Search

Mineral matter, including minerals and non-mineral elements, in coal is of great significance for geological evolution, high-value coal utilization, and environment protection. The minerals and elemental geochemistry of Late Permian coals from the M8 coal seam, Shihao mine, Songzao coalfield in Chongqing, were analyzed to evaluate the sediment source, sedimentary environment, hydrothermal fluids, and utilization prospects of critical metals. The average total sulfur (4.21%) was high in coals, which mainly exists in the forms of pyritic sulfur. Kaolinite, pyrite, calcite, quartz, illite and illite/smectite (I/S) mixed layers, and anatase predominated in coals, with trace amounts of chlorite, ankerite, and siderite. Epigenetic cell- and fracture-filling pyrite, veined calcite, and ankerite were related to hydrothermal fluids and/or pore water after the diagenesis stage. Compared to the world's hard coals, As and Cd are enriched in the Shihao M8 coals, and Li, Cr, Co, Zr, Mo, Pb, and Tb are slightly enriched. These high contents of sulfophile elements may be related to seawater intrusion. The terrigenous clastics of the Shihao M8 coals originated from the felsic–intermediate rocks atop the Emeishan Large Igneous Provinces (ELIP) (Kangdian Upland), while the roof and floor samples were derived from Emeishan high-Ti basalt. Through the combination of sulfur contents and indicator parameters of Fe2O3 + CaO + MgO/SiO2 + Al2O3, Sr/Ba and Y/Ho, the depositional environment of peat swamp was found to be influenced by seawater. Although the critical elements in coal or coal ash did not reach the cut-off grade for beneficial recovery, the concentration of Li and Zr were high enough in coal ash. [ABSTRACT FROM AUTHOR]

This study highlights the response of the periodic variation of the geochemical behavior of elements to the thermal metamorphism of coal by considering the differentiation mode and differentiation degree of elements of the C2 coal seam in the Fengfeng mining area of the Handan Coalfield in Hebei, China. The periodic variation of the geochemical behavior of elements was observed to change towards a certain direction as the degree of metamorphism of a geological body increased. Based on the coincidence degree (or similarity degree) between the geochemical behavior of elements and periodic variation of elements, the 57 elements in this study were divided into two levels. The periodic variation of the geochemical behavior of first‐level elements was largely synchronous with that of their first ionization energy, suggesting that only one differentiation mode exists and the elements are mainly inorganically associated. The differentiation mode of the second‐level elements deviated to a certain extent from their first ionization energy; the larger the deviation, the more complicated and diverse was the differentiation mode. Among the second‐level elements, the grade of coal metamorphism has evident and intuitive effects on the proportion of elements with particular structural features, such as the 4q+3 type of elements and the odd‐odd elements. In addition, the distribution of elements in organic and inorganic matter within coal are subject to the structural features of the elements. The differentiation mode and differentiation intensity of elements could be characterized by the hierarchical parameter and differentiation intensity. The hierarchical parameter and differentiation intensity of certain elements showed a good positive or negative correlation with Rmax in coal. The 57 elements in this study were quantitatively ordered according to the degree of magmatic hydrothermal fluid influence and thermal metamorphism of coal through graphs depicting the goodness of fit, correlation coefficient with Rmax, and differentiation intensity. The results of this study are consistent with the results of previous field research, illustrating the scientific significance and application value of this study on the periodic variation of the geochemical behavior of elements. [ABSTRACT FROM AUTHOR]

The "geochemical effect of lanthanides" is a new concept proposed by the authors during the past decade. This concept reflects lanthanide shrinkage in elemental geochemistry, and it is statistically quantifiable. However, the geological significance of the various parameters of the equations obtained following quantization is not entirely clear. Cooperation and discussions from scholars in related research fields of rare earth elements in geology are required. In the present paper, from the perspective of coal geochemistry, the metamorphic coal seam of C2 series in Fengfeng Mine of Handan Coalfield in Hebei Province, China was used as an example. The geochemical significance of parameters in geochemical effect regression equation for lanthanides was evaluated, and two new formulas (regression equations) that characterized the geochemical behaviors of lanthanides were proposed. On this basis, concepts related to the geochemical effect of lanthanides, such as "individual parameters", "parameters in common", "two-sided parameters", and the "deviation value" of lanthanides, were proposed. In this study, it was proved that the goodness of fit for all types of function regression equations for lanthanides and the radii of their trivalent ions, and the "deviation value" of lanthanides, were all "individual parameters" that could indicate the post-modified geological environment of C2 coal seam, such as the influence from magmatic-hydrothermal fluids. A covariant figure was constructed according to these individual parameters and other indexes, and the C2 coal seam in Handan was effectively divided into two different metamorphic series of A (C2 coal seam uninfluenced or slightly influenced by magmatic-hydrothermal fluids) and B (C2 coal seam strongly influenced and evidently changed by magmatic-hydrothermal fluids). Consequently, the scientific significance of all the parameters for lanthanides in an identifying series of metamorphic coals within the geochemical effect regression equation was further clarified. [ABSTRACT FROM AUTHOR]

The recovery of lithium (Li) from coal ash has gained growing attention as a promising Li resource. Compared with extensive studies on the modes of occurrence of Li in coal and coal ash, few studies have investigated the migration and mineral host changes of Li during coal combustion. This study investigates the modes of occurrence of Li in feed coal, the conversion of minerals, the Li-host changes, and the influencing factors during coal combustion. The results show that Li is enriched in the feed coal, possibly mainly in the octahedral sites of kaolinite and illite/smectite (I/S). Kaolinite and I/S are dehydrated and dehydroxylated at high temperatures to form aluminosilicate glass, which then partially transforms into pseudomullite at 826 °C and further converts to mullite at 1282 °C. Temperature is the main factor controlling the Li-host changes during coal combustion. The proportion of easily leachable Li decreases with increasing in temperature (400–1000 °C), and the leachability of Li is optimal at 500 °C regarding possible extraction prospects. Oxy-fuel combustion reduces the temperature of coal particles, resulting in a relatively higher proportion of easily leachable Li from oxy-fuel combustion compared with air combustion at 700 °C. The Li-host phase changes are discussed in detail using sequential chemical extraction assisted with thermodynamic calculation (HSC Chemistry 10). The Li related to kaolinite and I/S in coal mainly migrates into the octahedral positions of clay minerals to form lithium aluminosilicate. Portions of the Li react with Fe, Mn, and S to form lithium manganese/iron oxides and lithium sulfate. This study evaluates the extraction potential of Li from coal by experimental heating under different atmospheres and the study of mineralogical changes of Li-hosts, providing practical guidance for the recovery of Li from coal. • Li is enriched in the feed coal, which is related to kaolinite and illite/smectite (I/S). • Temperature is the main factor controlling the occurrence transformation of Li. • The most effective extraction of Li occurs when the coal is heated to 500 °C in air. • The easily leachable Li in oxy-fuel combustion is higher than in air combustion. • The Li-hosts were determined by thermodynamic energy minimization. [ABSTRACT FROM AUTHOR]

