Microwave-Assisted Grafting of Coal onto Nitrogen-Doped Carbon Dots with a High Quantum Yield and Enhanced Photoluminescence Properties.

The fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized via a facile one-pot solvothermal process using coal (Jin 15 Anthracite and Shaerhu lignite) as raw materials and dimethyl formamide (DMF) as the solvent, employing a microwave pyrolysis method. This approach demonstrates remarkable efficacy in the development of nitrogen-doped carbon dots (N-CDs) with a high quantum yield (QY). The N-CDs prepared have strong photoluminescence properties. Moreover, the obtained N-CDs emit blue PL and are easily dispersed in polymethyl methacrylate (PMMA), preserving the inherent advantages of N-CDs and the PMMA matrix. The JN-CDs exhibit a high quantum yield (QY) of 49.5% and a production yield of 25.7%, respectively. In contrast, the SN-CDs demonstrate a quantum yield of 40% and a production yield of 35.1%. It is worth noting that the production yield and quantum yield of coal-based carbon dots are inversely related indices. The lower metamorphic degree of subbituminous coal favors an enhanced product yield, while the higher metamorphic degree of anthracite promotes an improved quantum yield in the product, which may be attributed to the presence of amorphous carbon within it. Consequently, we propose and discuss potential mechanisms underlying N-CD formation.

Characteristics of the Blockage from Air Nozzle Guide Duct in Circulating the Fluidized-Bed Coal Gasifier and Its Formation Mechanism.

Blockage is often generated in the air nozzle guide duct in a circulating fluidized-bed coal gasifier (CFBG), especially with Zhundong sub-bituminous coal (ZSBC) as the raw material. A typical example is found in one CFBG sample from Xinjiang Yihua Chemical Industry Co, Ltd. The serious blockage can be observed obviously. As so far, it is not clear for the characteristics and generation mechanism of the blockage. For analysis, the blockage can be classified into two parts, wall-layer blockage (WLB) and center-layer blockage (CLB). To inhibit its formation, it is of significance to analyze the composition, surface morphology, and formation mechanism of the two blockages. In our experiments, WLB and CLB were tested by XRF, XRD, FTIR, SEM-EDS, and SEM-mapping methods. Results showed that WLB presents high content of Fe, Cr, and Ni, and Fe mainly existed in the form of metal oxides. CLB is dominated by Si (43.04%), derived from silica and alkali and alkaline-earth metals silicates, and the migration of Fe, Cr, and Ni elements from the duct material was observed. Compared with WLB, from FTIR analysis, CLB contains more inorganic minerals, and the absorption peak of inorganic minerals is mainly attributed to asymmetric Si-O-Si. Many fine particles are attached to the surface of the WLB, while the surface of the CLB is smooth, and there is noticeable raised texture, which is presumed to be the result of particle melting and agglomerating as the bottom ash enters the duct in the gasification process. For the formation of the blockage, this paper speculates that it is mainly due to the difference in flow resistance near the air nozzle outlet, resulting in the formation of a flow dead zone at the bottom of the gasifier, which leads to large amounts of ash overcoming the outlet resistance and leaking into the air nozzle, and next, the ash corrodes in the tube, resulting in wall deposition and ultimately blocking the air guide duct. Two methods can be tried to avoid or inhibit the formation of blockage in the duct, including optimizing air nozzle with more wear-resistant and heat-resistant materials and adjusting the distance between air nozzles to avoid mutual interference from ash particles.

Investigation on Compositional Structures of the Organic Matter and Biomarker Distributions in Shengli Lignite.

