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• The low loading of Ni/C catalysts are used for the HDO of guaiacol and bio-oil. • The guaiacol is completely converted to cyclohexanol over 5%Ni/C at 200 °C and 2 h. • The phenols derived from bio-oil are gradually converted to alcohols and cycloalkanes. • The C-O bond between benzene ring and methoxy group in guaiacol is first cleaved. It is significant to improve the quality of bio-oil to produce cyclohexanol and cycloalkane products through hydrodeoxygenation (HDO). Excellent and inexpensive catalysts facilitate the upgrading of bio-oils and phenols under mild conditions and subsequent industrial applications. Catalysts synthesized in previous studies have a high metal loading, resulting in increased production costs. Herein, a series of low loading of Ni/C catalysts (1–7%) were synthesized and applied for the HDO of lignin bio-oil and derived phenols. The characterization results demonstrated that 5%Ni/C possessed the smallest metal particle size and sufficient amount of Ni0, achieving a well conversion of phenols in bio-oil. A low loading of 5%Ni/C can produce enough reactive H species in a short time. Therefore, guaiacol was completely converted to cyclohexanol over 5%Ni/C at 200 °C and 2 h. The products of bio-oil conversion were gradually hydro-deoxidized to cyclohexanol compounds and cycloalkanes over 5%Ni/C. The deuterium experiment revealed that the major pathway for the transformation of guaiacol was to first break the C-O bond between the benzene ring and methoxy group. Besides, other bio-oil derived phenols (phenol, cresol and vanillin, etc.) were fully transformed to related cyclohexanols over 5%Ni/C. This study provides a prospective catalyst for the HDO of lignin bio-oil and derived phenols. [ABSTRACT FROM AUTHOR]

To investigate the molecular composition of soluble organic species in Baiyinhua lignite (BL) and their evolution profiles during pyrolysis, BL was firstly pyrolyzed in a fixed-bed reactor, affording gaseous products, tars and chars, then BL and its chars were thermally dissolved in supercritical methanol affording soluble portions (SPs). The composition and structural characteristics of the SPs and tars were analyzed with a gas chromatograph/mass spectrometer. The results indicate that most of the soluble organic species can be released from BL below 500 °C during pyrolysis. Abundant soluble long-chain aliphatic hydrocarbons and carboxylic acids wrap around the aromatic nucleus in BL. According to the difference between the composition and structural characteristics of the SPs and tars, the evolution profiles of the soluble organic species from BL pyrolysis were discussed in detail. [ABSTRACT FROM AUTHOR]

In this paper, two typical Chinese lignites, Shengli lignite (SL) and Xiaolongtan lignite (XL), with different geologic ages were firstly thermal dissolved in sub- and supercritical benzene and ethanol, then soluble organic species were analyzed with Fourier transform infrared spectroscopy (FTIR), gas chromatograph/mass spectrometer (GC/MS) and atmospheric solids analysis probe/time of flight mass spectrometer (ASAP/TOF-MS). The soluble organic species yield of XL in benzene is close to that of SL in the temperature investigated, whereas the soluble organic species yield of XL in ethanol is obviously higher than that of SL at high temperature region. Obvious difference exists in the molecular composition of the soluble organic species between SL and XL. The soluble organic species of XL contain more free aliphatics but less arenes than those of SL. The arenes in the soluble organic species of XL are mainly composed of the derivatives of benzene and naphthalene, while those from SL are dominated with condensed arenes and polycyclic biphenyls. Furthermore, the free oxygen-containing organic species in SL and XL are dominated with ketones and phenols, respectively. Additionally, ASAP/TOF-MS analysis indicates that the molecular weight of soluble organic species from SL is higher than that from XL. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe/NC catalyst shows good activity and stability for cleaving C-O bonds in lignite. • Fe-N and Fe/Fe 3 C species in the catalyst were crucial to the catalytic activity. • Active hydrogen species were hydrogen radicals generated from H 2 and isopropanol. • The hydrocracking products have higher H/C ratio and heating values than lignite. • Catalytic hydrocracking promoted producing phenols via the cleavage of C-O bonds. Cleaving C-O bridged bonds of lignite via catalytic hydrocracking (CHC) is an effective method to produce chemicals and clean fuels. Herein, a nitrogen-doped carbon supported Fe catalyst was developed by using a one-pot method for CHC of Xilinguole lignite (XL) and its related model compounds. The doped nitrogen enhanced the interaction between Fe and N species to form Fe-N sites and favored forming smaller Fe/Fe 3 C nanocrystals, which played a crucial role in CHC performance. Toluene and phenol were produced from CHC of benzyl phenyl ether (BPE) with high yield and selectivity at 250 °C over the optimal catalyst with 4% Fe, without hydrogenation products. The Fe-based catalyst activated both H 2 and isopropanol to generate hydrogen radicals for cleaving C-O bridged bonds. The CHC of XL under different temperature and time showed that the yields of oil, asphaltene and preasphaltene were obviously promoted under 325 °C, 1 MPa, and 6 h, and they had much higher H/C ratio but remarkably lower O/C ratio, resulting in much higher heating values (28.19–36.90 MJ/kg) than XL. Phenols were the major group component with relative content of 53.6 wt% in oil from CHC, and the asphaltene and preasphaltene from CHC had obviously lower molecular weights, which could attributed to depolymerization of C-O bridged bonds in the XL macromolecular structures over the catalyst. [ABSTRACT FROM AUTHOR]

