Search

A hierarchical porous zeolite Y (HPZY) supported Ni–Co catalyst was prepared by pyrolyzing nickel tetracarbonyl and using modified deposition-precipitation to highly disperse Ni–Co nanoparticles onto HPZY. Hecaogou subbituminous coal was effectively ethanolyzed to obtain ethanol-soluble portion (ESP E) in a high yield (21.2%). Sequentially, ESP E was subjected to the deep hydroconversion (DHC) over prepared Ni 10% -Co 3% /HPZY at 150 °C under 4 MPa of initial hydrogen pressure for 24 h in n -heptane to produce deeply hydroconverted ethanol-soluble portion (ESP DHC). All the group components in ESP E , including arenes (53.3%), oxygen-containing organic compounds (24.4%), and nitrogen-containing aromatics (2.3%) were completely converted to chain alkanes (CAs, 36.8%), cyclanes (39.2%), and hydroarenes (24.0%). In addition, the hydroisomerization of CAs and hydroreforming of aromatic rings (ARs) in ESP DHC are predominant over Ni 10% -Co 3% /HPZY with more accessibility of active sites under mild conditions. Ni 10% -Co 3% /HPZY with suitable acidity and highly dispersed Ni–Co nanoparticles can effectively activate H 2 to H⋯H and further heterogeneously split H⋯H to H+ and H−. H⋯H and H+ transfer plays crucial roles in the DHC of ESP E. Correspondingly, the related mechanisms are evidenced by the DHC of 2,2′-oxydinaphthalene (ODN) over Ni–Co/HPZY. Ni 10% -Co 3% /HPZY maintains high activity for the DHC of ODN under mild conditions after 4 recycles. • Modify CZY by fluorine-alkaline cascaded treatment to obtain HPZY. • Ni–Co/HPZY has an outstanding catalytic activity and stability for the DHC of ESP E. • Ni–Co/HPZY effectively induced the formation of H+, H−, and H⋯H during the DHC. • All of group components in ESP E were completely converted to CAs, cyclanes, and HAsII. [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]

In‐depth understanding of coal conversion processes is a key step for clean and efficient utilization of coals in chemical industry. Currently, most analytic methods aim to evaluate heteroatom release on the entire molecules. However, the production of value‐added chemicals from complex mixtures like coals are technically demanding which inevitably requires in‐depth fundamental knowledge of the treatment processes for coals. In‐source collision‐activated dissociation (ISCAD), a mass spectrometric method, can obtain details of aromatic cores and was employed in this work to provide in‐depth understanding of the catalytic conversion process of a low‐rank coal under different solvent conditions. Different heteroatom release patterns on aromatic and alkyl locations were observed for the solvents. Each solvent exhibited a characteristic preference over deoxygenation/denitrogenation on aromatic versus alkyl positions. Such preference is important for developing a desired catalytic treatment for a targeted heteroatom release. Overall, this study provides novel insights in catalytic heteroatom release processes during coal conversion that may be critical for the production of value‐added chemicals from coals. [ABSTRACT FROM AUTHOR]

• MMNs of IEP is analyzed by multiple non-destructive technical strategies. • The MMNs in IEP consists of aliphatic (59.6%) and aromatic carbons (39.3%). • Pyrolysis mechanisms are analyzed by correlation IEP E and IEP FP at the molecular level. • Pyrolysis of MMNs produce organic species by cleaving the >C– X bridge bonds. The organic macromolecular networks (MMNs) from Hecaogou subbituminous coal (HSBC) were investigated by multiple technical strategies, including SEM, 1H and 13C NMR, FTIR, XPS, TG/DTG, and flash pyrolysis (FP) technology. The pyrolysis mechanisms of MMNs were effectively investigated to release organic volatile species between ethanolyzed (E) inextractable portion (IEP E) and FP of IEP (IEP FP) at molecular level. In detail, solid-state 13C NMR analysis shows that carbon skeleton of IEP mainly consists of aliphatic (59.6%) and aromatic carbons (39.3%). XPS analysis shows that the >C–OH groups, pyrrolic, and sulfonic sulfurs in IEP surface are the most abundant O-, N-, and S-containing species. FTIR analysis proves that the weak- and medium >C al - X (X denotes C al <, H, O-, N<, and S-) in IEP could be cleaved during ethanolysis. Based on the destructive analysis with TG/DTG, the structure of MMNs in IEP features dissociating small molecular groups with different types >C al - X bridge bonds, which facilitates the release of organic volatile species and then prevents the thermal condensation during pyrolysis process. Additionally, the relative content (RC) in IEP E of various organic species are as follows: chain alkanes (CAs, 18.5%), alkenes (0.9%), arenes (11.9%), and oxygen-containing organic compounds (OCOCs, 58.4%), while the RC of CAs (46.8%), alkenes (17.5%), arenes (16.8%), and OCOCs (13.8%) in IEP FP. Comprehensive investigation and detailed analysis the distribution of organic species further prove that the active hydrogen (H‧) cleave the >C al - X of MMNs at different positions during the pyrolysis process to obtain more CAs, alkenes, alkanols, and phenols at molecular level. [ABSTRACT FROM AUTHOR]

