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A low-rank coal was subjected to deoxygenation using NiO/Mo2O3-ZSM-5 as the catalyst and ethanol as the solvent under pressurized hydrogen circumstance to acquire a catalytic product (CP). Another parallel reaction was repeated with the same procedure but with nitrogen circumstance and without the catalyst to obtain a non-catalytic product (NCP). Both CP and NCP were analyzed with a Fourier-transform infrared spectroscopy, a gas chromatography/mass spectrometer (GC/MS) and an Orbitrap mass spectrometer (Orbitrap MS) to understand the deoxygenation features of low-rank coal. Low polar and molecular mass compounds were detected in NCP and CP using GC/MS. Compared with GC/MS, more species and high polarity were identified in NCP and CP by Orbitrap MS. The three analytical techniques indicated the effective oxygen removal during the catalytic treatment and provide a comprehensive evaluation of the deoxygenation process. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Dayan lignite was subjected to thermal dissolution sequentially with cyclohexane, acetone, and methanol. Each thermal dissolution extract was subjected to further separation/enrichment using column chromatography, which was sequentially eluted with petroleum ether, a mixture of ethyl acetate and petroleum ether (vol:vol = 1:1), and ethyl acetate. The three thermal dissolution extracts and nine enrichment subfractions were characterized by an Orbitrap mass spectrometry equipped with an atmospheric pressure chemical ionization ion source. The mass spectrometry data were also statistically analyzed by principal component analysis, which can reduce the dimensionality of data and classify multiple samples according to principal components. Identified compounds in the extracts and subfractions are classified into eight classes according to the heteroatom distribution. Hydrocarbon class is mainly presented in the petroleum ether fraction, and oxygen class, nitrogen class, and oxygen‐nitrogen class are distributed in both petroleum ether/ethyl acetate and ethyl acetate subfractions. The combination of different analytical methods enhances the understanding of coal at the molecular level and provides important data for downstream refining processes. [ABSTRACT FROM AUTHOR]

An active and novel magnetic difunctional solid superbase catalyst Ni‐Mg2Si/attapulgite powder (AP) was prepared by thermally decomposing nickel tetracarbonyl onto the as‐synthesized Mg2Si/AP followed by impregnating Mg2Si onto AP in CCl4 and characterized by multiple analyses. It was also successfully used in the catalytic hydroconversion (CHC) of coal‐related model compound oxybis (methylene) dibenzene (OBMDB) and an extract (E) from Piliqing subbituminous coal (PSBC) in n‐hexane. As a result, OBMDB was completely converted to methylcyclohexane by the CHC under 3 MPa of initial hydrogen pressure at 240 °C for 2 h. Ni‐Mg2Si/AP can activate H2 to biatomic active hydrogen (H...H) and split H2 to immobile H+ attached on the Ni‐Mg2Si/AP surface and relatively mobile H−. Then the bridged linkage (BL) in OBMDB can be cleaved by H− attack on a α‐carbon atom in OBMDB, producing toluene and benzyloxy anion, which abstracts H+ from the Ni‐Mg2Si/AP surface to afford phenylmethanol (PM). The α‐carbon in PM is attacked by H‐ to generate toluene and HO−. H...H transfers to benzene ring in toluene yields methylcyclohexane. The soluble portion (SP) from the CHC (SPE‐CHC) and non‐CHC (NCHC) (SPE‐NCHC) of E were analyzed with a gas chromatograph/mass spectrometer and Fourier transform infrared spectrometer. Non‐substituted cycloalkanes (NSCAs) are predominant in the SPE‐CHC, accounting for 66.9 % of the total group components, and interestingly 65.3 % of NSCAs is cyclohexane, while non‐substituted arenes are the most abundant in the SPE‐NCHC. The results indicate that the CHC is beneficial to the fracture of COCBB and hydrogenation of ARs to produce more NSCAs. [ABSTRACT FROM AUTHOR]

A series of carbon disulfide/acetone mixtures were used to extract organic species from Shengli lignite, a Chinese coal. Orbitrap mass spectrometry coupled with electrospray ionization was used to characterize the molecules in the extracts. Heteroatomic species, including oxygenates, nitrogenates, and sulfonates, were determined. Pure carbon disulfide or acetone had the lowest extraction for oxygenates while the mixtures increased the relative abundance of oxygenates. From the value of the double bond equivalence, the compounds with 1 oxygen contained the highest concentrations of aromatics and aliphatics, but compounds with 6 were aliphatic with a double bond equivalence of 3. For compounds containing 2 oxygens, aromatics with one ring were present at the highest concentrations in the 1:1 carbon disulfide:acetone extract. For compounds containing 3, 4, and 5 oxygens, most aromatic species were identified with double bond equivalence values between 4 and 6, showing the presence of an aromatic ring. The results indicated that the solvent mixtures enhanced the extraction of oxygenates from Shengli lignite. [ABSTRACT FROM PUBLISHER]