• A particulate loading and active regeneration cycle of the diesel particulate filter were performed on a burner. • Most ash-bridges were observed in the middle region of the diesel particulate filter channel. • Using Ca-based or Mg-based additive lubricants is beneficial to reduce the ash-bridge deposition. • When the blockage rate is greater than about 70%, the channels near the ash bridge are destroyed. Diesel particulate filter (DPF), an important after-treatment system, is widely used to trap particulates from diesel engines. After many active regenerations of the DPF, non-volatile ash may form an ash bridge phenomenon in the DPF channel. This paper studies the effects of lubricant components on ash-bridge deposition characteristics in the DPF. Four test lubricants were prepared based on the CK-4 standard lubricant with four different additives (Ca-based, Mg-based, compound, and Zinc dialkyl dithiophosphate (ZDDP) additives), which were separately and proportionately blended into diesel fuel to form four different fuels. A particulate loading and active regeneration cycle of the DPF with those fuels were performed on a burner. The results show that mid-channel ash deposits (MCD) and the ash-bridge phenomenon were observed in the DPF with all four fuels, and the ash-bridge was mainly located in the middle region of the DPF channel. Mg-based or ZDDP additives can improve the ash-channel ratio (A: C) of the MCD. Ca- or Mg-based additives can reduce the distribution density of ash bridges and avoid sintering of DPF. Different shapes of ash bridges will cause different blockage rates in the DPF channel. When the blockage rate of the DPF channel is greater than about 70 %, DPF channels near the ash bridge are destroyed. [ABSTRACT FROM AUTHOR]

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]

Thermal dissolution (TD) plays an important role in obtaining soluble components from low-rank coals. Characterization of the TD product is essential for both optimization of TD conditions and in-depth understanding of molecular structures in coal that is crucial for the refining processes. In-source collision-activated dissociation (ISCAD) combined with high-resolution mass spectrometry (MS) was employed in this study to analyze four TD products of a low-rank coal obtained by using cyclohexane, acetone, methanol and ethanol as solvents. ISCAD-MS allows the evaluation of distributions of oxygen and nitrogen atoms located within aromatic cores or on alkyl chains based on the abundances of heteroatom-containing precursor ions and fragment ions. In addition, ISCAD-MS can evaluate the abundance of multi-core compounds based on the change of average double bond equivalent value upon fragmentation. These structural details advance the current understanding of the TD products at the molecular level. [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]