• The Tröger base analogue coordinated with potassium iodide and containing crown ether CATB-KI was fabricated. • The acidified CATB-KIs shown high catalytic efficiency to cyclic carbonates. • The synergistic mechanism has been proved in terms of experimental results and calculation of dynamics. Tröger's bases (TB) containing two steric nitrogen atoms, are alternated as building block for constructing molecular acceptors to form covalent bonds with acids, making TB a promising catalyst. Herein, TB analogs fabricated with crown ethers were knitted by condensation reaction and combined with potassium iodide as a brand-new catalytic system (CATB-KIs), which were characterized using FT-IR, 13C CP MAS NMR, SEM, TGA, and XPS spectroscopy respectively. The generated CATB-KIs exhibited excellent performance for CO 2 fixation reaction with epoxides to produce cyclic carbonates under mild conditions, and the catalytic activity could be further improved by coordinating with acids beforehand, in which HBr performs fascinated activity. After 12 h, the corresponding cyclic carbonate from epichlorohydrin with 95.1% yield was detected at mild conditions with solvent-free in the presence of CATB-KI-2 and HBr. A series of terminal epoxides were converted into desired cyclic carbonates with desirable yields. The catalyst could be recovered successfully and reused six times without significant loss of activity. Finally, dynamics study on catalytic mechanism has been accomplished and the activated energy was calculated as 72.1 kJ/mol. A synergistic catalytic mechanism of hydrogen bonding and I anion has been proposed to account for the excellent catalytic activity of this catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

The modes of occurrence of trace elements (TEs) in coals are important for assessing the potential for economic extraction of valuable TEs (Ge, Ga, Li, REY, PGEs, etc.) and to determine the environmental risk of hazardous TEs (F, Cl, As, Cr, Cd, Pb, etc.). To date, associations of TEs with inorganic components (minerals) are well understood. However, information on the relationships of TEs with organic matter in coals is relatively limited. This review compares indirect and direct methods employed to investigate the modes of occurrence of TEs in coals, focusing on the associations of TEs with organic matter. Those TEs with a strong organic relationship are identified and detailed; they include Ge, U, Ga, REY, Be, B, As, Se, Cl, Br, and W. Other TEs weakly related with organic matter in coals are also detailed in the order of their periodic table groups. Finally, the influence of coal rank on the relationship of TEs with organic matter is discussed, and an inherent geochemical law, i.e., the element periodic law, is proposed to govern the relationship. [ABSTRACT FROM AUTHOR]

The indicative significance of organic matter in fossil fuels, particularly polycyclic aromatic compounds (PACs), is a current research hotspot. Petrology, minerals, and organic matter in Late Permian coals from the Moxinpo (MXP) mine located in Chongqing, southwestern China, were analyzed to evaluate the coal rank, coal-forming material source and thermal maturity of organic matter, and sedimentary environment of the peat swamp. Vitrinite and inertinite were dominated by collotelinite, collodetrinite, inertodetrinite, fusinite, and semifusinite. Owing to the high maturity of the coals, liptinite was not observed under the microscope. Clay (kaolinite) and pyrite were the primary minerals in the MXP coals, followed by calcite, quartz, trace amounts of anatase, gypsum, xenotime, and bastnaesite. The minerals in the MXP coals were authigenic primarily in the epigenetic stage. The extract yield of organic matter in coals was low (0.30%), and the saturated and aromatic fractions accounted for approximately 60% of the extractable organic matter. Low ratios of saturated to aromatic compounds reflected the terrestrial higher plants input and high maturity level of the coals. The extracted yield in the host rock samples was much lower than in the coals, while the proportion of saturated hydrocarbons was relatively high. The marine-continental transitional sedimentary environment, distribution of n -alkanes, ∑ C 21 − /∑ C 22 + , and pristane (Pr)/ n -C 17 vs. phytane (Ph)/ n -C 18 indicated that the organic matter originated from the input of terrestrial higher plants and was accompanied by the contribution of marine lower phytoplankton and aquatic organisms. The coal-forming environment of the coal seam was reductive according to the Pr/Ph and sulfur-containing compounds of dibenzothiophenes and benzonaphthothiophenes. The thermodynamic stability controls the presence of polycyclic aromatic hydrocarbons in extractable organic matter. Isomeric compounds with high stability had higher concentrations, such as 2-methylnaphthalene, 2,6 + 2,7-DMN, 4- methylbiphenyl, and 2- methylphenanthrene. [Display omitted] • Macerals were primarily vitrinite and inertinite, while liptinite was absent. • Minerals were dominated by kaolinite, pyrite, calcite, and quartz in the MXP coal. • Organic matter in coals was dominated by the input of terrestrial higher plants. • Coal-forming environment was a reductive and marine-continental transitional environment. • Concentration of isomer compounds was controlled by thermodynamic stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sulfur forms may significantly influence the SPACs formation. • High organic-sulfur coal contains more SPACs. • Sulfur forms were controlled by peat forming environments. • SPACs, sulfur forms and peat forming environments belong to a geological system. Sulfur-containing polycyclic aromatic compounds (SPACs) are important compounds found in coal. Previous research suggests that sulfur content is the most important controlling factor for SPAC formation. However, different forms of sulfur occur in coal. To study the influences of different sulfur forms on SPAC-formation mechanisms, six samples collected from the No. 1 4 coal seam of the Yuzhou Coalfield were identified to be high-pyrite sulfur coal (HPSC). Ten samples collected from the No. 1 1 coal seam from the Yuzhou Coalfield were identified to be high organic-sulfur coal (HOSC). Four samples collected from the No. 1 5 coal seam of the Dengfeng Coalfield were identified to be high sulfate-sulfur coal (HSSC). The study of the influences of different sulfur forms on SPAC-formation may better understand SPAC-formation mechanism. The collected samples were investigated using a microscope and organic geochemical methods. The microscopic findings revealed that the three coals have similar random vitrinite reflectance (R r) values and have undergone similar geothermal processes. The geochemical results showed that the SPAC species and their contents in the HPSC, HSSC, and HOSC samples are very different. The HOSC samples of the No. 1 1 coal seam contained 65 SPACs; however, the HPSC samples of the No. 1 4 coal seam contained only 25 SPACs, and the HSSC samples of the No. 1 5 coal seam contained 44 SPACs. The average ratio of total-SPAC/total-PAC (T -SPAC/ T -PAC) reaches 55.0 wt% in the HOSC samples, whereas the ratio is only 19.3 wt% in the HPSC samples, and 22.6 wt% in the HSSC samples. Coal maturity should not be a factor in the SPAC discrepancy because the three coal seams herein underwent similar geothermal processes. The sulfur forms may explain the apparent discrepancy of SPACs. Compared to the other two types of coal, the contents of pyrite, sulfur, and iron (Fe) are much higher in HPSC, and sulfur prefers to react with Fe to form pyrite, resulting in a lower SPAC content in HPSC and HSSC. The sulfur forms were influenced by the peat/coal-forming environments, which were affected by storm events. Finally, possible comprehensive formation pathways for major SPAC species have been proposed. [ABSTRACT FROM AUTHOR]