Highlights • A method to evaluate the bias of three MS ionization methods was proposed for coal. • Elemental compositions obtained from ultimate analysis was set as a reference. • Elemental compositions derived from APCI-MS showed closer values to ultimate analysis. • Adjusted compound classes offer a closer measurement to the actual values. Abstract The relative abundances of compound classes (e.g. CHO 1 , CHO 2 and CHNO 1) in fossil fuels have been widely used in previous researches based on the data from mass spectrometry (MS). However, such observations are susceptible to the ionization bias of MS due to the variation of ionization efficiency, which may affect the downstream quantitative analysis. Many efforts have been devoted to investigating the ionization efficiencies of a variety of model compounds, but not complex and diverse mixtures. Therefore, it is necessary to investigate how quantitatively ionization bias affects the MS analysis of complex mixtures. In this study, ionization bias was preliminarily investigated by comparing the elemental compositions obtained from MS-analysis via different ionization methods with the data acquired by a standard elemental analyzer. A coal-derived liquid and mixtures of five model compounds were ionized by atmospheric-pressure chemical ionization (APCI), electrospray ionization or direct analysis in real-time, followed by analyzing using a high-resolution Orbitrap MS to obtain elemental compositions. MS-based results via APCI ion source showed the closest elemental compositions to those obtained from the elemental analyzer. For the MS-based analysis, the abundances of S- and O-containing compounds were significantly lower and that of N-containing compounds was clearly higher compared to ultimate analysis. The abundances of compound classes were adjusted to provide a closer approximation of the actual contents, which might better serve for the downstream quantitative analysis. Although absolute quantification still needs additional work, the adjusted MS-based analysis provides not only the molecular level data, but also a better quantification ability compared to previous analytical approaches. [ABSTRACT FROM AUTHOR]

Highlights • HCA and EMGM are introduced to reach in-depth statistic results for coal extracts. • The similarities and differences of clusters are visually exhibited in a plot via HCA. • Molecular structures in the same EMGM model have a certain similarity. Abstract A coal was extracted and thermally dissolved with cyclohexane, acetone and methanol sequentially. The ultrasonic extracts and thermal dissolution (TD) products were analyzed using an Orbitrap mass spectrometer (MS) with an atmospheric pressure chemical ionization source in positive ion mode. Large amounts of MS data were obtained but there were challenges in obtaining meaningful information from the data. The purpose of cluster analysis is to reduce complex multivariate data into meaningful groups. Two cluster analysis methods, hierarchical cluster analysis and expectation maximum algorithm based on Gaussian mixture model (EMGM), run by R language were introduced to obtain in-depth statistical results for compounds in both extracts and TD products. Seven types of heteroatomic compounds (O 1 , O 2 , N 1 , S 1 , O 1 N 1 , O 1 S 1 and N 1 S 1) in the extracts under the condition of ultrasonic extraction with cyclohexane were clustered with EMGM and possible structures of the related models can be inferred by analyzing the relationship between carbon number and double bond equivalent. The application of cluster analysis will provide methodological guidance in studying the structure of coal molecules. [ABSTRACT FROM AUTHOR]

Highlights • Fragmentation patterns of 22 model compounds with varied energies were discussed. • The optimal collision energy to investigate aromatic core structures should be 80 eV. • Energy-resolved ISCAD showed potential for in-depth structural analysis of coal/biomass. Abstract In-source collision activated dissociation (ISCAD) is an effective method to obtain molecular structure of coal and biomass and provide basic knowledge for coal/biomass conversion. Twenty two coal/biomass-based model compounds and one coal extract were studied via ISCAD to understand the relationship between collision energy and molecular structure and the application of ISCAD in the characterization of coal. Model compounds showed different fragmentation patterns with the increase of collision energy and the detailed fragmentation pathways in context of collision energies were proposed. According to the ISCAD results of coal extract, the weighted mean molecular weight (MW) and weighted mean double-bond equivalent (DBE) values of ionized coal molecules decreased over collision energy of 80 eV. The decrease of weighted mean MW and DBE were mainly caused by the cleavage of alkyl chains, bridged bonds, and minor cracking of small aromatic cores from precursor ions upon fragmentation. Therefore, the optimal ISCAD collision energy for the investigation of aromatic core structures of the coal extract should be around 80 eV. [ABSTRACT FROM AUTHOR]

Dayan lignite (DL) was subjected to thermal dissolution sequentially with cyclohexane, acetone and methanol to obtain three filtrates. The filtrates were characterized by Fourier transform infrared spectroscopy, gas chromatography/mass spectrometry (GC/MS), and time-of-flight mass spectrometry (TOF-MS) equipped with atmospheric pressure photoionization (APPI), electrospray ionization (ESI) or direct analysis in real time (DART) to understand the structural features of DL. Aliphatic hydrocarbons, furans and alcohols were enriched in the filtrate of cyclohexane, acetone and methanol, respectively, according to the data of GC/MS. One ring aromatics was also identified by GC/MS as major species in the three filtrates. Both GC/MS and APPI-MS can well analyze compounds with low polarity, but APPI-TOF-MS in this work successfully characterized polycyclic aromatics and extended the measurement range (molecular weight and ring size) of GC/MS. ESI-TOF-MS is suitable to analyze polar compounds in coal. Data from ESI-TOF-MS indicated that heteroatom compounds including non-aromatics and aromatics with 1-2 rings are the major polar components in DL. As an ambient MS ionization method, DART shortened the analysis time without sample pretreatment and more aromatics over 4 rings were identified by DART-TOF-MS. Characterization of the complex coal filtrates with multiple mass spectrometers provided a full view of the molecular information of DL. [ABSTRACT FROM AUTHOR]