HZSM-5 was modified via alkaline treatment and wet impregnation method which loading transition metals (Co, Mo–Co and Ni–Co). The performance of catalysts for the catalytic fast pyrolysis of lignite was tested in a drop tube reactor at 600 °C. In comparison to non-catalytic experiment, the chemical composition of upgrading tar was obviously simplified, which mainly contains light aromatics such as benzene, toluene, ethylbenzene, xylene and naphthalene (BTEXN). The yield of BTEXN was significantly increased from 12.9 to 26.4 mg/g when Ni/Co-H-5 was used. Meanwhile, the Ni/Co-H-5 treated by NaOH solution achieved considerable deoxygenation performance (86.6%) than other ones. The addition of bimetallic Mo–Co or Ni–Co significantly enhanced the BTEXN selectivity of HZSM-5. Ni promoted H 2 formation in gaseous product and caused the decrease of naphthalenes yield. Whereas the yields of toluene and o -xylene increased after the pyrolysis vapors pass through Mo/Co-H-5. The zeolite treated by NaOH solution (AT-HZSM-5) favors the generation of aromatics and phenolics, conversely naphthalene derivatives. Moreover, AT-Mo/Co-H-5 and AT-Ni/Co-H-5 inhibited the coke formation. A catalytic pathway was also proposed to describe the diffusion process of pyrolysis vapors on the active site of catalyst. [ABSTRACT FROM AUTHOR]

Detailed characterization of organic components in low-rank coals is essential for the utilization of coals in clean, effective and value-added ways. Two kinds of low-rank coals were subjected to sequential thermal dissolution in the order of cyclohexane, acetone, and methanol to obtain six soluble portions (SPs) from the coals. Two gas chromatographic systems, gas chromatography/mass spectrometry (GC/MS) and comprehensive two dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC/TOF MS), were applied to the characterization of the SPs. Compared to GC/MS, a routine analytical technique for complex mixtures, GC × GC/TOF MS improves the separating power, overcomes the co-elution, and reveals more structural details in complex mixtures like coals. Low-polar compounds like aliphatic hydrocarbons and arenes tended to be extracted by cyclohexane. High content of polar alcohols and phenols were identified in the SPs of methanol. Acetone could enrich nitrogen-containing organic compounds (NCOCs) due to hydrogen bond of N–H⋯O between NCOCs and acetone. Additionally, a series of low-concentration species including some isomers in the SPs were only identified by GC × GC/TOF MS. Distributions of various classes of compounds on the two-dimensional total ion chromatograms plot were discussed according to the separation mechanism of the two columns. Detailed analysis of biomarkers was also exhibited and discussed. [ABSTRACT FROM AUTHOR]

Lignite is rich in oxygen-containing species (OCSs) and able to load Ni via ion exchange to prepare Ni/C catalyst. However, the OCSs usually exists in the form of organic salts, which can reduce the capacity of Ni ion exchange. In this paper, Shengli lignite (SL) was treated with HCl and HCl/HF to selectively remove the organic salts and insoluble minerals, respectively, and the modified lignite was oxidized by H 2 O 2 to further increase the carboxyl content. The treated lignite was used to prepare Ni/C catalyst and the activity for biomass volatile reforming was evaluated. The results show that demineralization (DM) caused the corrosion of pore structure of SL and gave a Ni/C catalyst with a low specific surface area (SSA) of 222.1 m 2 /g. Oxidation with H 2 O 2 further destroyed the structure of DMSL and provided a Ni/C with the lowest SSA of 141.1 m 2 /g. Acid wash (AW) with HCl resulted in the increase of ion exchange capacity of SL and gave a Ni/C catalyst with larger SSA, higher loading, lower particle size and well dispersion of Ni particle in comparison with SL and DMSL. H 2 O 2 treatment of AWSL significantly increased the amount of carboxyl group to 3.8 mmol/g and gave a Ni/C with the largest SSA of 291.1 m 2 /g, highest Ni loading of 17.3% and smallest Ni crystallite size of 3.4 nm, as well as most active for corncob volatile reforming. [ABSTRACT FROM AUTHOR]

