Methanol-soluble Portion Research Articles

Pretreatment with Trichoderma sp. AH promotes directional conversion of organic nitrogen compounds in supercritical methanolysis of wheat straw

The specificity and conversion of supercritical methanolysis of wheat straw (WS) and rice straw (RS) can be enhanced by Pretreatment using Trichoderma sp. AH, particularly the esters of the methanol-soluble portion (MSP) of WS and RS in supercritical methanolysis. However, only about 100 organic compounds of lower volatility and polarity could be detected in MSP by gas chromatography-mass spectrometry. Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry was used to determine the organic nitrogen compounds (ONCs) in the MSPs from supercritical methanolysis of raw and pretreated WS with Trichoderma sp. AH. The most prevalent ONCs in the MSPs of native and pretreated WSs in the positive ion mode would be N2On (n = 1–9) species having twin-bonding equivalence values (2–25) together with carbon-atom numbers of 4–35. Peak prevalent ONC within prior-treated WS MSPs is N2O4, with the most abundant ONC in raw WS MSPs is N2O5. These results help to understand the impact of Trichoderma sp. AH pretreatment upon converting ability/specificity for ONCs within WS methanolysis and employing MSP in producing jet fuel.

Flavonoids from Manilkara hexandra and antimicrobial and antioxidant activities

Manilkara hexandra (Roxb.) Dubard (family Sapotaceae) is an edible fruit-producing tree widely distributed in western and central Indian states and cultivated in Egypt. M. hexandra is well known for its various nutritional and medicinal merits. Structure elucidation of the isolated compounds using 1D and 2D NMR along with MS revealed the identification of two new flavonoids, myricetin 3-O (3″-O-methyl) α-L-rhamnopyranoside (1), and 3-O-ethyl-dihydroquercetin (3-O-ethyltaxifolin) (8) from M. hexandra leaves and fruits, respectively. Additionally, 4 known flavonoids were identified from the leaves as β-4′-methoxy-myricetin-3-O-α-L-rhamnoside (2), 4′-methoxy-quercetin-3-O-α-L-rhamnoside (3), quercetin-3-O-α-L-rhamnoside (5), and myricetin-3-O-α-L-rhamnoside (6), together with 4 known compounds from fruit identified as gallic acid (7), myricetin (9), taxifolin (10) and quercetin (11) in addition to methyl gallate (4). The isolated new compounds were investigated for their in vitro antimicrobial activity against 4 fungal and 8 bacterial strains. Compounds 1 and 8 showed antifungal activity against 3 fungal strains, and potent antibacterial activity was observed against tested gram positive and gram negative bacteria with the highest inhibition effect against Pseudomonas aeruginosa with MIC 3.9 μg/mL. The antioxidant activity of M. hexandra leaves and fruits aqueous methanol extract and methanol soluble portion was evaluated using DPPH method revealing DPPH radical scavenging activity and the fruit methanol soluble portion (FMSP) was the most active with SC50 = 12.8 (μg/mL) nearly equal to that of ascorbic acid.

Two-step separation for enriching phenols and esters from base-catalyzed depolymerization of sorghum stalk

Base-catalyzed depolymerization of sorghum stalk using Na2CO3, NaOH, and CaO was performed to afford methanol-soluble portion, and then extraction together with column chromatography was employed for enriching phenols and esters. The maximum total yield (ca. 53 wt%) of extract solutions 1–5 (ES1–ES5) was acquired at 280 °C with the equal mass of CaO and sorghum stalk. According to gas chromatograph/mass spectrometer analysis, phenols and esters are the predominate products. The phenols obtained from Na2CO3-catalyzed depolymerization of sorghum stalk mainly are methoxylphenols, while those obtained from NaOH and CaO-catalyzed depolymerization are dominated by alkylphenols, suggesting that NaOH or CaO plays an important role in demethoxylation during biomass depolymerization process. Phenols, methyl alkanoates/benzenecarboxylates, and dimethyl alkanedioates were roughly enriched into ES1, ES3, and ES5via sequential extraction with petroleum ether (PE), PE, and ethoxyethane, respectively. By the following column chromatographic separation of ES1 and ES3, alkylphenols and guaiacols were mainly enriched into PE/CS2 (4:3)-eluted fractions with maximum concentration of 92.2% and 92.1%, respectively. Saturated and unsaturated methyl alkanoates were isolated in concentration of near 100% by elution with PE/CS2 (9:1) and PE/CS2 (4:3), respectively. Extraction combined with column chromatography as two-step separation provides a promising approach for enriching phenols and esters from biomass-derived liquids.