[Display omitted] • PO increases the yields of BCAs, ADAs, and AAs sharply. • PO is more effective to afford BCAs with more carboxylic groups. • PO provides more active sites to significantly raise the yield of AAs and ADAs. • PO promotes the formation of –COOH from other oxygen-containing groups or bonds. • The formation of –COOH is the critical to increase the yield of oxidation products. Environmental concerns have led researches to investigate carbon neutral and sustainable strategies to satisfy well-being of present and future generations, in which coal oxidation becomes a promising approach to achieve this goal. In this study, Yima long flame coal (YLFC) was subjected to ruthenium-ion-catalyzed oxidation (RICO) after peroxidation with H 2 O 2 (PO). The results indicate that the organic matter in YLFC is mainly oxidized into benzenecarboxylic acids, accounting for 70.36% of all the oxidation products, and the yields of the valuable resulting carboxylic acids are significantly elevated by PO from 12.99 wt% to 35.06 wt%, leading to a higher utilization of carbon and lower CO 2 emission. Moreover, PO can enhance remarkably the reactivity of the macromolecular precursors of coals, especially highly condensed aromatic species to produce benzenepentacarboxylic acid and mellitic acid more efficiently with a 20-fold increase and 200-fold increase, which is ascribed to the formation of carboxyl groups from other oxygen-containing groups or bonds in coals via PO. The reactive intermediates OH and OOH generated from H 2 O 2 decomposition can attack the carbon atom of alkyl side chains, ether bonds, C=O bonds, and the bridged linkages to undergo a preliminary degradation of macromolecular networks in coals and produce more active sites for the subsequent RICO, leading to the yield and species number increase of carboxylic acids via PO. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni/ZTMS prepared from a coal fly ash proved to be active for the CHC of a waster oil. • More than 95% of the waster oil was converted to cyclanes over Ni/ZTMS at 240 °C. • Three birds with one stone: reducing aromatics, removing HAs, and increasing cyclanes. • The synergism of H⋯H and H+ plays crucial role in the CHC of the waster oil to cyclanes. An organic waster oil (OWO) from petroleum processing was extracted with petroleum ether (PE) to PE-extractable portion (PEEP) and extraction residue 1 (ER 1), which was extracted with isometric acetone/carbon disulfide mixed solvent (MS) to MS-extractable portion (MSEP) and extraction residue 2 (ER 2). A zeolite topology molecular sieve (ZTMS) was prepared from coal fly ash. Ni/ZTMS was prepared by loading Ni into ZTMS. Both PEEP and MSEP were subjected to catalytic hydroconversion (CHC) over Ni/ZTMS in n -hexane under 4 MPa of initial hydrogen pressure (IHP) at 240 °C for 2 h. The results show that most of arenes, hydroarenes, and oxygen-containing organic compounds (OCOCs) and all the nitrogen-containing aromatics (NCAs) in PEEP and all the arenes and NCAs together with most of OCOCs in MSEP were converted to cyclanes. To understand the mechanism for the CHC of PEEP and MSPE from the OWO, 2-phenylphenol (PP) was used as the OWO-related model compound. As a result, PP was completely converted and the yield of target product bicyclohexane (BCH) reached to 97.7% over Ni/ZTMS in n -hexane under 4 MPa of IHP at 240 °C for 2 h. The characterizations of Ni/ZTMS and time profiles of the products from the CHC of PP reveal that Ni/ZTMS can activate H 2 to H⋯H and heterolytically cleave H 2 to relatively mobile H+ and immobile H-; H⋯H addition to benzene ring in PP causes PP hydrogenation, while H+ addition to the oxygen in the resulting 2-phenylcyclohexanol (PCH) and 2-cyclohexylcyclohexanol (2-CHCH) induces the dehydroxylation of PCH and CHCH. [ABSTRACT FROM AUTHOR]