[Display omitted] • Highly active Ni/Al 2 O 3 catalysts were synthesized from LDHs precursors. • Ni/Al 2 O 3 -500 exhibited excellent catalytic performance in the hydrogenolysis of DPE. • Various lignin model compounds can be completely converted to monomeric products. • Ni/Al 2 O 3 -500 possesses excellent stability and recyclability. Catalytic hydrogenolysis of C O bonds in lignin provides a promising route to produce high value-added biofuels and chemicals. However, designing highly active and stable catalysts for this process is still a challenge. Herein, a series of Ni/Al 2 O 3 catalysts were synthesized by calcination and reduction of layered double hydroxide precursors, and their activities were evaluated in the catalytic conversion of lignin-derived compounds. Diphenyl ether was completely converted with a 100% monomeric selectivity (cyclohexane and cyclohexanol) over the optimized Ni/Al 2 O 3 -500 under the optimal conditions of 200 ℃, 0.5 MPa H 2 and 1.5 h, indicating the excellent catalytic activity in the cleavage of C O bonds of the catalyst. The excellent catalytic performances of Ni/Al 2 O 3 -500 were originated from its relatively large specific surface area, well-developed porosity, small crystallite size, high Ni0 concentration and strong interaction between the active metal and support. The reusability experiments show that Ni/Al 2 O 3 -500 possesses a relatively high stability for six reuses. Moreover, various lignin model compounds can be completely converted to corresponding monomeric products over Ni/Al 2 O 3 -500, indicating the applicability of this ingenious catalyst. The application of the hydrotalcite-derived Ni-based catalysts with high activity and stability provides a promising approach for the efficient hydrogenolysis of lignin derivatives. [ABSTRACT FROM AUTHOR]

Shengli lignite (SL) was oxidized and depolymerized in aqueous sodium hypochlorite under mild conditions followed by sequential extraction with ethoxyethane and ethyl acetate. The extracts were analyzed by Fourier transform infrared spectroscopy, gas chromatograph/mass spectrometry (GC/MS), time-of-flight mass spectrometry (TOF-MS) equipped with electrospray ionization (ESI), and direct analysis in real time (DART) to understand the structural features of SL. In total, 130, 272, and 818 compounds were identified by GC/MS, ESI-MS, and DART-MS, respectively, and the corresponding molecular mass distributions are between 70 and 322, 114 and 664, 113 and 753 u , respectively. GC/MS detected molecules with low molecular mass and polarity, and the major species include aliphatic acids, benzene polycarboxylic acids, chloro-substituted species and nitrogen-containing compounds. A large number of heteroatom-containing compounds (oxygen, nitrogen and sulfur) with relatively high molecular mass and unsaturation degree were determined using ESI-MS. As an ambient ionization technique, DART speeded up the analysis time with little or no sample pretreatment. Compared to the other two MS techniques, DART-MS broadened the measurement range, and O x N 5 , and O x N 6 classes were only detected by DART-MS. [ABSTRACT FROM AUTHOR]

Thermochemical conversion of crops straw is receiving renewed attention, due to the energy and material recovery that can be achieved. However, it still lacks the kinetic background which is of great importance for a successful design of thermochemical process. In this work, pyrolysis test for soybean straw was performed in a non-isothermal thermogravimetric analysis (TGA) in order to determine the thermal degradation behavior. Pyrolysis experiments were carried out under inert conditions and operated at different heating rates (5, 10, 20, and 30 K/min). Three different kinetic models, iso-conversional Kissinger–Akahira–Sunose (KAS), Ozawa–Flynn–Wall (OFW) models, and Coats–Redfern method were applied on TGA data of soybean straw to calculate the kinetic parameters including activation energy, pre-exponential factor, and reaction order. The activation energy values were 154.15 and 156.22 kJ/mol based on KAS and OFW models, respectively. Simulation of the soybean straw thermal decomposition using the obtained kinetic parameters and comparison with experimental data are in good agreement. [ABSTRACT FROM AUTHOR]