Deep catalytic hydroconversion of straw-derived bio-oil to alkanes over mesoporous zeolite Y supported nickel nanoparticles

A supported nickle catalyst was prepared by loading ca. 11% of nickel nanoparticles (NNPs) on mesoporous zeolite Y (MZY) and denoted as Ni11%/MZY. A straw was methanolyzed at 300 °C to obtain methanol-soluble portion as a straw-derived bio-oil (SDBO) in the yield of 19.3%. According to the analysis with a gas chromatograph/mass spectrometer, SDBO consists of arenes (7.8%), oxygen-containing organic compounds (82.8%), nitrogen-containing organic compounds (6.3%), and sulfur-containing organic compounds (3.1%). It was subjected to catalytic hydroconversion (CHC) over Ni11%/MZY in n-hexane under 5 MPa of initial hydrogen pressure (IHP) at 160 °C for 16 h. As a result, all the compounds in SDBO were converted to chain alkanes (60.1%) and cyclanes (39.9%). In Ni11%/MZY, uniformly dispersed NNPs and strong Lewis acid sites in the defective crystal texture of MYZ play crucial roles in hydrogenating aromatic rings and removing heteroatoms (HAs), respectively. Benzyloxybenzene (BOB) was used as a lignin-related model compound. The main product from the CHC of BOB over Ni11%/MZY in n-hexane under 5 MPa of IHP at 160 °C for 2 h is methylcyclohexane in the yield of 90.9%, indicating that both hydrogenation of benzene rings and deoxygenation significantly proceeded. After being recycled 4 times, Ni11%/MZY is still active for the CHC of BOB.

Molecular Characterization of Lignite Extracts of Methanol and Carbon Disulfide/N-Methyl-2-pyrrolidone by High-Resolution Mass Spectrometry.

CS2/N-methyl-2-pyrrolidone (NMP) could extract much more substance from coals than any other solvents. Investigation on the molecular composition of CS2/NMP extracts from lignite is significant for the understanding of high extraction yield and the clean utilization of coal. The methanol-soluble portions from lignites and CS2/NMP extracts of lignites were characterized by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The yield of CS2/NMP extracts from lignite was quite higher than that of methanol extracts. Furthermore, the yield of methanol-soluble portions from CS2/NMP extracts was far more than that of methanol extracts from lignite. At the level of molecular composition, the relative content of heteroatom compounds with more oxygen atoms, longer side chain, and higher condensation in the CS2/NMP extract was also higher than that in the methanol extract. Despite great difference in the yield and the relative content of components, the distributions of species, molecular weight, carbon number, and double-bond equivalent were similar to those of most organic molecules for the methanol extract and methanol-soluble portions from the CS2/NMP extract. These phenomena suggested that organic molecules with similar structure but different composition, nonuniformly distributed in the coal matrix, were released more in the CS2/NMP extract compared to the single methanol extract.

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.

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. 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. 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. 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.

Chemical Studies and Antibacterial Activity of the Root of Rumex abyssinicus

One of the Ethiopian endemic plants used traditionally as medicine for different diseases is Rumex abyssinicus. It is widely known as ‘Meqmeqo’ in Amharic. The aim of this study was to isolate and characterize compounds from the root of R. abyssinicus and to test their bioactivities of solvent fractions of the extract. The crude extract was extracted from dried powdered root of the plant with methanol. Then it was fractionated with n‑hexane and ethyl acetate with increasing polarity. The yellow powder obtained from ethyl acetate fractionation was applied to column chromatographic separation that led to the isolation of two compounds, diisobutyl phthalate and emodine. Finally, antibacterial evaluation of the ethyl acetate and methanol soluble portions were carried out against four pathogenic bacteria. Both methanol and ethyl acetate soluble portions inhibited all selected bacterial in better at high concentrations.