The structural characteristics of the organic matter and biomarker distributions in Shengli lignite (SL) were comprehensively studied by combining a variety of modern analytical techniques and solvent extraction/thermal dissolution. Characterization of SL with Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, solid 13C nuclear magnetic resonance spectroscopy and thermogravimetry showed that organic matter in SL is rich in oxygen functional groups, such as C-O, >C=O, and -COOH, and hydrogen bonds. The hydrogen bonds mainly include -OH···π, self-associated -OH, -OH···ether O, tightly bound cyclic -OH, -OH···N, -COOH dimers, and -SH···N. The highest content of organic nitrogen and sulfur on SL surface are pyrrole nitrogen and aromatic sulfur, respectively. The proportions of aromatic and aliphatic carbons in SL are about 58% and 39%, respectively. The aromatic carbon is mainly composed of protonated aromatic and aromatic bridged carbons; methylene carbon has the highest content among the aliphatic carbons, with chains of average length of 1.43 carbon atoms. The average number of aromatic structural units in the carbon skeleton of SL is about 3, and each aromatic structural unit contains an average of 1-2 substituent groups. Thermogravimetric analysis clarified the distribution of the main types of covalent bonds in SL and their possible cracking temperatures during pyrolysis. The extracts and soluble portion of thermal dissolution from SL were analyzed by a gas chromatograph/mass spectrometer, and a series of biomarkers were identified, mainly concentrated in petroleum ether extract and cyclohexane thermal soluble portion. These included long-chain n-alkanes, isoprenoid alkanes, long-chain n-alkenes, terpenoids, n-alkan-2-ones, long-chain n-alkylbenzene, and long-chain n-alkyltoluene. The comprehensive characterization of the organic matter and the distribution of related biomarkers provided an important scientific basis for understanding the molecular structural characteristics and geochemical information on SL.

Separation and Analysis of Oxygen-Containing Compounds in a Shaanxi Middle/Low-Temperature Coal Tar.

A middle/low-temperature coal tar (M/LTCT) was obtained from a low-temperature carbonization plant in Shaanxi, China. The M/LTCT was separated into light components and coal tar pitch through extraction. A series of alkanes, aromatic hydrocarbons, oxygen-containing arenes (OCAs), and nitrogen-containing arenes were fractionated from light components by medium-pressure preparative chromatography with gradient elution using petroleum ether and ethyl acetate. They were analyzed using a gas chromatography-mass spectrometer (GC-MS) and a Fourier transform infrared spectrometer. The OCAs were analyzed by a Fourier transform Orbitrap MS (quadrupole exactive Orbitrap mass spectrometer), and the molecular distribution of the O 1-O 6 species was studied. OCAs are mainly oxygen-containing aromatic compounds, including aromatic phenols, furans, alkoxy aromatic hydrocarbons, aromatic ethers, aromatic aldehydes, aromatic ketones, and aromatic acids. The position of the oxygen atom on the aromatic ring and the condensation form of the aromatic ring are studied.

Production of Diethyl Maleate via Oxidative Depolymerization of Organosolv Lignin from Wheat Stalk over the Cooperative Acidic Ionic Liquid Pair.

Lignin, the second largest component of biomass, is considered as an important alternative source of fossil reserves for the production of fuels and chemicals. Here, we developed a novel method to oxidatively degrade organosolv lignin into value-added four-carbon esters, particularly diethyl maleate (DEM), with the cooperative catalyst consisting of 1-(3-sulfobutyl) triethylammonium hydrogen sulfate ([BSTEA]HSO4) and 1-butyl-3-methylimidazolium ferric chloride ([BMIM]Fe2Cl7). Under optimized conditions (1.00 MPa initial O2 pressure, 160 °C, 5 h), the lignin aromatic ring was effectively cleaved by oxidation to form DEM with a yield of 15.85% and a selectivity of 44.25% in the presence of the synergistic catalyst of [BMIM]Fe2Cl7-[BSMIM]HSO4 (1/3, mol/mol). The structure and composition analysis of lignin residues and liquid products confirmed that the aromatic units in lignin were effectively and selectively oxidized. Furthermore, the catalytic oxidation of lignin model compounds was explored for obtaining a possible reaction pathway of oxidative cleavage of lignin aromatic units to DEM. This study provides a promising alternative method for the production of traditional petroleum-based chemicals.

Producing Lignin and Ethyl Levulinate from Wheat Stalk Using 1-(3-Sulfobutyl) Triethylammonium Hydrogen Sulfate and USY Zeolite.