Gallium (Ga), which is a rare valuable metal, has been found to be anomalously enriched in coal to the extent that it may be considered as an economic resource. Recovery of Ga from coal or coal combustion byproducts offers a promising alternative way to obtain this metal, and such techniques could probably lead to economic gains and positive impacts on the environment. Thus, geochemical research and technical investigations of Ga-bearing coal would be helpful in assessing the potential for economic extraction of the Ga. The present review of Ga in coal focuses on analytical methods that can be used to determine Ga concentrations, patterns of Ga enrichment in coal and formation of economic Ga-enriched coal deposits, modes of occurrence of Ga and its origins, the behavior of Ga during coal combustion and gasification, and currently available recovery techniques for Ga. Moreover, insufficiencies in previous research are identified and future research needs regarding Ga in coal are evaluated and discussed. [ABSTRACT FROM AUTHOR]

Critical metals play an irreplaceable role in supporting the development of the global economy and emerging industries. Their short supply makes the recovery of critical metals from alternative sources, such as coal ash, a research hotspot. In this study, Chongqing Power Plant coal and its combustion products, which are rich in a variety of critical metal elements, were selected for the study. The enrichment, distribution, and occurrence mode of critical elements in the products of coal combustion was studied, and improved sequential chemical extraction procedure, and their extraction potential was proposed and discussed. The results show that the contents of the most critical elements in different coal ashes are generally high in the order of fly ash, slag, and bottom ash. The critical elements Li, Ga, Sr, Zr, Hf, Nb, Ta, and rare earth elements and yttrium (REY) are enriched in fly ash and the contents of Ga, Nb, and REY exceed their respective industrial utilization grades, which have great recovery potential. Lithium, Ga, Nb, Ta, and REY are mainly distributed in small particle sizes in non-magnetic fly ash and occur in aluminosilicate glass, followed by mullite and quartz. Three categories of extractability are proposed: easy-to-extract form, relatively easy-to-extract, and difficult-to-extract forms. Finally, future research should focus on the collaborative extraction of multiple critical elements (such as Li, Ga, Nb, and REY) from coal ash. [Display omitted] • Most critical elements in different coal ashes are high. • Critical elements Li, Ga, Sr, Zr, Hf, Nb, Ta, and REY are enriched in fly ash. • An improved sequential chemical extraction procedure was developed. • Li, Ga, Nb, Ta, and REY concentrate in small particle-sized, non-magnetic fly ash. • Three categories of extractability of critical elements are proposed. [ABSTRACT FROM AUTHOR]

Abstract: Eighteen semianthracite samples of the No. 9 coal seam in the Gequan Mine, Xingtai Coalfield, China were investigated, primarily by microscope and organic geochemical methods. The petrological results showed that the vitrinite random reflectance (R o) is 2.36% and the maceral group was dominated by vitrinite. The gas chromatograms (GC) of the saturates display a monomodal or bimodal outline of n-alkane peaks, generally from n-C10 to n-C31, resulting in two ranges of ∑(C1–C21)/∑(C22–C34) values. Most of the coal samples exhibit consistently similar parameters, such as pristane/n-C17 and phytane/n-C18 ratios, whereas samples with different Pr/Ph values may have been the result of varied redox depositional conditions. The distributions of the polycyclic aromatic compounds (PACs) identified in the aromatics were generally similar due to the similar high rank of the coal samples. Under the high thermal maturity, the PACs with greater thermodynamic stabilities (including 2-methylnaphthalene, 2,6- and 2,7-dimethylnaphthalenes, 2- and 3-methylphenanthrenes, and 2,6- and 2,7-dimethylphenanthrenes) were present at higher concentrations than those of less thermodynamically stable PACs. A portion of these PACs most likely originated from a secondary generation. The generally higher contents of dibenzothiophenes and benzonaphthothiophenes were most likely generated under the control of hydrothermal fluids. However, the coal-forming environment may also have played a role for higher contents of dibenzothiophenes and benzonaphthothiophenes. [Copyright &y& Elsevier]

Abstract: An artificial maturation experiment at 80°C was conducted for >5years to investigate the early diagenetic transformations of organic matter (OM), mainly terpenoids, in conifers. The diagenetic products of aromatic hydrocarbons were determined in the earlier and later stages of maturation, namely, after >1year and after ∼5.5years. The OM in contemporary coniferous plants (Cedrus deodara and Platycladus orientalis) was also characterized for comparison. The results reveal that during the early diagenesis of OM from conifers, biological terpenoids were transformed into diagenetic aromatic terpenoids and common polycyclic aromatic hydrocarbons. Some polar terpenoids, such as dehydroabietate aldehydes and abietatetraenoic acid, were detected and identified. Information on these biological and evolutionary terpenoids may improve the understanding of their diagenetic pathways. The experimental data also show that the diagenesis of dehydrogenated and aromatic terpenoids and polycyclic aromatic hydrocarbons is affected by different experimental inorganic conditions. High salinity is favourable to diagenesis in aromatic fractions. Meanwhile, heavy metals such as lead and iron may delay and interrupt the transformation of terpenoids, respectively. [Copyright &y& Elsevier]

