Yun-Peng Zhao

Synergic effect of methanol and water on pine liquefaction

Pine liquefaction (PL) and re-liquefaction of its liquefaction residues in sub- and supercritical methanol, water or methanol/water mixed solvents (MWMSs) was investigated. The results show that isometric MWMS has the highest synergic effect on PL. Moreover, the total yield of bio-oil (BO) and conversion from pine and its residue both liquefied in the MWMS were obvious higher than those from PL in methanol (water) and re-liquefaction of its residue in water (methanol), suggesting that the interaction between the two solvents is responsible for synergic effect. This approach facilitates understanding the mechanism for biomass liquefaction in mixed solvents and developing efficient utilization process of biomass.

Analysis of Geting Bituminous Coal by Electrospray Ionization and Direct Analysis in Real Time Mass Spectrometry

Understanding the structure and composition of coals is important for effective, clean, and value-added utilization. In addition to gas chromatography/mass spectrometry which is commonly used to analyze coal, mass spectrometry (MS) may be used with other ion sources such as electrospray ionization (ESI) and direct analysis in real time (DART) for characterization. In this work, Geting bituminous coal was extracted sequentially and exhaustively with petroleum ether, carbon disulfide, methanol, acetone, an isometric acetone/carbon disulfide mixture, tetrahydrofuran, and an isometric tetrahydrofuran/carbon disulfide mixture. Raw coal, extracts, and the extraction residue were analyzed using MS equipped with ESI or DART. Organic heteroatomic species in the extracts were determined by liquid chromatography-mass spectrometry equipped with ESI. Molecular weight distributions of organic species in raw coal, extracts, and extraction residue were characterized by ESI-MS and DART-MS. Associated molecules and homologous compounds in coal extracts were identified.

Characterization of humic acids extracted from a lignite and interpretation for the mass spectra

Humic acids obtained from a Chinese lignite via alkali treatment were analyzed using Fourier transform infrared spectroscopy and Orbitrap mass spectrometry coupled with an electrospray ion source (ESI-Orbitrap-MS). Raw coal and the corresponding residue were characterized via scanning electron microscopy and energy dispersive spectrometry. Over 4700 heteroatom-containing compounds with wide distributions of molecular mass and unsaturation degree were detected via the ESI-Orbitrap-MS, and around 60 percent of the detected species were found to be oxygen-containing compounds. In addition, van Krevelen diagram and double-bond equivalent (DBE) plot were introduced to provide more structural details of the compounds. For the species only containing C, H, and O (HACHO), condensed aromatic compounds with a DBE value over 20 only contained 1 or 2 oxygen atoms. Carboxyl- and hydroxyl-containing aliphatic compounds (CHCACs) were predominant in HACHO with 5 or 6 oxygen atoms. Both the CHCACs and aromatic carboxylic acids or phenols were grouped into clusters in the van Krevelen diagram to be recognized. The introduction of a nitrogen atom to the HACHO species was based on the structures of the HACHO species, which is also indicated by the van Krevelen diagram.

Sequential ultrasonic extraction of a Chinese coal and characterization of nitrogen-containing compounds in the extracts using high-performance liquid chromatography with mass spectrometry.

Dongming lignite was sequentially extracted with petroleum ether, carbon disulfide, methanol, acetone, and isometric carbon disulfide/acetone mixed solvent at room temperature to afford extracts 1-5, respectively. High-performance liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry was used to separate and characterize heteroatomic species in the extracts at molecular level. Molecular mass of compounds in the extracts is mainly distributed from 300 to 800 u, and the relative abundance of compounds with molecular mass over 800 u in the carbon disulfide extract is 135 times of that in the petroleum ether extract. The acetone extract has the highest relative abundance for organonitrogen compounds. Double bond equivalence numbers of detected species indicate that most of the organonitrogen compounds contain N-heterocyclic aromatic rings, including pyridine, quinoline and pyrrole. Some organonitrogen isomers in Dongming lignite were separated and identified by high-performance liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry, and the corresponding structural information was proposed.