Insight into structural features of soluble portions from cellulose, cellobiose and monosaccharide methanolysis by GC/MS and ESI FTICRMS

Methanolysis of biomass has attracted increasing attention due to it has some advantages, such as low critical points and strong hydrogen donation ability. In this paper, methanolysis of cellulose, cellobiose (sucrose), and monosaccharide (glucose) were performed to obtain methanol-soluble portions (MSPs). The relatively volatile or less polar species in the MSPs were analyzed with a gas chromatograph/mass spectrometer (GC/MS), and the polar species were identified with a negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS). According to analysis with GC/MS, the MSPs include ethers, esters, ketones, acids, sugars, phenols, and furans. The analysis with FTICRMS shows that the polar compounds in the MSPs are O1–O15 class species with 1–14 double bond equivalent (DBE) and 5–35 carbon atom number (CAN). The most abundant class species in MSPs from cellulose, sucrose, and glucose methanolysis are O5, O7, and O7, respectively. The species in MSPs from sucrose and glucose methanolysis center at higher DBE value and more CAN than those in MSP from cellulose methanolysis. Meanwhile, the oxygen atom number of O4–O10 class species in the MSPs were negatively correlated with the average DBE value. The results indicate that condensation intensively proceeded with the specific regularity during sucrose and glucose methanolysis.

Clean and effective catalytic hydrolysis of bagasse waste to small-molecular compounds over a hydrothermally stable Ru/La(OH)3

Ruthenium/lanthanum hydroxide (Ru/La(OH)3), a hydrothermally stable catalyst, was prepared and used for catalyzing hydrolysis of bagasse, a sugar industry waste, to small-molecular compounds under low initial H2 pressure (IHP 0.2 MPa, 5% H2 in 4 MPa H2 and N2 mixture) at 240 °C. Neither oligomers nor char was formed and bagasse was almost completely converted into soluble portion (SPCH, 59.1 wt%) and gaseous products by the catalytic hydrolysis (CH). Obviously different from the methanol-soluble portion and ethanol-soluble portion from the bagasse methanolysis and ethanolysis, in total 104 organic compounds were detected in SPCH, among which alkyl-substituted phenols & benzenepolyols (38.8%), alkoxy-substituted phenols (22.2%), ketones (15.1%), and carboxylic acids (12.2%) are dominant according to the analysis with a gas chromatograph/mass spectrometer (GC/MS). Based on the analysis with a quadrupole exactive orbitrap mass spectrometer, heteroatom-containing compounds, especially oxygenates, are predominant in the SPs, while more species including smaller molecular fragments, can be identified in SPCH, which is consistent with the analysis with GC/MS. In addition, the catalytic hydroconversion of phenethoxybenzene over Ru/La(OH)3 further confirms that appropriately raising the temperature and reducing the IHP facilitate the formation and transfer of active H∙. In one-pot, clean and effective conversion of bagasse with low H2 consumption and in a green solvent can be achieved through this strategy.

Pretreatment with Trichoderma sp. AH enhances conversion and specificity of wheat straw in supercritical methanolysis

Supercritical methanolysis (SCM) of pretreated wheat straw (WS) with the white-rot fungus Trichoderma sp. AH was investigated. Structural change of pretreated WS was examined by Fourier transform infrared spectrometric analysis and chemical analysis as well as observation with a scanning electron microscope. The optimal pretreatment (PT) time of WS was 5 days of incubation, obtaining the maximum methanol-soluble portion (MSP) yield of 38.3% at 260 °C, compared with MSP yield of 24.6% of raw WS. According to the detailed compositional analysis of MSPs from SCM of raw and pretreated WS, after 5 days of incubation, PT with Trichoderma sp. AH enhanced conversion, specificity and content of esters significantly. Especially, the relative contents of methyl palmitate, methyl (9Z,12Z)-octadeca-9,12-dienoate, and methyl (E)-octadec-11-enoate in MSPs were increased dramatically. Therefore, the study brings out the potential of PT with Trichoderma sp. AH for facilitating conversion and specificity of biomass in liquefaction.

Identification of organooxygen compounds in the methanol-soluble portion from the methanolysis of pretreated rice straw with Trichoderma sp. AH

The effect of pretreatment (PT) with Trichoderma sp. AH on the organooxygen compounds (OOCs) in methanol-soluble portions (MSPs) obtained from the methanolysis of raw and pretreated rice straw (RS) was investigated. According to the analyses with a gas chromatograph/mass spectrometer (GC/MS) and negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer, molecular masses (MMs) of the OOCs range from 100 to 500 u and are dominant from 300 to 450 u. The relative abundances of detected compounds with MMs from 300 to 350 u in MSP of pretreated RS are higher than those in MSP of raw RS. The predominant compounds in MSPs of raw and pretreated RSs are On (n = 1–10) with double bond equivalent (DBE) values of 1–28 and carbon atom numbers (CANs) of 4–35. The most abundant classes in MSPs of raw and pretreated RSs are O5 and O4, respectively. Besides, N1On (n = 0–9) classes with DBE values of 1–23 and CANs of 4–35 were also identified. These results facilitate understanding the effect of pretreatment with Trichoderma sp. AH on RS conversion and OOC selectivity from the methanolysis of RS and the application of MSP in producing transportation fuel.