The facile, green, and efficient strategy for the separation of lignin from straw and subsequent production of value-added chemicals is crucial to the current utilization of straw. Herein, up to 23.72% of lignin was isolated from wheat stalk over cheap and green 1-(3-sulfobutyl) triethylammonium hydrogen sulfate ([BSTEA]HSO4) in aqueous ethanol (Vethanol: Vwater = 4:1). The acquired lignin was verified as a p-hydroxyphenyl-guaiacyl-syringyl type, which had a narrower molecular weight distribution, better thermal stability, and higher purity compared with those of the lignin obtained using 1-methyl-3-(4-sulfobutyl)-imidazolium hydrogen sulfate and 1-(3-sulfobutyl) pyridinium hydrogen sulfate. Moreover, a carbohydrate-rich liquid containing [BSTEA]HSO4 was obtained by water removal from the waste liquid after lignin separation and further converted to ethyl levulinate (EL) by a one-pot process in the presence of inexpensive and stable USY zeolite. The yield of EL reached 30.23% at 200 °C for 60 min over the presence of 40% [BSTEA]HSO4 and 60% USY zeolite. Under optimal conditions, the yields of lignin and EL can respectively reach 83.89 and 72.28% of those catalyzed by a fresh catalyst after five cycles. In short, the above-mentioned methods present a green, economic, and efficient route for the extraction of lignin and further treatment of the liquid waste generated during the extraction process.

Insight into the Compositional Features of Organic Matter in Xilinguole Lignite through Two Mass Spectrometers.

Ethanolysis of lignite is an effective approach for converting organic matter of lignite to liquid coal derivatives. Xilinguole lignite (XL) was reacted with ethanol at 320 °C. Then ethanol and isometric carbon disulfide/acetone mixture were used to extract the reaction mixture in a modified Soxhlet extractor to afford extractable portion 1 (EP1) and extractable portion 2 (EP2), respectively. According to analysis of EP1 with a gas chromatography/mass spectrometer, phenolic compounds made up more than 33% of the compounds detected. This could be ascribed to the ethanolysis of XL; that is, ethanol could selectively break the Calkyl-O bonds in lignite, producing more phenolic compounds. Furthermore, a quadrupole Orbitrap mass spectrometer equipped with an atmospheric pressure chemical ionization source was used for comprehensive analysis of the compositional features of EP1. The analysis indicated that O1-3, N1O0-2, and N2S1O3-6 were predominant class species in EP1. Nitrogen atoms in NO-containing organic compounds may exist in the form of pyridine or amidogen, while oxygen atoms primarily exist in furan, alkoxy, carbonyl, and ester groups. In addition, possible chemical structures of NO-containing organic compounds were speculated.

Copyrolysis and Cocombustion Performance of Karamay Oily Sludge and Zhundong Subbituminous Coal.

Karamay oily sludge (KOS), Zhundong subbituminous coal (ZSBC), and their equal mass mixture (M KOS/ZSBC) were selected as the research samples, and composition characteristics and pyrolysis performance of KOS, ZSBC, and its mixture were investigated by means of various analytical methods. Results showed that yields of fixed carbon and volatile matter from ZSBC are higher than those from KOS, and the content of moisture in ZSBC is also higher; most of the components in KOS are inorganic minerals, with the ash yield of 71.4%, and the fixed carbon yield of nearly 0. According to Fourier transform infrared spectrometer (FTIR) analysis, the types of functional groups in KOS and ZSBC are basically the same, while the contents of which are different. Thermogravimetry-differential thermogravimetry (TG-DTG) analysis indicated that the mass loss of ZSBC, KOS, and M KOS/ZSBC are 41.1%, 25.7%, and 32.8% with a heating temperature up to 990 °C, respectively. By analyzing the theoretical pyrolysis and combustion TG-DTG profiles of M KOS/ZSBC and the measured composition of the flue gas produced during the tested processes, it is found that the mixture of oily sludge and coal helps generate remarkable combustible gases with significantly reduced CO2, indicating that there is an effective "synergistic effect" between KOS and ZSBC. Based on the Coats-Redfern (CR) model, in the main pyrolysis temperature range, when the reaction order is selected as 1, the kinetic fitting effect of pyrolysis and combustion profiles for ZSBC is better, with the correlation coefficient R 2 > 0.98. While for KOS and M KOS/ZSBC, in N2 atmosphere, the fitting effect is satisfactory as the reaction order is set to 5, in air atmosphere, the better fitting effect is considered that reaction order is selected as 1.