Lightweight ceramic proppants are prepared using coal gangue, fly ash, and bauxite as raw materials, and a mixture of manganese dioxide and magnesium oxide is used as composite additives. The total content of the coal gangue and fly ash in the raw materials reaches up to 70 wt%. The effects of coal gangue and fly ash precalcination, sintering temperature, and composite additive content on the phase compositions, microstructures, and performances of the resulting ceramic proppants are studied in detail. The ceramic proppant prepared at 1285 °C using 1 wt% of the composite additive is composed of quartz, corundum, and mullite. It also presents the desired sphericity, roundness, and microstructure. The apparent density, bulk density, and breakage ratio of the ceramic proppant described above are 2.55 ± 0.06 g/cm3, 1.03 ± 0.02 g/cm3, and 8.30 ± 0.68% at 35 MPa, respectively. This ceramic proppant belongs to lightweight ceramic proppants and meets the requirement of the 5K grade in the standards of SY/T 5108-2014 and API STD 19C-2018. [ABSTRACT FROM AUTHOR]

Driven by the high energy demand and environmental concerns, biodiesel as a substitute for fossil fuels is recognized as promising renewable and clean energy. Biodiesel has gained interest around the world over the last few years because it could be used to reduce most regulated exhaust emissions. Herein, we discuss the application of catalytic transesterification by using ionic liquids (ILs) catalyst with alcohol and waste oil for the clean synthesis of biodiesel in order to reduce the emission of NO x and CO. However, the running cost of this process is still higher than that of the conventional chemical transesterification. Non-edible sources such as waste oil, non-edible vegetable oil, and waste animal oil are commonly used to produce biodiesel due to their low cost and no dependency on the food chain. This review provides an overview of the recent progresses in improving the biodiesel production process by using ILs and determining the activation energy and the properties of the finished product. In addition, the future direction in biodiesel production via ILs catalysis in the transesterification has been discussed. • We review the catalytic activity of the various catalysts. • A biodiesel yield was achieved by using the ionic liquids with diethyl carbonate. • The ionic liquid with diethyl carbonate was shown to be the most efficient procedure. • The process can generate high purity green fuel that meets the quality demands. [ABSTRACT FROM AUTHOR]

Fixing the greenhouse gas CO2 through epoxide helps to mitigate worldwide ecological troubles. The applications of metal‐free and solvent‐free catalysts remain a challenge for CO2 catalytic conversion. In this work, an array of quaternary ammonium salts derived from polyethyleneimine with hydroxyl groups ([PEI‐GDMAB‐Cn]Br) were constructed by the reaction of branched PEI with a molecular weight of 10000 and glycidyl alkyl dimethylammonium bromide. A range of experiments were designed to demonstrate that [PEI‐GDMAB‐Cn]Br can be considered as a valid metal‐free and solvent‐free homogeneous catalyst for the CO2‐epoxide cycloaddition reaction. Among of [PEI‐GDMAB‐Cn]Br, [PEI‐GDMAB‐C18]Br catalyzed the model reaction of CO2 and epichlorohydrin under optimized reaction conditions (T=80 °C, 1.0 atm CO2, catalyst 1 mol%, ECH 15 mmol, 16 h) and the conversion achieved at 97.5 %. Moreover, the catalyst exhibited stable reusability and broad substrate applicability, which was used in the following cycle succinctly, because of self‐separated properties by temperature control. The [PEI‐GDMAB‐C18]Br catalyzed reaction process was detected as a pseudo‐first‐order reaction after kinetic studies and an Ea was calculated to be 50.65 kJ/mol. A combinatorial catalytic mechanism of hydrogen bonding and bromide ions is suggested to explain the remarkable catalytic performance of this bifunctional catalyst. [ABSTRACT FROM AUTHOR]

A series of carbon sphere supported with adjustable alkyl length substitutes polymeric ionic liquids bearing hydroxylamino-anchored functional groups by covalent connection were fabricated from copolymerization of carbon sphere with vinyl based monomeric ionic liquids, which were constructed from 1-glycidyl-3-vinylimidazolium bromide and alkyl amines. The carbon sphere hybrid polymeric ionic liquids were characterized by FT-IR, SEM–EDS, N2 adsorption/desorption isotherm, elemental analysis, 13C MAS NMR and XPS, which were candidated as heterogeneous catalysts for CO2-epoxide cycloaddition reactions to product cyclic carbonates at mild conditions without co-catalyst and metal ion. The introduced functional groups on carbon sphere could accelerate the reaction process and yields of above 90% were obtained for various cyclic carbonates under optimized conditions. Finally, kinetic experiments were also carried out to reveal reaction mechanism and the activated energy was determined as 114.9 kJ/mol. Therefore, this study provides a new approach to fabricate multifunctional heterogeneous materials for coupling reaction of CO2 under mild conditions. [ABSTRACT FROM AUTHOR]

Optimization and kinetic modeling of methyl ester production from non-edible tung nut oil (Vernicia fordii) and methanol using a solid acidic ionic liquid polymer as a catalyst were performed in this study. A solid acidic ionic liquid polymer was synthesized using vinyl imidazole, 1, 3-propane sulfonate, N, N- dimethyl dodecylamine, allyl bromide and toluene, characterized and used for transesterification of tung nut oil for methyl esters synthesis. The optimum reaction conditions resulted in highest methyl ester yield of 91% were a tung-nut- oil -to-methanol molar ratio of 1:1.5, solid acidic ionic liquid polymer catalyst loading of 160 wt % based on the oil, reaction time of 6 h, agitation speed of 400 rpm and reaction temperature of 65 °C. Further kinetic studies performed at different temperatures revealed that the conversion of tung nut oil to methyl ester follows the first order reaction. Methyl esters were purified using an ion exchange resin and then analyzed by GC-MS. The activation energy (Ea) was calculated as 72.81 kJ mol−1. The properties of methyl esters such as kinematic viscosity at 40 °C, density at 25 °C, cloud point and pour point were also determined. Methyl esters met the quality standard defined under ASTM. Image 1 • The novel solid acidic ionic liquid polymer has been synthesized and characterized. • The solid acidic ionic liquid polymer showed high capacity in methyl esters production. • Maximum yield of methyl esters (91%) at 65 °C for 6 h with 400 rpm. • The process can generate biodiesel of high purity that meets the quality demands. [ABSTRACT FROM AUTHOR]