Comparative studies on the structural features of soluble portions from thermal dissolution/methanolysis and catalytic hydroconversion of an extraction residue from Heishan lignite

Heishan lignite (HL) was extracted with isometric acetone/carbon disulfide mixed solvent under ultrasonic irradiation. The extraction residue (ER) was subjected to thermal dissolution/methanolysis (TD/M) in methanol and catalytic hydroconversion (CHC) in cyclohexane (CH) at 300 °C under 1 MPa of N2 over a supported acid (SA). The methanol-soluble portion (MSP) from the TD/M and CH-soluble portion (CHSP) from the CHC were analyzed with a gas chromatograph/mass spectrometer (GC/MS) and Fourier transform infrared (FTIR) spectrometer, while ER and the residues from the TD/M (RTD/M) and CHC (RCHC) were characterized with the FTIR spectrometer and an X-ray photoelectron spectrometer (XRPES). The results show that the yields of MSP and CHSP are ca. 22.6% and 16.1%, respectively. According to the analysis with GC/MS, CHSP is rich in tetramethylbenzenes and dimethylnaphthalenes, while most of the GC/MS-detectable compounds in MSP are xylenols, trimethylphenols, and methyl normal alkanoates. During the TD/M, the cleavage of some CO bonds could be the main reaction, whereas the SA effectively catalyzed the cleavage of CarCalk bonds connecting some aromatic rings (ARs) and side chains on the ARs in ER. No significant difference in the distribution of functional groups was observed in FTIR spectra between HL and ER, while the distribution of functional groups in MSP is extraordinarily different from that in CHSP. According to the analysis with XRPES, RTD/M has higher carbon content but lower oxygen content.

Effects of thermal dissolution in different solvents on structural characteristics and pyrolysis behaviors of lignite

Thermal dissolution (TD) of Xilinhaote lignite (XL) in n-hexane, toluene and methanol were carried out, and then the residues of thermal dissolution (RTDs) and XL were pyrolyzed at a low temperature of 550 °C to explore the effect of TD on structural characteristics and pyrolysis behaviors of XL. Results show that RTDs present higher aromatic carbon content (fa), lower aliphatic carbon (fal) and oxygen-linked carbon content (fO), indicating that the molecular structure of XL becomes more ordered after TD, especially that in n-hexane. Among three RTDs, the RTD in methanol obtained at 290 °C (RTDM,290) exhibits the largest aromatic cluster size. The influences of TD at 290 °C on the pyrolysis behaviors of XL are remarkable. Compared with XL , the pyrolysis of RTDs obtained at 290 °C (RTD290s) present higher char yields, lower tar, gas and water yields. The pyrolysis of RTD in n-hexane obtained at 290 °C (RTDH,290) exhibits extremely low tar yield, suggesting that the low molecular weight compounds (LMWCs) isolated from XL during TD can transport into tar and/or act as hydrogen donors to stabilize the radical fragments during pyrolysis processes. Although the methanol soluble portion (SP) yield is up to 9.45% at 290 °C, the tar yield of RTDM,290 is almost equal to that of XL, indicating that the swelling effect of XL in methanol is significant and it is conducive to the production of tar.

Sequential thermal dissolution and alkanolyses of extraction residue from Xinghe lignite

Extraction residue (ER) from ultrasonic extraction of Xinghe lignite (XL) was subjected to sequential thermal dissolution (TD) in cyclohexane from 200°C to 320°C and subsequently in benzene, methanol, ethanol, and isopropanol at 320°C. The yields of soluble portions (SPs) in methanol and ethanol are much higher than those in cyclohexane and benzene, and the total SP yield is ca. 48.3%. According to gas chromatography/mass spectrometric analysis, the most abundant group components are arenols in cyclohexane-soluble portion obtained at 290°C and methanol-soluble portion obtained at 320°C, arenes in both cyclohexane- and benzene-soluble portions obtained at 320°C, alkanoates in ethanol-soluble portion obtained at 320°C, and alkenones in isopropanol-soluble portion obtained at 320°C. Anthracene was used as hydrogen acceptor to probe hydrogen transfer (HT) from ER in terms of the formation of 9,10-dihydroanthracene (DHA) and 1,2,3,4-tetrahydroanthracene (THA) during TD. As a result, both DHA and THA were detected in all the SPs except benzene-soluble portion obtained at 320°C and the yields of both DHA and THA increased with raising temperature in cyclohexane, indicating that raising temperature enhances HT from ER to anthracene. Compared to TD in cyclohexane, alkanols, especially isopropanol, enhance the HT more significantly at 320°C.