N/O Co-doped Porous Carbons Derived from Coal Tar Pitch for Ultra-high Specific Capacitance Supercapacitors.

In this paper, a series of N/O co-doped porous carbons (PCs) were designed and used to prepare coal tar pitch-based supercapacitors (SCs). The introduction of N/O species under the intervention of urea effectively improves the pseudocapacitance of PCs. The results show that the specific surface area of synthesized N3PC4-700 is 1914 m2 g-1, while the N and O contents are 1.3 and 7.2%, respectively. The unique interconnected pore structure and proper organic N/O co-doping, especially the introduction of pyridine-N and pyrrole-N, are beneficial for improving the electrochemical performance of PCs. In the three-electrode system, the specific capacitance and rate capability of N3PC4-700 are 532.5 F g-1 and 72.5% at the current densities of 0.5 and 20 A g-1, respectively. In addition, the specific capacitance of N3PC4-700 in a coin-type symmetric device is 315.5 F g-1 at 0.5 A g-1. The N3PC4-700 electrode provides an energy density of 43.8 W h kg-1 with a power density of 0.5 kW kg-1 and still maintains a value of 29.7 at 10 kW kg-1. After 10,000 charge/discharge cycles, the retention rate was as high as 96.7%. In order to obtain high-performance carbon-based SCs, the effective identification and regulation of organic N/O species is necessary.

Pyrolysis Kinetic Analysis of Sequential Extract Residues from Hefeng Subbituminous Coal Based on the Coats-Redfern Method.

Sequential extract residues (R i , i = 1, 2, 3, 4, and 5) were obtained from Hefeng acid-washing coal (HFAC) by petroleum ether, carbon disulfide, methanol, acetone, and isometric carbon disulfide/acetone mixture, sequentially. Pyrolysis behavior of the residues was determined using thermogravimetry analysis. The Coats-Redfern method with different reaction orders was used to analyze the pyrolysis kinetic of each sample, and the kinetic parameters, including correlation coefficient (R 2), activation energy (E), and pre-exponential factor (A), were calculated. Results showed that the weight loss of extract residues was higher than HFAC, and pyrolysis behavior varies greatly for residues, which is related to the unstable structure after extraction. From conversion-temperature (α-T) curves, the pyrolysis process was divided into three stages: low-temperature stage (150-350 °C), medium-temperature stage (350-550 °C), and high-temperature stage (550-950 °C). The medium-temperature stage made great contribution to the process of pyrolysis, which was dominated by depolymerization and decomposition reaction. The relationship between kinetic parameters and reaction order showed that the swelling effect is an important reason for the discrepancy of E for each sample in the process of pyrolysis.

Pexophagy is critical for fungal development, stress response, and virulence in Alternaria alternata.

Alternaria alternata can resist high levels of reactive oxygen species (ROS). The protective roles of autophagy or autophagy-mediated degradation of peroxisomes (termed pexophagy) against oxidative stress remain unclear. The present study, using transmission electron microscopy and fluorescence microscopy coupled with a GFP-AaAtg8 proteolysis assay and an mCherry tagging assay with peroxisomal targeting tripeptides, demonstrated that hydrogen peroxide (H2 O2 ) and nitrogen depletion induced autophagy and pexophagy. Experimental evidence showed that H2 O2 triggered autophagy and the translocation of peroxisomes into the vacuoles. Mutational inactivation of the AaAtg8 gene in A. alternata led to autophagy impairment, resulting in the accumulation of peroxisomes, increased ROS sensitivity, and decreased virulence. Compared to the wild type, ΔAaAtg8 failed to detoxify ROS effectively, leading to ROS accumulation. Deleting AaAtg8 down-regulated the expression of genes encoding an NADPH oxidase and a Yap1 transcription factor, both involved in ROS resistance. Deleting AaAtg8 affected the development of conidia and appressorium-like structures. Deleting AaAtg8 also compromised the integrity of the cell wall. Reintroduction of a functional copy of AaAtg8 in the mutant completely restored all defective phenotypes. Although ΔAaAtg8 produced wild-type toxin levels in axenic culture, the mutant induced a lower level of H2 O2 and smaller necrotic lesions on citrus leaves. In addition to H2 O2 , nitrogen starvation triggered peroxisome turnover. We concluded that ΔAaAtg8 failed to degrade peroxisomes effectively, leading to the accumulation of peroxisomes and the reduction of the stress response. Autophagy-mediated peroxisome turnover could increase cell adaptability and survival under oxidative stress and starvation conditions.

