is increased by 20%, and increasing the mass fraction of finer catalyst may result in more homogeneous MTO reaction and reduce the energy consumption. 漏 2022 Elsevier B.V
Phosphorus containing layered quadruple hydroxide electrode materials on lab waste recycled flexible current collector
No full textFrom environmental waste to energy storage, waste boxes converted into conductive electrodes to further grow active materials has been an interesting way of upcycling. In this study, we transformed waste boxes of KIMTECH Kimwipes庐 into conductive f-MWCNTs light and flexible substrate (LFS) as current collectors. Then, undoped and P-doped active materials consisting of layered quadruple hydroxides (LQH) was successfully grown on the conductive f-MWCNTs/LFS. Specifically, P-doped f-MWCNTs/LQH demonstrates 1.8 times the capacitance of an undoped f-MWCNTs/LQH. Such conversion of waste boxes not only offers a useful way of reusing waste papers which commonly ends in landfills, but the inexpensive method also offers an extreme way of cutting cost in developing conductive substrates. Also, the effective strategy of synthesizing active materials on the conductive f-MWCNTs/LFS paves its way as potential cheap electrodes of the future generation. 漏 2021 Elsevier Inc
Nitrogen-doped carbon black supported synergistic palladium single atoms and nanoparticles for electrocatalytic oxidation of methanol
No full textFor commercially viable direct methanol fuel cells, electrocatalysts play a crucial role in motivating the sluggish methanol oxidation reaction (MOR) over anode. Unfortunately, the large-scale applications of current MOR catalysts are hampered by their poor tolerance to poisoning and fast activity degradation. Herein, a unique composite catalyst comprised of partial Pd nanoparticles and partial Pd single atoms (PdNPs/Pd-Nx@C) is developed. The as-fabricated catalyst exhibits remarkable activity of 9.45 mA路cm鈭? towards MOR in alkaline solution, which is 7.05 and 3.92 times that of commercial Pd/C and nanoparticle type (PdNPs@C) electrocatalysts, respectively. Impressively, the PdNPs/Pd-Nx@C shows the highest long-time stability with 90.38% and 89.8% of the initial activity retained after 3600 s chronoamperometry (CA) test and 2000 cycles of cyclic voltammetry (CV) measurements with accelerated durability test (ADT), respectively. Combined with high-angle annular darkfield scanning transmission electron microscopy (HAADF-STEM), X-ray adsorption fine structure (XAFS) spectra and X-ray photoelectron spectroscopy (XPS) analyses, the superior performance of PdNPs/Pd-Nx@C can be ascribed to the synergistic effect from the Pd single atoms, N-doped carbon supports and Pd nanoparticles. Notably, the embedded Pd single atoms are liable to transfer electrons to the substrate due to the electronic metal-support interactions (EMSI) and the charge transfer between Pd nanoparticles and carbon supports is suppressed, inducing a weak adsorption strength of poisonous carbonous intermediate species on active Pd nanoparticles and improved poisoning tolerance in MOR process, which is verified by density functional theory (DFT) calculations as well as CO-stripping voltammetry experiments. This work not only contributes the first example of a synergistic catalyst between nanoparticles and single atoms for MOR but also deepens the knowledge on the metal-support interaction. 漏 2022 Elsevier B.V