Improvement of organonitrogen compounds in methanol-soluble portion from supercritical methanolysis of pretreated rice straw with Trichoderma sp. AH

The improvement of organonitrogen compounds (ONCs) in methanol-soluble portions (MSPs) obtained from supercritical methanolysis of raw and pretreated rice straw (RS) with Trichoderma sp. AH was investigated. According to detailed analysis with positive-ion ESI FT-ICR MS and GC/MS, the molecular masses (MMs) of ONCs in MSPs of raw and pretreated RS range from 100 to 500u and dominate from 300 to 450u. The relative abundance of ONCs with MMs from 300 to 350 u in MSP of pretreated RS is higher than those in MSP of raw RS. Most of detected ONCs in MSPs of raw and pretreated RS are N2On (n=1–9) species with double bond equivalent values of 2–25 and carbon atom numbers of 4–35. The most abundant ONCs in MSP of pretreated RS are N2O4, while those in MSP of raw RS are N2O5. These results facilitate understanding the effect of pretreatment with Trichoderma sp. AH on the conversion and specificity of ONCs in methanolysis of RS and the application of MSP on production of transportation fuel.

Supercritical methanolysis of rice straw pretreated with Trichoderma sp. AH

Supercritical methanolysis (SCM) of pretreated rice straw (RS) with the white-rot fungus Trichoderma sp. AH was investigated. Structural change of the pretreated RS was examined by Fourier transform infrared spectrometric analysis and chemical analysis as well as observation with a scanning electron microscope. The optimal pretreatment time is 10days, obtaining the maximum methanol-soluble portion (MSP) yield of 28.2% at 260°C, compared with the MSP yield of 20.9% from SCM of the unpretreated RS. Under such conditions, the yields of esters, especially methyl 12-methyltetradecanoate, methyl palmitate, methyl 3,7,11,15-tetramethylpalmitate, methyl (9Z,12Z)-octadeca-9,12-dienoate, and methyl (E)-octadec-13-enoate, significantly increase.

Identification of organic nitrogen compounds in methanol-soluble portion from sweet sorghum stalk methanolysis

Understanding the chemical composition of organic nitrogen compounds (ONCs) in biomass and its derived liquids is important because of their negative impacts on the environment during biomass utilization as fuel. In this study, X-ray photoelectron spectrometer (XPS) was used to identify the nitrogen forms on sweet sorghum stalk (SSS) surface and gas chromatograph/mass spectrometer (GC/MS) together with electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS) were employed to analyze ONCs in methanol-soluble portion (MSP) from SSS methanolysis. Analysis with XPS shows that the nitrogen forms on SSS surface mainly include pyrrolic, amino, and quaternary nitrogen species. GC/MS identified 14 ONCs in MSP, including 3 pyrroles, 3 indoles, 2 imidazoles, 3-methoxypyridine, 1-(hex-5-enyl)-1-methylhydrazine, cyclohexanecarbohydrazide, N-pyridin-3-ylacetamide, 1,3,4-trimethyl-1H-pyrazol-5(4H)-one, and pyridin-3-amine. According to analysis with negative-ion ESI FTICRMS, N1On class species are the main neutral nitrogen compounds (NNCs) in MSP. N1O3 class species are the most abundant NNCs, followed by N1O4 and N1O5 class species. Pyrroles and indoles should be dominant NNCs based on double bond equivalent (DBE) distributions. In positive-ion mode, most of the detected basic nitrogen compounds in MSP are N2On class species, in which N2O2–N2O4 class species with DBE=8–12 and carbon atom numbers of 19–28 are the most abundant. N2On class species with DBE<4 are likely to be diamines, hydrazines, hydrazides, imidazoles, and/or pyrazoles, while those with DBE≥4 could be ascribed to pyridinamine, pyrazines, pyrimidines, benzoimidazoles, indazoles, and/or isoquinolinamines.