A zinc finger suppressor involved in stress resistance, cell wall integrity, conidiogenesis, and autophagy in the necrotrophic fungal pathogen Alternaria alternata.

The tangerine pathotype of Alternaria alternata can withstand high-level reactive oxygen species (ROS). By analyzing loss- and gain-of-function mutants, this study demonstrated that a Cys2His2 zinc finger-containing transcription regulator, A. alternata Stress Response Regulator 1 (AaSRR1), plays a negative role in resistance to peroxides and singlet-oxygen-generating compounds. AaSRR1 plays no role in cellular susceptibility or resistance to superoxide-producing compounds. AaSRR1 also negatively regulates conidiogenesis, maintenance of cell wall and membrane integrities, and chitin biosynthesis. Some wild-type hyphae displayed necrosis after exposure to 30 mM H2O2, whereas AaSRR1 deficient mutant (ΔAaSRR1) hyphae had visible granules and vacuoles. sGFP-AaATG8 proteolysis assays revealed that H2O2 and starvation could trigger autophagy formation in both wild type and ΔAaSRR1. Autophagy occurred at higher rates in ΔAaSRR1 than wild type under both conditions, particularly after H2O2 treatments, indicating that autophagy might contribute to ROS resistance. Upon exposure to H2O2 or under starvation, AaSRR1 was translocated into the nucleus, even though the expression of AaSRR1 was decreased. AaSRR1 is required for vegetative growth but is dispensable for fungal virulence as assayed on detached calamondin leaves. AaSRR1 suppressed the expression of the gene encoding a HOG1 mitogen-activated protein (MAP) kinase implicated in ROS resistance. Mutation of AaSRR1 increased catalase activity but decreased superoxide dismutase activity, leading to fewer ROS accumulation in the cytosol. Nevertheless, our results indicated that AaSRR1 is a transcription suppressor for ROS resistance. This study also revealed tradeoffs between stress responses and hyphal growth in A. alternata.

Analysis of Pyrolysis Performance and Molecular Structure of Five Kinds of Low-Rank Coals in Xinjiang Based on the TG-DTG Method.

Taking five coal samples (FCSs) in Xinjiang as the research object, characterizations such as proximate analysis, ultimate analysis, Fourier transform infrared (FTIR), and thermogravimetry-differential thermal analysis (TG-DTG) were carried out. The Coats-Redfern model was used to simulate pyrolysis kinetics of FCSs under different reaction orders (ROs). The results showed that except for HSBC, the R 2 of the other four coal samples are all higher than 0.9, which showed a good correlation effect. FCSs present similar reaction activation energy in the same RO and temperature range. Results of FTIR showed that the hydroxyl groups of FCSs, in the range of 3100-3600 cm-1, were mainly self-associated hydroxyl hydrogen bonds and hydroxyl π bonds, and they occupied over 63%. Among them, the pyrolysis characteristic index (D) of XBC was 4.139 × 10-6, higher than those of other samples, and it showed good pyrolysis performance. Moreover, by reducing the temperature range appropriately, the fitting results showed a better correlation effect.

Functional Group Characteristics and Pyrolysis/Combustion Performance of Karamay OS Based on FT-IR and TG-DTG Analyses.