Ceramic proppants are preferred in hydraulic fracturing because of their high strength, good sphericity, and excellent acid corrosion resistance. Bauxite is the main raw material of ceramic proppants, but with the increasing depletion of bauxite resources, substitutes for bauxite need to be sought. Coal gangue is a solid waste that is rich in SiO2 and Al2O3, making it a potential substitute for the preparation of ceramic proppants. The use of coal gangue to prepare ceramic proppants can reduce the cost of ceramic proppants and benefit environmental protection. Studies on using coal gangue to prepare ceramic proppants have been conducted and achieved progress, but further improvement can still be obtained. Here, the basic principle, progress, and prospects of coal gangue ceramic proppants are reviewed. First, coal gangue ceramic proppants are divided into two categories, namely, proppants prepared using coal gangue as an auxiliary material and proppants prepared using coal gangue as the main material. Second, the progress of research of coal gangue ceramic proppants is summarized from the perspective of additives, and the influence of different kinds of additives on the sintering temperature and performance of proppants is discussed. Lastly, the future prospects of coal gangue ceramic proppants are presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mesoporous polymer ionic liquids for the immobilization of lipase demonstrated mesoporous properties. • Resultant systems were used as recyclable biocatalysts for ester production. • Lipase immobilization led to higher stability than that of the free enzyme. • The process can generate high-purity esters using lipase-immobilized mesoporous polymer ionic liquid. Herein, fatty acid esters were synthesized cost-effectively from various fatty acids using reusable lipase (L) immobilized with novel porous ionic polymer (PIP) (l –PIP). The functionalized mesoporous PIP was synthesized through Friedel–Crafts alkylation reaction of 1, 4-bis(bromomethyl) benzene in the presence of ferric chloride as catalyst, and lipase was completely immobilized with PIP at varied time, forming l –PIP–6 H , l –PIP–12 H , l –PIP–18 H , l –PIP–24 H , l –PIP–30 H , and l –PIP–36 H , which were applied in ester production. l –PIP–30 H was characterized using FT–IR, SEM, XPS, solid–state 13C NMR, and N 2 adsorption–desorption isotherms. The conversion of oleic acid reached 88.21 % under optimized conditions (12:1 ethanol/oleic acid molar ratio after 5 h at 45 °C with 250 wt% catalyst at 300 rpm). The stability and reusability of l –PIP–30 H were demonstrated by the sustained catalytic efficiency for at least six reaction cycles. Good catalytic activity during the esterification of various free fatty acids with ethanol was observed. This cost–efficient and effective lipase–immobilized PIP catalyst may have positive economic and environmental repercussions to inspire further academic and industrial research on biodiesel. [ABSTRACT FROM AUTHOR]

In China, a unique type of coal with extremely high aluminium (Al) content commonly occurs in the southern region of the Yinshan Oldland, Jungar Basin. The typical Al 2 O 3 content in the coal ash is ~ 45%, and exceeds 60% in some cases. This type of coal forms a league of its own and is named as ‘high-Al coal’. This high-Al coal, not only contains unusually high level of Al but also has high concentrations of Li, Ga, and REY (REE + Y). All these elements (i.e. Al, Li, Ga, REY) with high concentrations in this type of coal are very valuable source to various industries and therefor make perfect economic sense and add extra benefits into coal mines if they can be recovered by beneficiation processes. The mineral compositions in these coals mainly consist of kaolinite, boehmite, chlorite-group minerals, along with minor amounts of quartz, calcite, pyrite, siderite and amorphous clay materials. The Al and rare elements show different patterns of distribution and affinity relationships with organic and inorganic matter. The strong peraluminous granites and moyite from the Yinshan Oldland may be the main source of the Al and rare elements in the coals. Bauxite from the Benxi Formation may also be another source for the Al and rare elements in the coal of the Jungar coalfield. [ABSTRACT FROM AUTHOR]

In this study, B 4 C–TiB 2 composite ceramics with different TiB 2 contents sintered via hot pressing are processed into ceramic tools to turn AISI 4340 workpieces. Finite element analysis using the Deform-3D software is conducted to examine the effects of the cutting speed, depth of cut, and feed rate on the main cutting force and tool temperature of the B 4 C–TiB 2 ceramic tools. The wear mechanism is investigated through the microstructural analysis of the wear profile obtained after the turning experiments. Simulation results show that the B 4 C–30%TiB 2 ceramic tool demonstrates the best cutting performance. The optimal cutting parameters for the B 4 C–30%TiB 2 ceramic tool are a cutting speed of 300 m/min, depth of cut of 0.3 mm, and feed rate of 0.1 mm/r. The turning experiments reveal that the B 4 C–30%TiB 2 ceramic tool has a longer tool life than a commercially available YD tungsten carbide tool. The main wear forms of the B 4 C–30%TiB 2 ceramic tool are craters, chipping, and flank wear, and the wear mechanism can be attributed mainly to abrasive wear, adhesive wear, oxidative wear, and diffusion wear. This work can lay a theoretical foundation for the practical application of B 4 C–TiB 2 ceramic tools. [ABSTRACT FROM AUTHOR]

• The ionic organic polymeric materials fabricated with urea units are the efficient catalysts for the CO 2 fixation reaction. • The outstanding performance was attributable to the synergistic effect of bromine ion and urea units. • The kinetic experimental was studied and the activated energy was calculated as 48.5 kJ/mol. • A possible mechanism of the cycloaddition reaction catalyzed by ionic organic polymeric material of UIP-2 was proposed. Ionic organic polymeric materials are one of the most promising catalysts for the conversion of carbon dioxide (CO 2) to five-membered cyclic carbonates (5CCs). Herein, a series of urea functionalized ionic organic polymer materials UIPs (UIP-1, UIP-2 and UIP-3) have been prepared by condensation and Menshutkin reaction of three components in one-pot by solvothermal method. After characterization by FT-IR, SEM, 13C CP MAS NMR, TGA, N 2 adsorption and XPS spectroscopy, the UIPs were alternated as competitive catalysts for the CO 2 cycloaddition reaction with epoxides without metal and co-catalyst under solvent-free conditions. In particular, UIP-2, derived from 1,3,5-tribromomethyl benzene, 4-amino pyridine and 4,4′-diphenylmethane diisocyanate, demonstrated excellent catalytic activity in the CO 2 cycloaddition reaction with a high cyclic carbonate yield of 92.6 % under mild conditions: epichlorohydrin (ECH) (10 mmol), UIP-2 (0.10 mmol), reaction at 70 °C for 16 h with 1 bar of CO 2 , and the activated energy was calculated to be 48.5 kJ/mol. Furthermore, a possible catalytic mechanism was proposed by experiments and density functional theory (DFT) calculations. The ionic organic polymeric materials (UIPs) fabricated with urea units as activation sites showed excellent catalytic activity for CO 2 fixation reaction under mild conditions. The outstanding performance was attributable to the synergistic effect of nucleophilic bromine ion and urea unit as hydrogen bonding donor. [Display omitted] [ABSTRACT FROM AUTHOR]