Characterization of soluble portions from thermal dissolution of Zhaotong lignite in cyclohexane and methanol

Thermal dissolution of Zhaotong lignite in cyclohexane and methanol was conducted at 300°C for 2h. The yields of the resulting cyclohexane- and methanol-soluble portions (CHSP and MSP) are 10.1% and 24.3%, respectively. CHSP and MSP were analyzed with a gas chromatograph/mass spectrometer (GC/MS) and negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS). According to analysis with GC/MS, the compounds detected in CHSP and MSP can be classified into alkanes, alkenes, arenes, arenols, anisols, ketones, esters, nitrogen-containing compounds, and sulfur-containing compounds. The most abundant group components in CHSP and MSP are arenols and arenes, respectively. The analysis with FTICRMS shows that On (n=1–6) class species with double bond equivalent (DBE) values of 1–15 are the main acidic compounds in both CHSP and MSP, and the predominant class species in CHSP and MSP are O2 and O3 class species, respectively. Arenepolyols and aromatic carboxylic acids with 1–3 rings account for most of the On class species based on DBE distributions. In addition, fatty acids are also present in CHSP and MSP. Combination of GC/MS and FTICRMS can provide detailed composition information on coal-derived liquids at the molecular level.

Catalytic hydroconversion of methanol-soluble portion from Xiaolongtan lignite over difunctional Ni/Z5A

A highly active difunctional supported nickel catalyst Ni/Z5A was prepared by thermally decomposing nickel carbonyl onto zeolite 5A (Z5A). The catalytic hydroconversion (CHC) of methanol-soluble portion (MSP) from the methanolysis of Xiaolongtan lignite was investigated over Ni/Z5A at 200°C. Detailed molecular compositions of MSP and catalytically hydrogenated MSP (CHMSP) were characterized with a Fourier transform infrared spectrometer, gas chromatograph/mass spectrometer (GC/MS), and negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer (ESIFTICRMS). According to analysis with GC/MS, MSP is rich in aromatic ring- and/or heteroatom-containing compounds, while most of the GC/MS-detectable compounds in CHMSP are chain alkanes and cyclanes. The analysis with ESIFTICRMS shows that both the number and yields of oxygen- and/or nitrogen-containing species in MSP were dramatically reduced after the CHC. These facts indicate that Ni/Z5A effectively catalyzed heteroatom (especially O atom) removal from MSP and hydrogenation of MSP. Naphth-1-ol and oxybis(methylene)dibenzene (OBMDB) were used as lignite-related model compounds and their CHCs were investigated to further understand the catalysis of Ni/Z5A in the CHC of MSP. As a result, Ni/Z5A proved to have 2 functions, i.e., activating H2 to biatomic active hydrogen (BAAH) and heterolytically splitting H2 to H+ relatively free from Ni/Z5A and H− adsorbed on Ni/Z5A. Over Ni/Z5A, the CHCs of naphth-1-ol and OBMDB proceeded via BAAH and H+ transfer to mainly produce tetralin and decalin from naphth-1-ol and methylcyclohexane and toluene from OBMDB.

Sweet sorghum stalk liquefaction in supercritical methanol: Effects of operating conditions on product yields and molecular composition of soluble fraction

Liquefaction of sweet sorghum stalk (SSS) in supercritical methanol was carried out under different conditions, including temperature, holding time, and SSS-to-methanol ratio. Each reaction mixture was filtrated to afford residue and bio-oil (BO, i.e., methanol-soluble portion). The optimal conditions were determined to be 300°C and 30min based on the BO yield and the maximum yield of BO is 40.5wt% with higher heating value of 25.1kJ g−1. Low SSS-to-methanol ratio, i.e., either more methanol volume or less SSS dose, benefits the BO yield. According to gas chromatograph/mass spectrometric analysis, the compounds detected in the BOs can be grouped into hydrocarbons, alcohols, phenolic compounds (PCs), methoxybenzenes, ketones, esters, and others. Among them, PCs and esters are the most abundant. Guaiacols and alkylphenols are predominant PCs, which were mainly originated from the decomposition of lignin in SSS. Esters can be further classified into long-chain methyl esters (LCMEs), short-chain methyl esters (SCMEs), dimethyl diesters, and polymethyl benzenepolycarboxylates. The variation of esters mainly relied on LCME and SCME change with varied reaction conditions.