Proximate analysis, ultimate analysis, Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetry-differential thermal analysis characterization were carried out on oily sludge (OS) samples OS1-OS5, from Karamay, Xinjiang, China. The Coast-Redfern model (CRm) was used to simulate the pyrolysis and combustion kinetics of oily samples. The results showed that the peak area percentage of benzene ring trisubstitution of OS5, in the range of 700-900 cm-1, is close to 75%, corresponding to its high volatile content. Based on the kinetic analysis by the CRm, it is found that the fitting degree of the five samples is better when the reaction order is selected as n = 2, with R 2 close to 1.00 and 2RT/E to 0. Among them, the S N and D W of OS5 are 17.8 × 10-10%2 min-2 °C-3 and 0.10899 × 10-5% min-1 °C-2, respectively, higher than those of other samples, indicating a good combustion performance.

Effect of Swelling by Organic Solvent on Structure, Pyrolysis, and Methanol Extraction Performance of Hefeng Bituminous Coal.

N-methyl-2-pyrrolidone (NMP), pyridine (Py), tetrahydrofuran (THF), and tetralin (THN) were used to swell Hefeng acid-washed bituminous coal (HBCAC). The swelling effect on HBCAC by each solvent is different, among which NMP presented well swelling performance, with a swelling degree of 2.11. FTIR results showed that acid washing and swelling processes presented a marginal effect on HBC, and there was no damage to the macromolecule structure of the coal. TG-DTG profiles of the swollen coals illustrated that the total weight loss of each sample was lower than that of the acid-washing one, while the temperature of the maximum weight loss rate peak was almost unchanged, around 445 °C. Extract yield by methanol followed the order of HBCAC > HBC > HBCAC-NMP (swelled by NMP), showing that acid washing promoted the methanol extraction process, with a higher extract yield of 3.21%, which is twice that of HBC (1.66%).

Detoxification modification of coal-tar pitch by ultraviolet & microwave radiation-enhanced chemical reaction and toxicity evaluation by chemical index and cytotoxicity assay in vitro.

Although coal tar pitch (CTP) has a large yield in China, its large-scale and effective utilization is significantly hindered because of existing and possibly releasing polycyclic aromatic hydrocarbons (PAHs). Therefore, it is an imminent problem how to prepare an environmentally friendly CTP by detoxification modification. In the investigation, a typical CTP was subjected to structural characterization via solid-state 13C NMR and gas chromatograph/mass spectrometer, which confirmed the existence of dominant PAHs such as fluoranthene, pyrene, as well as benzo[a]pyrene, and few heterocyclic compounds. Subsequently, the CTP was modified using 10-undecenal via alkylation reaction enhanced by ultraviolet & microwave radiation. Compared with the original CTP, the total content of 16 toxic PAHs in the modified CTP decreased with a reduction efficiency of above 90%. According to different environmental standards, toxic equivalent quotient of CTP after modification was reduced by above 90%. In order to veritably and fully evaluate the toxicity of CTP, a living vascular smooth muscle cell (A-10 cell) in vitro was used in the cell counting kit-8 assay. The viability of A-10 cell was always higher when exposed to modified CTP than the original CTP. These results powerfully indicated that the enhanced modification was actually effective and efficient for reducing the toxicity of CTP.

Steroidal Glycosides from Allium tuberosum Seeds and Their Roles in Promoting Testosterone Production of Rat Leydig Cells.

A systematic phytochemical study on the components in the seeds of Allium tuberosum was performed, leading to the isolation of 27 steroidal glycosides (SGs 1-27). The structures of SGs were identified mainly by nuclear magnetic resonance and mass spectrometries as well as the necessary chemical evidence. In the SGs, 1-10 and 22-26 are new steroidal saponin analogues. An in vitro bioassay indicates that 1, 2, 7, 8, 10, 13-15, 20, 23, and 26 display promotional roles in testosterone production of rat Leydig cells with the EC50 values of 1.0 to 4.5 µM, respectively.

Sequential thermal dissolution of two low-rank coals and characterization of their structures by high-performance liquid chromatography/time-of-flight mass spectrometry and gas chromatography/mass spectrometry.