Two Chinese coals, Shengli lignite and Shenmu–Fugu subbituminous coal, were subjected to non-catalytic hydroconversion (NCHC) and catalytic hydroconversion (CHC) in cyclohexane at 300 °C for 3 h under pressurized hydrogen using a solid acid as the catalyst, which was prepared by impregnating isometric pentachloroantimony and trimethylsilyl trifluoromethanesulfonate into an activated carbon. The reaction mixtures from both NCHC and CHC were sequentially extracted with petroleum ether, carbon disulfide, methanol, acetone, and isometric acetone/carbon disulfide mixed solvent to afford extracts 1–5 (E 1 –E 5 ). The results show that both E 1 and total extract yields from CHC are appreciably higher than those from NCHC of each coal. E 1 from either NCHC or CHC of each coal was analyzed with a gas chromatograph/mass spectrometer (GC/MS) and an atmospheric solids analysis probe/time of flight mass spectrometer (ASAP/TOF-MS). GC/MS analysis shows that each E 1 consists of alkanes, arenes, and oxygen-containing organic compounds (OCOCs), and most of the arenes are methyl-substituted ones, whereas alkenyl groups only appear on benzene ring; most of the OCOCs are arenols, especially alkylarenols. According to ASAP/TOF-MS analysis, organic compounds with molecular masses ranging from 500 to 950 u appear in E 1 from CHC of both coals. [ABSTRACT FROM AUTHOR]

• Ni-Mg 2 Si/AP is active for catalyzing AR hydrogenation and >C ar O cleavage. • Oxydibenzene was completely converted to cyclohexane at 150oC. • Oxydibenzene conversion is 91.2 % over Ni-Mg 2 Si/AP even recycled 4 times. Ni-Mg 2 Si/attapulgite powder (AP) was prepared by thermally decomposing nickel tetracarbonyl onto the as-synthesized Mg 2 Si/AP by impregnating Mg 2 Si onto AP in CCl 4. Its catalytic performance was evaluated by the catalytic hydroconversion (CHC) of oxydibenzene (ODB) in n -hexane under different reaction conditions. Both ODB conversion and cyclohexane selectivity are 100 % by the CHC of ODB over Ni-Mg 2 Si/AP under 3 MPa of initial hydrogen pressure at 240 °C for 4 h. However, almost no ODB was converted without Ni-Mg 2 Si/AP under the same conditions. The results show that Ni-Mg 2 Si/AP could activate H 2 to biatomic active hydrogen (H⋯H) and H−, resulting in the hydrogenation of aromatic rings (ARs) and the hydrocracking of >C ar O bridged bonds (COBBs), respectively. Additionally, the catalyst was also successfully applied in the CHC of extraction residue (ER) from Piliqing subbituminous coal (PSBC) in n -hexane. The group components of the soluble portion (SP) from CHC and non-CHC (NCHC) (SP CHC and SP NCHC) of ER were analyzed with a gas chromatograph/mass spectrometer. The yield (36.4 %) of SP CHC is significantly higher than that (1.8 %) of SP NCHC. More alkyl-substituted arenols (ASAs), anisoles, and methoxy-substitued cresols exist in SP NCHC , while SP CHC contains more normal alkanes (NAs), non-substituted cycloalkanes, alkylcyclohexanes, tetralins, and octahydroanthracenes. NAs are predominant in SP CHC , while ASAs are the most abundant in SP NCHC , indicating that the CHC facilitates the hydrocracking COBBs and hydrogenating ARs. ODB conversion is as high as 91.2 % after recycling 4 times. Therefore, the catalyst might be potential to produce coal-derived chemicals and clean liquid fuels to facilitate coal efficient conversions owing to its high activity, difunctionality, stability, and good recyclability. [ABSTRACT FROM AUTHOR]

Three low-rank coals were subjected to a thermal dissolution (TD) process sequentially using cyclohexane (CYH) and methanol (MeOH) solvent to obtain six TD extracts. The six TD extracts were analyzed by Fourier transform infrared spectroscopy (FTIR), gas chromatograph/mass spectrometry (GC/MS) and gas chromotography/quadrupole time-of-flight MS (GC/Q-TOF MS) to understand the compositional features of three low-rank coals. Hierarchical clustering analysis (HCA) and principle component analysis (PCA) were applied to show the relationships among 10 classes in the six TD extracts. Compared with GC/MS, a routine analytical method, more species with relative high molecular mass and more oxygen-containing organic compounds (OCOCs) were determined using GC/Q-TOF MS. In addition, HCA dendrogram and heatmap reveal the difference among 10 classes in the TD extracts. Meanwhile, the distributional and compositional features of six TD extracts were also exhibited in the score plot and loading plot of PCA. [ABSTRACT FROM AUTHOR]