A Xinjiang subbituminous coal was directly oxidized in aqueous sodium hypochlorite and sequentially extracted with diethyl ether and ethyl acetate. The extracts were esterified with diazomethane and the esterified products were analyzed using a high performance liquid chromatograph/mass spectrometer (HPLC/MS) equipped with atmospheric pressure photoionization (APPI) or electrospray ionization (ESI) ion source. Toluene and a toluene/anisole mixture (vol/vol = 95:5) were used as dopant for APPI-MS. The relative of organic species with molecular mass over 500 u detected by ESI-MS is much higher than that identified by APPI-MS with and without dopant. The addition of dopant greatly enhanced the ionization efficiency and toluene induced better ionization effects compared to the mixture in both ion signal intensity and number of detected species. However, according to the ionization mechanism of APPI, a small portion of analytes could be well ionized under direct APPI mode rather than dopant-assisted mode. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Ni@Fe/NC shows good activity and selectivity for cleaving C-O bond in lignin. • NiFe alloy is formed in the catalyst which plays a crucial role in hydrogenolysis. • Aromatics especially guaiacols are dominant products from hydrogenolysis of lignin. • Possible reaction pathways based on hydrogenolysis of BPE and lignin were proposed. The utilization of lignin to produce high value-added chemicals is conducive to alleviating the fossil energy crisis. Herein, Ni nanoparticles supported on iron/nitrogen co-doped carbon was prepared by co-pyrolysis and solvothermal reduction method for catalytic hydrogenolysis (CH) of dealkaline lignin and its model compounds. The catalysts were prepared under different calcination temperature, N/C ratio and Ni loading, and the optimal catalyst was Ni 10% @Fe/NC 0.33 – 800 (calcination temperature: 800 °C, N/C ratio: 0.33, Ni loading: 10%) based the on the CH of benzyl phenyl ether (BPE). Ni 10% @Fe/NC 0.33 – 800 showed good catalytic performance on the selective cleavage of C-O bond of lignin and its model compounds. The BPE conversion reached up to 97.7% over Ni 10% @Fe/NC 0.33 – 800 under mild conditions (230 °C, 1 MPa H 2 , and 0.5 h) with toluene and cyclohexanol as major products. Catalyst characterizations suggest that N content affects the formation of NiFe alloy and the synergistic effect between Ni and Fe plays an important role in CH of BPE. Moreover, Ni 10% @Fe/NC 0.33 – 800 could promote the cleavage of C-O bonds in dealkaline lignin through CH and hence enhance producing aromatics such as phenols, aromatic ethers, and aromatic esters, among which phenols are the main aromatics with guaiacols predominant. [ABSTRACT FROM AUTHOR]

Highlights: [•] LRMC alkanolysis includes nucleophilic attack, hydrogen transfer and bond cleavage. [•] Reactivities of the LRMCs toward alkanolysis are: BOB>anisole>PEB>ODB. [•] For the same LRMC, ethanolysis proceeds much easier than methanolysis. [Copyright &y& Elsevier]

Highlights: [•] ASAP was applied to analyze CRMCs, exploring a new application field. [•] The ionization mechanism of produced M+ and [M+H]+ for CRMCs were investigated. [•] The ASAP/MS fragmentation pathways for selected CRMCs were proposed. [Copyright &y& Elsevier]

Highlights: [•] SL was pretreated with H2O2 and then oxidized in NaOCl aqueous solution. [•] The pretreatment significantly increased the yields of soluble species. [•] The pretreatment enhanced the formation of compounds with m/z 300 to 500. [•] The formation of chloro-substituted alkanoic acids was inhibited by the pretreatment. [•] Increase in yields of soluble species is ascribed to introduction of −COOH and −OH. [Copyright &y& Elsevier]

Abstract: Structural features of Shengli lignite (SL) were investigated through ruthenium ion-catalyzed oxidation and oxidations in aqueous hydrogen peroxide (AHPO) and sodium hypochlorite (ASHC) under mild conditions. The results suggest that SL is rich in condensed aromatic species and hydroxyl-, methoxy-, and/or methyl-substituted benzene rings, and –CH2CH2– is a dominant bridged linkage connecting aromatic rings in SL. Aliphatic linkages connecting three aromatic rings also exist in SL. Most of the organic matter in SL was converted into soluble fractions in either AHPO or ASHC. The products from SL oxidation in AHPO are rich in hydroxyl- and/or methoxyl-substituted benzoic acids, alkanoic acids (AAs), and long-chain alkanedioic acids (ADAs), whereas those from SL oxidation in ASHC are mainly composed of benzene carboxylic acids, chloro-substituted short-chain AAs and ADAs. The nitrogen- or sulfur-containing species produced from SL oxidation provide important information on structural features of organic nitrogen and sulfur species in SL. [Copyright &y& Elsevier]