RATIONALE: Gas chromatography/mass spectrometry (GC/MS) and high-performance liquid chromatography/time-of-flight mass spectrometry (HPLC/TOF-MS) were used to separate and reveal the molecular characteristics of organic matter in low-rank coals. METHODS: Six soluble portions (SPs) were obtained by sequential thermal dissolution (TD) of two low-rank coals in the order of cyclohexane, acetone and methanol solvents at 300°C. Organic matter with different molecular characteristics were enriched in eachTD extract, which was further separated and analyzed by GC/MS and HPLC/TOF-MS using an electrospray ionization source in positive mode to obtain a comprehensive understanding of the structural composition of coals. RESULTS: Low polarity compounds like alkanes and arenes have a better solubility in cyclohexane. Phorone has the highest relative abundance in the acetone SPs, and the main compounds detected in the methanol SPs are alcohols and phenols. According to the data from HPLC/TOF-MS, most of the oxygen atoms are in the form of carbonyl and alkoxy groups. The nitrogen-containing compounds in SPs are mainly saturated aliphatic amines and pyridines. The sulfur-containing compounds mainly exist in the form of thioalkanes and thiophenes. CONCLUSIONS: Non-destructive methods were used to obtain soluble matter from coals, and different chromatographic and mass spectrometric techniques were used to separate and analyze the organic matter in coals. Detailed molecular structural information was obtained for the efficient and clean utilization of low-rank coals.

Preparation of layered-porous carbon from coal tar pitch narrow fractions by single-solvent extraction for superior cycling stability electric double layer capacitor application.

Coal tar pitch (CTP) with high carbon content and wide source of raw materials was an excellent precursor for the preparation of porous carbons (PCs). CTP was composed of polycyclic aromatic hydrocarbons (PAHs) with complex molecular size and chemical structure, the separation of CTP into several fractions with relatively narrow molecular weight by solvent extraction was of significance for CTP utilization. In this paper, CTP was treated by single-solvent extraction (carbon disulfide, acetone and ethyl acetate), and the six fractions were used as raw materials to prepare PCs as electrode material for electric double layer capacitor. The fractions were well characterized and the effect of mass distribution of different narrow fractions on structure property and electrochemical performance of the PCs was studied. The PCs prepared by carbon disulfide extract, acetone raffinate and ethyl acetate extract, containing more PAHs, exhibited the excellent specific capacitance performance in comparison with its residual components. The remarkable performance might contribute in the enhanced transport of electrolyte ions via the molecular graphene structure of PAHs. Additionally, the PC prepared by carbon disulfide raffinate showed outstanding cycling performance (99.7% at 2 A g-1 after 15,000 cycles) which was related to its unique layered porous structure.

N/O co-doped porous interconnected carbon nanosheets from the co-hydrothermal treatment of soybean stalk and nickel nitrate for high-performance supercapacitors.

Porous interconnected carbon nanosheets (PICNs) with high electrochemical performance were prepared by doping urea and a co-hydrothermal precursor derived from soybean stalk (SS) and nickel nitrate. The specific surface area and average pore diameter of the as-synthesized PICNs are 2226.29 m2 g-1 and 1.89 nm, and their N and O contents are 5.08% and 9.4%, respectively, which is beneficial for increasing pseudocapacitance. Furthermore, the doping of the metal Ni increases the graphitization degree of the PICNs and promotes the conversion of pyridine-N to graphitized-N. Therefore, the PICNs possess a high specific capacitance of 407 F g-1 at a current density of 0.5 A g-1, a high capacitance retention of 78.62% even at 20 A g-1, and an outstanding cycling stability (over 93% retention rate after 10,000 charge/discharge cycles). Moreover, an energy density of 36.11 W h kg-1 is achieved at a power density of 517.8 W kg-1 during a two-electrode system test, and a retention rate of 87.5% is obtained after 10,000 cycles. This co-hydrothermal treatment as well as nitrogen-doping approach for preparing porous interconnected carbon from SS not only represents an alternative strategy for carbon-based supercapacitor materials but also provides a new option for the utilization of waste SS.