A series of bis(pyridylcarbamate) ligands with the flexible diethylene glycol spacer and carbamate NH donors as catalysts have been designed and synthesized, and these can be used for the fixation of carbon dioxide with commercially sourced epoxides under mild conditions using alkali metal salts. It is worth noting that between the ligand and the alkali metal salt there is a synergetic effect, which plays an important role in accelerating the reaction rate. A detailed mechanistic insight into the effects of carbamate NH groups and the diethylene glycol spacer on the activation of the epoxides has been studied using density functional theory (DFT) methods. [ABSTRACT FROM AUTHOR]

• The novel solid acidic ionic liquid polymer has been synthesized and characterized. • Methyl esters from Jatropha curcas seed oil in a solid ionic liquid polymer one step process. • The process can generate methyl esters of high purity that meets the quality demands. • Kinetic of methyl esters has been investigated using Jatropha curcas with PILs. The objective of this study was to use n -hexane containing an ionic liquid for the extraction of oil and transesterification for the production of methyl esters from Jatropha curcas oil. A solid acidic ionic liquid polymer was synthesized using vinyl imidazole, 1,3-propane sultone, N , N -dimethylhexadecyl amine, allyl bromide, toluene, and the product was characterized by NMR and used for the transesterification. The optimum reaction conditions that resulted in the highest methyl ester yield of 94% were a J. curcas oil-to-dimethyl carbonate molar ratio of 1:5, a solid acidic ionic liquid polymer catalyst loading of 260 wt%, for 6 h with 500 rpm at 80 °C. Methyl esters were purified using celite powder and then analyzed by GC–MS. The activation energy and reaction rate constant were calculated from 4.862 to15.382 kJ/mol, and 0.389 to 4.602, respectively. The methyl esters met the quality standards defined under ASTM D6751-02. [ABSTRACT FROM AUTHOR]

• The concentration of residual state has increased in combustion products. • According to the enrichment index REI, hazardous elements can be classified into three categories. • The elements left in slag are Cr, Mn and Ni, the rest are semi-volatile. • The elements mainly volatilized into the atmosphere are few in the process of burning coal, only Sb. Trace elements in coal produce migration and enrichment after combustion, the enrichment and release of hazardous trace elements will cause effective harmful to human health and the environment. In this paper, the distribution characteristics and occurrence state of hazardous trace elements in coal combustion products were studied by measuring the concentration of harmful trace elements in coal, slag, coarse ash, fine and fly ash. The experimental study of step-by-step chemical extraction was carried out, the migration and transformation model of trace elements in coal combustion process was investigated. The results show that the trace elements are easily enriched in fine particles of coal ash. The occurrence state of elements in combustion products has changed obviously, and the concentration of residual state has increased for example aluminosilicates. According to the enrichment index REI (Relative Enrichment Index), hazardous elements can be classified into three categories: (I) The elements left in both solid waste slag and fly ash are Cr, Mn and Ni (REI > 0.85); (II) The elements left in solid waste are Be, Co, Cu, Zn, Cd, Ba, Pb and U (0.1 < REI < 0.85); (III) The elements mainly volatilized into the atmosphere are few, only Sb (REI < 0.1). [ABSTRACT FROM AUTHOR]

• Co-Salen complexes containing different groups and bearing potassium iodide (KI) complexed with crown ether (K@SCs) were prepared. • Salen derivative organic polymer as heterogeneous catalyst for CO 2 cycloaddition reaction. • Alkali metal halides and Lewis acids have good synergistic effects in catalytic reactions. Metallosalen presents very important applications in both homogenous and heterogeneous catalysis. Correspondingly, porous polymeric metallosalen combined with the performance of organometallics and heterogeneous polymers possess potential in CO 2 fixation reactions. Herein, a family collection of K@SCs were conceived and obtained by combining cobalt-salen complexes with different groups and diaminobenzene-18-crown-6 complexed with KI, which allows multiphase catalytic immobilization of CO 2 to epoxides. Catalyst K@SC-3 can fix CO 2 into a variety of substituted epoxides in >90% yields to the corresponding cyclic carbonates in co-catalyst-free and solvent-free conditions. Furthermore, K@SC-3 can be recovered and reused at least six times by simple centrifugal separation, demonstrating superior stability. The kinetics experiments were also carried out at varied temperatures catalyzed by K@SC-3. It is concluded that a first-order equation of epoxide was proved and the activation energy was calculated to be 27.13 KJ/mol. [Display omitted] [ABSTRACT FROM AUTHOR]

The catalyst of 6-O-(sulfobutyl)-β-cyclodextrin (SB-CD) is renewable, non-toxic, environmentally benign and biocompatible, which could be used as efficient and recyclable catalyst for the synthesis of biodiesel from free long-chain fatty acids with low-chain alcohols as substrates. The reaction was accomplished at 60°C for 1.5 h, while the products were separated from the catalyst system by liquid/liquid at room temperature with good conversion of 91-98%. The catalyst can be reused for 10 times. The novel and clean procedure offers advantages including short reaction time, good conversion, operational simplicity, and environmentally benign characteristics. [ABSTRACT FROM AUTHOR]

[Display omitted] • AuNPs-based colorimetric assay for rapid iohexol determination using 3-APBA-mediated aggregation. • Avoiding difficult and complicated functionalization process of AuNPs. • Good selectivity and low LOD for detecting iohexol. • Comparable precision and accuracy to the LC-DAD method for both environmental and biological samples. Iohexol (IHO), as one of iodinated X-ray contrast, is often used as not only a chemical marker for tracking wastewater contamination in aquatic environment, but also an ideal glomerular filtration rate marker for explorating kidney disease. To these aims, it is important to establish reliable, fast, and cheap methods to detect IHO in environmental and biological samples. This work describes for the first time the development of a selective, sensitive and reliable colorimetric sensing assay for the fast determination of IHO in environmental and biological samples based on 3-aminophenylboronic acid (3-APBA) mediated aggregation of gold nanoparticles (AuNPs). In this approach, 3-APBA can assemble on the AuNPs surface through electrostatic interaction between its amino groups with the negatively charged citrate stabilizer of AuNPs to form AuNP@3-APBA. Subsequently, the aggregation and visual color change of the assembled AuNP@3-APBA are induced by the covalent reaction between boronic acid ligands of 3-APBA and cis -diols of IHO. The developed assay presented a very simple operating procedure and a rapid analysis time of around 10 min. The developed assay also exhibited good selectivity and a low limit of detection (LOD) of 0.005 mM for detecting IHO. Moreover, the developed assay showed comparable accuracy and precision to the high-performance liquid chromatography-diode array detector (HPLC-DAD) method when used for the rapid determination of IHO in river water and human urine samples. The recoveries of IHO at three spiking levels were in the range of 91.5–106.3% with relative standard deviation (RSD) values below 6.39%. [ABSTRACT FROM AUTHOR]