Abstract: Wheat straw (WS) was oxidized in a sodium hypochlorite (NaOCl) aqueous solution at 40°C followed by sequential extraction of the water-soluble fraction (WSF) with petroleum ether, carbon disulfide (CDS), diethyl ether and ethyl acetate (EA). The EA-inextractable solution was acidized and filtrated. The filtration was also sequentially extracted with the same series of solvents. In total, 38 organonitrogen compounds (ONCs) were identified by GC/MS analysis from the extracts. The ONCs can be classified into amides, sulfonamides, amines, an amino acid, nitriles, an isocyanatoethane, chloro(nitro)methanes, an oxime, N-heterocyclic compounds (NHCCs, most of them are pyrrolidones) and a benzohydrazide, indicating the diversity of ONCs in WS. NHCCs, amides and nitriles are the most abundant among the ONCs, implying that these types of species might be main existing forms of nitrogen in the oxidized WS and even in WS itself to some extent. Most of the ONCs, especially amides and pyrrolidones, were enriched in the CDS-extractable fraction from the WSF because of the strong π–π interaction between C S bond in CDS and C O bonds in the ONCs. This investigation provides an effective approach for understanding the modes of ONC occurrences in WS. [Copyright &y& Elsevier]

[Display omitted] • Selective hydrogenolysis of diphenyl ether C-O bond occurred over Ni/Nb 2 O 5. • The common hydrogen supply existed between H 2 and isopropanol. • Hydrodeoxygenation reaction hardly occurred due to the weak acidity of Ni/Nb 2 O 5. • The reaction route of the hydrogenolysis in DPE was presented. Selective cleavage of stable ether C-O bonds is particularly of significance for the valorization of lignin and designing high active and cheap catalysts attracts researchers to conduct a lot of investigations. The niobium species containing both Brønsted and Lewis acid sites can be applied in hydrodeoxygenation of diphenyl ether (DPE). It is important to regulate the acidity of niobium to achieve the selective cleavage of DPE without hydrodeoxygenation. Herein, the weakly acidic Ni/Nb 2 O 5 prepared by an incipient wetness impregnation method could efficiently cleave C-O bonds of DPE without hydrodeoxygenation. DPE was completely converted and the yields of target products (cyclohexane and cyclohexanol) reached 90% under the coexistence of H 2 and isopropanol. It was ascribed to the common hydrogen supply between H 2 and isopropanol which could produce more active hydrogen. Acetone was detected in the solution after the reaction, demonstrating that a dehydrogenation reaction of isopropanol provided hydrogen. In addition, the turnover frequency (TOF) and the apparent activation energy (E a) for catalytic hydrogenolysis of DPE revealed that Ni/Nb 2 O 5 possessed higher activity than Co/Nb 2 O 5 under the same conditions. The possible reaction pathways were also summarized and analyzed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthetic hollow ZSM-5 (HSZ5) possess higher selectivity for toluene and m/p-xylene. • None-modifier catalysts keep high stability after 7 cycle reactions. • 11HSZ5 exhibits hierarchical meso -microporesity to rich BTEXN at 600 °C. • xHSZ5 show low coke resistance during lignite pyrolysis. Light aromatics could be produced by catalytic fast pyrolysis (CFP) of lignite over HZSM-5 with shape selectivity and accessible active sites. However, the catalytic reactivity in the center crystal has not been fully exploited. In this work, the different hollow hierarchical porosity-tunable ZSM-5 were synthesized using polyethylene glycol as a soft template by a steam-assisted crystallization process. Compared with commercial HZSM-5, the synthesized HZSM-5 exhibited higher selectivity for alkylbenzene (toluene and m/p-xylene) with the yield of 9.91 mg/g (7.31 mg/g over commercial HZSM-5). The hollow HZSM-5 with pore-size fine-tuning were favorable to control the tiny different intermediates for shape-selective of benzene and alkylbenzene in CFP. In addition, the unmodified synthetic hollow catalysts also kept highly stability after seven cycle experiments due to the enhancement of molecules diffusion in crystal center, especially the alkylbenzene yield was sustained at approximately 7.38 mg/g during cycle experiments. The work provides a great prospect to promote the formation of alkyl aromatics in CFP. [ABSTRACT FROM AUTHOR]