Evaluation of the Oxidation of Rice Husks with Sodium Hypochlorite Using Gas Chromatography-Mass Spectrometry and Direct Analysis in Real Time-Mass Spectrometry

Rice husk powder was oxidized in aqueous sodium hypochlorite solution under mild conditions with different reaction times. Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry (GC-MS), and direct analysis in real time-mass spectrometry (DART-MS) were used to analyze the oxidation products. Results showed that oxidation was a feasible way to depolymerize the macromolecules in the biomass and convert hydroxyl groups to carboxyl groups. In total, 113 organic compounds in oxidation products with molecular mass less than 500 Da were identified using GC-MS. As an ambient ionization technique, DART-MS was applied to the determination of biomass derivatives and revealed mass distribution and molecular structure information for the rice husk oxidation products.

Characterization of a Chinese lignite and the corresponding derivatives using direct analysis in real time quadrupole time-of-flight mass spectrometry

Direct analysis in real time (DART) ionization technique coupled with a quadrupole time-of-flight mass spectrometry (Q-TOF MS) with high resolving power was applied to characterize raw coal and coal derivatives in the solid state. Desorption and ionization under optimized parameters allowed for the detection of small molecules scattered inside pores of a macromolecular network of raw coal. Use of the second-stage MS (Q-TOF) significantly contributed to the structural elucidation of compounds in coal and coal derivatives.

Air classification of moist raw coal in a vibrated fluidized bed

Abstract The principle, characteristics, pilot testing, and applications of a new sizing technology for moist raw coal were described. This new technology is completely different from the traditional screening in principle. It extracts fine coal from coarse coal by entrainment of an ascending airflow in a vibrated fluidized bed. It has no aperture-blinding problem at all. The classification efficiencies varied from 74.85% to 93.84% for classification at cut-size of 6, 3, 2, 1, or 0.5 mm when the free moisture of coal was in the range of 1.7–9.5%. The ash contents of fine coal products obtained from air classification were 2–3% lower than those of the same size fractions in feed for most cases, which is beneficial to producing lower ash fine coal from raw coal for blast furnaces or pulverized coal firing boilers. The new technology provides a practical solution to the difficult task of sizing moist raw coal at cut-size below 6 mm. It has found wide applications in coal processing and generated considerable economic and environmental benefits.

Analysis of the Products from the Oxidation of Geting Bituminous Coal by Atmospheric Pressure Photoionization–Mass Spectrometry

Geting bituminous coal was directly oxidized in aqueous sodium hypochlorite. The reaction mixture was sequentially extracted with ethyl ether and ethyl acetate. Both extracts were esterified with diazomethane to obtain methyl esterified products, which were analyzed using high performance liquid chromatography–mass spectrometry with electrospray ionization or atmospheric pressure photoionization. A large number of low- and nonpolar products with relatively high molecular masses were determined using atmospheric pressure photoionization mass spectrometry. Toluene and a toluene/anisole mixture (vol/vol = 95:5) were added to the atmospheric pressure photoionization system as dopants. Toluene induced better ionization than the toluene/anisole mixture in both ion signal intensity and number of detected species. Most of the molecular associated compounds contained heteroatoms.

Characterization of Oxygenates, Nitrogenates, and Sulfonates in Shengli Lignite Extracts by Orbitrap Mass Spectrometry

ABSTRACT 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.

Enrichment and analysis of long-chain normal alkanals from Zhundong subbituminous coal

Abstract Zhundong subbituminous coal was exhaustively extracted with isometric carbon disulfide (CDS) and acetone mixed solvent. The extract was fractionated with petroleum ether (PE) and CDS into PE-extractable portion (E1) and CDS-extractable portion (E2). E2 was sequentially eluted with PE and 30% CDS/PE mixed solvent through a silica gel-packed column. A series of long-chain normal alkanals (LCNAs, C18−27) were enriched from E2 and identified with a gas chromatography/mass spectrometer. The fractional extraction and subsequent column chromatography provide an effective approach for enriching LCNAs from middle- and low-rank coals. LCNAs could be a class of important biomarkers.