New suites of sulfonic acid-functionalized microporous ionic polymers (PIPs) catalysts were synthesized with polymer, alkyl bromides, and 1, 3-propane sultone via a two-step procedure. The synthesized microporous PIP catalysts were characterized using FT-IR, SEM-Mapping, XPS, N 2 adsorption–desorption isotherms, solid NMR spectroscopy, and element analysis. Esterification of several fatty acids with ethanol, which was used as a model reaction in the stabilization of Jatropha curcas seed oil, was checked over functionalized PIP. We tested the catalytic performance of PIP-C 8 on the synthesis of fatty acid esters via the transesterification of J. curcas seed oil with a mixture of short-chain alcohols such as ethanol, ethanol–to–diethyl carbonate (1;1 molar ratio), and ethanol–to–dimethyl carbonate (1:1 molar ratio) with 170 mg of PIP-C 8 at reflux temperature with agitation. The PIP-C 8 catalyst was particularly effective, having achieved yields of 85%, 94%, and 70% for J. curcas seed oil with ethanol, J. curcas seed oil with ethanol–to–DEC, and J. curcas seed oil with ethanol–to–DMC, respectively, under the optimized reaction conditions. The catalyst could be recycled more than five times without significant deactivation. Kinetic studies performed at different temperatures revealed that the conversion of oleic acid to an ethyl ester follows a first-order reaction. The best catalysts with microporous structure (average pore diameter: 1.7–1.9 nm, pore volume: 0.23–0.33 cm3 g–1) and –SO 3 H density (0.70–0.84 mmol/g cat) were obtained by 1, 3-propane sultone of the chemically activated. The results indicate that the site activity of functionalized microporous ionic polymer materials shows promising approach for the development of environmentally friendly technology. [Display omitted] • A novel, efficient and recyclable microporous ionic polymer (PIPs) catalyst was synthesized. • The catalytic activity, stability, and recyclability of synthesized microporous PIP was examined. • Microporous PIP catalyst yield excellent FFA tolerance level. • Microporous PIP catalyst exhibit promising results for FFAs esterification and Jatropha curcas oil transesterification. [ABSTRACT FROM AUTHOR]

A new series of acidic, dendrimeric polyamidoamine based polymeric ionic liquids of [PAMAM 3256 C n were synthesized with a second generation polyamidoamine dendrimer, alkyl bromides and 1, 3-propane sultone via a two-step procedure. The structure of functional ionic liquids was characterized by Fourier-transform infrared spectroscopy, nuclear magnetic resonance spectroscopy. The polyamidoamine -1- dodecyl [PAMAM 3256 C 12 catalyst was used for green fuel production via the transesterification of yellow grease. The influence of reaction variables on the green fuel yield was studied using this catalyst. The catalyst was effective having achieved a 93% green fuel yield from yellow grease after 6 h of reaction at 65 °C, using 306.8 mol (10 mmol) (wt % based on molar concentration of lipids) of [PAMAM 3256 C 12 catalyst, a yellow grease-to-methanol molar ratio of 1:20 with a constant agitation speed 800 rpm. The catalyst was showed excellent stability for yellow grease transesterification over four cycles. Additionally, catalysts showed excellent transesterification activity of Jatropha curcas , Ricinus communis , and Pistacia chinensis oil, with green fuel yields of 90, 91, and 92%, respectively. The properties of green fuel were met the ASTM D6751-02 standards. Results indicate that the [PAMAM 3256 C 12 catalyst system shows promising potential as a viable industrial-scale alternative. Image 1 • A high green fuel conversion of 93% along with recyclability was obtained. • We examined the catalytic activity, stability and reusability of the [PAMAM 3256 C 12 catalyst. • Characterization was performed explaining the catalyst structure, stability and activity. • The process can generate high purity green fuel that meets the quality demands. [ABSTRACT FROM AUTHOR]

Today wildfire is an important disturbance in many continental ecosystems, and it is assumed that with ongoing climate changes the frequencies and impacts of wildfires will increase in many regions. One way to obtain information about the potential long term influences of wildfires on ecosystems and the climate system itself is to study palaeo-wildfires. A total of 140 Jurassic samples, including 122 coal samples and 18 rock samples from roof and floor of coal seams, were collected from 4 coalfields in Northwestern China. The samples were analyzed by macropetrography, microscopy, scanning electron microscopy, gas chromatography, and gas chromatography–mass spectrometry to study the evidences of wildfires and their impact on the paleoclimate. High contents of pyrogenic inertinites (charcoal), natural char and natural coke particles observed in the samples which indicate that widespread wildfire events occurred in the early Middle Jurassic in all over Northwestern China. Additionally, high-molecular-weight polycyclic aromatic hydrocarbons were detected in the coal samples. These aromatic compounds were formed under high temperature and provide further evidence of wildfires. According to a carbon emission model for modern forest fires, the total carbon and gas emissions from wildfires in peat swamps of the Middle Jurassic in Northwest China were calculated by the data from 21,575 coal samples of number of 1567 drill core samples. The total carbon released from peat-swamp forest wildfires was at least 1207 Gt, corresponding to emissions of CO 2 , CO and CH 4 of 1926 Gt, 163 Gt, and 8.8 Gt, respectively. The huge amount of CO 2 released by forest fires in the peat swamp systems of the Middle Jurassic in Northwestern China alone was equivalent to 64.20% of the total CO 2 in the atmosphere at present (3000Gt). The large amounts of greenhouse gases released by wildfires must have led to long-term changes in the atmospheric composition and have caused global warming, which could have the reason of affected the paleoclimate. • High contents of charcoal indicate that wildfire events occurred in the early Middle Jurassic. • The main types of wildfires were surface fires and ground fires, with less crown fires. • The oxygen levels could have reached from 27% to 29% in the Middle Jurassic. • The greenhouse gases released by wildfires in the Middle Jurassic in Northwest China reached at least 2097.6 Gt • Greenhouse gases released by wildfires might have affected the paleoclimate and paleoecosystems. [ABSTRACT FROM AUTHOR]