• Ru/AC exhibited high activity and selectivity for cleaving of C-O bond in BPE. • The turnover frequency and activation energies of Ru catalysts were calculated. • The different H sources (H 2 and solvent) in hydrogenolysis reaction were compared. • The hydrogenolysis route under different H-donor conditions was presented. Selective hydrogenolysis, the aromatic ether C-O bonds under mild conditions, is crucial for the valorization of lignin. In this context, the effects of H 2 and solvent on the hydrogenolysis of lignin model compounds over Ru catalysts were explored. With H 2 as hydrogen donor, the Ru/AC exhibited the highest activity for converting lignin model compounds into monomeric compounds, whereas H 2 led to low selectivity of aromatics. However, isopropanol was the good H-donor solvent, which could provide a large amount of active hydrogen to promote the cleavage of C-O bonds. Additionally, the yield of aromatics in isopropanol was higher than that under H 2 atmosphere. It could be ascribed to the fact that isopropanol is the protic solvent which displays Lewis basicity, and is a good H-bond donor and a good H-bond acceptor. The higher electron-releasing inductive effect of isopropanol made it easier to provide active hydrogen. Based on the experiments, the mechanism of benzyl phenyl ether hydrogenolysis in H 2 and isopropanol system was presented. [ABSTRACT FROM AUTHOR]

• Selective hydrogenation of aromatic rings in lignin model compounds over Ru/Nb 2 O 5. • H 2 rather than solvents provided the only hydrogen source in this reaction. • Hydrodeoxygenation reaction did not occur due to the acid loss of Ru/Nb 2 O 5. • The reaction route of the aromatic rings hydrogenation in DPE was presented. Selective aromatic ring hydrogenation is an important process for the valorization of lignin and designing the high active and selective catalyst is still a challenge. At present, it is reported that such catalysts generally have some shortcomings including strict reaction conditions, complicated catalyst preparation and low reaction efficiency. Herein, Ru/Nb 2 O 5 catalyst with the macropore structure prepared by an incipient wetness impregnation method could effectively promote the aromatic rings hydrogenation of various lignin-derived compounds under extremely mild condition (30 °C). The resulting aliphatic compounds with the high yield provided abundant raw materials for the production of fine chemicals and biofuels. In this case, further experiments revealed that it was H 2 rather than solvents provided the only hydrogen source. A relatively low bond energy of Ru0 in Ru/Nb 2 O 5 promoted the formation of active hydrogen from H 2. Due to the acid loss of Ru/Nb 2 O 5 catalyst, the hydrodeoxygenation reaction did not occur. Moreover, the catalyst was investigated under different influence parameters in order to obtain the optimal reaction conditions (30 °C, 3 MPa H 2). The application of Ru/Nb 2 O 5 catalyst may provide a promising approach to the value-added utilization of lignin-derived fragments. [ABSTRACT FROM AUTHOR]

• Sulfated HZSM-5 zeolite was prepared by dealumination, realumination and sulfation. • The introduced extra-framework Al affected the textural-acid properties of catalysts. • Sulfation of catalyst after re-introduced extra-framework Al enhanced LAs production. • The highest LAs and lowest coke yield were produced over SO 4 2−/DHZ5-A. Sulfated HZSM-5 zeolite prepared by dealumination, realumination and sulfation was used as the active mesoporous materials to promote the formation of light aromatics during catalytic reforming of volatiles from Shengli lignite pyrolysis. The results show that HCl-dealumination significantly increased the total pore volume (especially mesopores) and average pore size while reducing acid strength and amount of acid sites. The incorporation of the extra-framework Al species to HZSM-5 combined with SO 4 2− to form superacidic surface sulfate complex exhibited an increase in the yield of light aromatics and a decrease in the yield of coke in comparison with that of original HZSM-5. Among the modified catalysts, SO 4 2−/DHZ5-A (introduced the calcined Al 2 O 3 after HCl-dealumination and modified with (NH 4) 2 SO 4) with the acidity enhancement by sulfation obtained the maximum light aromatics yield of 27.3 mg/g and the lowest coke yield of 2.7%. The relationship between the physic-chemical properties of catalysts and the product distribution was proposed to understand the formation of light aromatics. [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]