The Dongying depression is an important oil-producing area in northeastern China, where the Paleogene Shahejie Formation is the main oil-bearing feature. Although petroleum migration and accumulation in the Dongying depression have been extensively studied, the charging history is still unclear. This paper defines the timeframe of petroleum migration on the basis of a comprehensive investigation of fluid inclusions coupled with basin modeling. According to the petrography and microthermometry of the fluid inclusions, types of fluid inclusion with low-peak-range distributions of the homogenization temperature (T h) (85–95 °C for the Niuzhuang sag and 90–105 °C for the Lijin sag) and high-peak-range T h distributions (105–120 °C for the Niuzhuang sag and 115–130 °C for the Lijin sag) were identified. By recovering the burial and thermal histories of Niuzhuang and Lijin sags with pressure–volume–temperature–composition simulation and one-dimensional basin modeling, it can be inferred that the trapping pressures of two types of hydrocarbon inclusions were higher than the corresponding paleopressure. (42.4 and 42.0 MPa, respectively), indicating rapid hydrocarbon charging resulting from abnormally high pressure. Two hydrocarbon charging events associated with the regional tectonic evolution of the Dongying depression, namely, continuous deposition and tectonics in the Paleogene Dongying Formation (Ed) and rapid deposition and tectonics in the Paleogene Minghuazhen Formation (Em), were inferred. The direction of oil charging was traced from the center to the margin in the north, and from the center to the central fault in the southeastern part of the depression in general, as indicated by the molecular maturity parameters, which roughly coincided with the abnormal pressure. • The investigation of fluid inclusions showed two oil-charging episodes in Sha 3 reservoirs. • The basin modeling suggested each reservoir was charged during the Late Paleogene and Early Neogene respectively. • The oils are charged along with the central faults and from the center to the edge of the depression. [ABSTRACT FROM AUTHOR]

• The PEI 10000 C 12 polymer ionic liquid was selected as the most efficient catalyst. • The mechanism of polymer ionic liquid catalyzed esterification/transesterification was clarified. • An emerging, efficient and green technology for ethyl ester production was developed. • Kinetics of ethyl esters has been investigated using Pistacia chinensis with polymer ionic liquid. • We examined the catalytic activity of structure and reusability of polymer ionic liquid. A novel solid acidic polymeric ionic liquid catalyst was synthesized for ethyl esters production via the esterification of oleic acid with ethanol, normally transesterification of Pistacia chinensis oil with diethyl carbonate. Gas chromatography-mass spectroscopy analysis was used to characterize the products and optimize the reaction conditions to provide P. chinensis oil derived ethyl esters in 93% yield. Kinetic studies performed at different temperatures revealed that the conversion of P. chinensis oil to an ethyl ester follows first order reaction kinetics. The properties of ethyl esters were determined, found to meet the ASTM D6751-02. Results revealed that the catalyst had perfect utility after several runs without much loss in activity. The mild conditions (1:5) P. chinensis oil:diethyl carbonate molar ratio, 300 wt% PIL loading, 120 °C, 400 rpm, 6 h, recyclability of the catalyst make the proposed synthesis a sustainable method for the development of ecofriendly, cost-effective biofuels. [ABSTRACT FROM AUTHOR]

This paper provides new geochemical data focusing on valuable elements in the coal, parting, and floor samples in the No. 5 coal seam of the Taiyuan Formation from the Wujiawan mine, Datong coalfield, northern China. The minerals mainly consist of kaolinite, calcite, and pyrite, as well as trace amounts of quartz and illite. The No. 5 coal is enriched in Li, Ga, high field strength elements (HFSEs), and rare earth elements and yttrium (REY) when compared with world hard coals. Of particular interest is the high average concentration of Li (67.66 μg/g), which is around seven times higher than the value for world hard coals. Lithium, Ga, and HFSEs have strong inorganic affinities, whereas REY have organic affinities. The main carrier of Li, Ga, and HFSEs is aluminosilicate minerals, while REY appear to occur with organophosphorus. These HFSEs are enriched, both in the parting and in the adjacent coal samples. This suggests that these elements are likely to leach out during the diagenetic process. The distribution patterns of REY, along with the ratio of Al2O3/TiO2 and the figure of Zr/TiO2 vs. Nb/Y are suggestive of their derivation from felsic parent material. In the northern and eastern part of the Datong coalfield, there are several regions where the Li content is higher than the mineable grade, in particular in the northern Datong coalfield where there is a mine with an Li content of 294.6 μg/g. This is significantly higher than the mineable grade. Therefore, there is a potential for financially viable recovery of Li in these coals of the Datong coalfield. [ABSTRACT FROM AUTHOR]

The Chang 6, Chang 8, and Chang 9 reservoirs of the Upper Triassic Yanchang Formation in the Zhenjing area of the Ordos Basin are characterized by low porosity, low permeability, high oil saturation, and large oil reserves, which indicate huge tight oil potential. To comprehensively investigate the hydrocarbon contributors and charging history, fluid inclusions were systemically studied coupled with basin modeling and oil geochemical analysis. According to the petrographic characteristics, two episodes of fluid inclusions occurred in each of the three reservoirs. Microthermometry analysis suggests that the hydrocarbon inclusions of the first episode in each reservoir are distributed mainly along overgrowth quartz or secondary microcracks and exhibit light yellow or light brown fluorescence; the coeval aqueous inclusions display low homogenization temperature (Th) peaks with 80–100 °C. The hydrocarbon inclusions of the second episode in each reservoir are mainly distributed in microcracks that cut across or within quartz grains and exhibit light green or bluish-green fluorescence; the coeval aqueous inclusions are characterized by high Th peaks with 110–120 °C. The different characteristics of the two episodes of the fluid inclusions imply the existence of two episodes of hydrocarbon charging events. The burial and geothermal histories of the various reservoirs were reconstructed using one-dimensional basin modeling and pressure–volume–temperature–composition (PVTX) simulation coupled with the authigenic illite K–Ar dating. The reconstruction implied the time of the two hydrocarbon charging episodes to be Early Cretaceous and Late Cretaceous. Oil-source correlation studies illustrate that the Chang 6, Chang 8, and Chang 9 crude oils all originate from the Chang 7 source rock. The migration characteristics and directions were comprehensively analyzed by using maturity parameters. This explanation of the charging history and oil migration pathway of the Upper Triassic Yanchang Formation in the Zhenjing area provides a theoretical basis for further exploration. • Each reservoir was charged during the Early and Late Cretaceous, respectively. • The crude oils in all reservoirs originated primarily from the Chang 7 source rocks. • The oils are charged along with the faults and the W-dipping monocline. [ABSTRACT FROM AUTHOR]