[Display omitted] • Extraction and subsequent E can release many SSs from HSBC and IEP. • The predominant CS in HSBC and its R s are aliphatic and aromatic carbons. • The main oxygen occurrence are >C-OH and >C-O- moieties in HSBC and its R s. • R S , especially R IEP , can be further used in pyrolysis or porous material precursors. The structural features (SFs) of Hecaogou subbituminous coal (HSBC) and its residues (R s) were investigated with non-destructive tools, including scanning electron microscope (SEM), solid-state 13C nuclear magnetic resonance (SS 13C NMR), Fourier transform infrared spectrometer (FTIRS), and X-ray photoelectron spectrometer (XRPES), combined with thermogravimetric analyzer (TGA) and flash pyrolysis (FP). SS 13C NMR analysis shows that both HSBC and its R s consist of aliphatic, aromatic, and carbonyl carbon species. The total content of aliphatic carbon species in the R s is lower than that in HSBC, but the content of carbonyl carbon species is basically unchanged. In both HSBC and its R s, aliphatic linkages connect 3–5 aromatic rings (ARs) and the number of substituents on each AR is up to 2 on average. Based on the semi-quantitative analysis with FTIRS and TGA, cleavaging weak- and medium-strength covalent bonds (>C al -X-, X denotes H, N, S, or >C al) should be the main reactions during the ethanolysis of HSBC and its inextractable portion. The analysis with XRPES indicates that the main oxygen-, nitrogen-, and sulfur-containing moieties are >C-O- groups, pyrrolic, and aromatic and sulfonic sulfurs, respectively, on the surface of HSBC and its R s. Considerable amounts of alkanes and alkenes were released and non-substituted arenes are the main arenes released from the FP of HSBC and its R s. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical Ga/Al HZSM-5 exhibits high BTEXN yield at 600 °C. • Ga and HZSM-5 presented a strong synergy during the formation of aromatics. • Ga/Al HZSM-5 keep high stability during 6th cycle reactions. • Multifunctional catalysts promote the formation of H 2 by dehydrogenation. HZSM-5 was hydrothermally synthesized by Ga substitution to regulate the texture properties for light aromatics such as benzene, toluene, ethylbenzene, xylenes and naphthalene (BTEXN) during the lignite volatiles catalytic upgrading process. High BTEXN yield was obtained over xGa/H5(A) (added NaOH in crystallization) and the value increased with raising the amount of Ga incorporation when the Ga content was<1.26 g. 1.26 Ga/H5(A) (1.26 g Ga(NO 3) 3) displayed the highest yield of BTEXN (29.3 mg/g-daf coal) since Ga species and acidic protons promoted the aromatization process. However, excessive Ga brought a negative effect on the production of aromatics due to the weakened synergistic effect between Ga species and acid sites of H5. Additionally, 1.26 Ga/H5(A) with the interconnected meso -micropores and moderate acidity distribution exhibited excellent reaction stability during the 6 cycle experiments. xGa/H5(A) provided a potential prospect for enhancing the BTEXN formation during catalytic upgrading of lignite pyrolysis volatiles. [ABSTRACT FROM AUTHOR]

• Monitoring catalytic conversion of coal using mass spectrometry. • Single-heteroatom loss method well fits denitrogenation patterns. • Aromatic cores of compounds between 300 and 400 Da show similarity in ring size. The structure-reactivity relationship during catalytic reactions for coal has been extensively simulated by using model compounds. However, the direct study of structure-reactivity relationship is not sufficient for coal, the complex mixture, partially due to the challenging task of monitoring catalytic reactions in complex mixtures at the molecular level. In this study, a tandem mass spectrometry (MS) approach was designed for selective observation of catalytic single-atom denitrogenation and deoxygenation reactions of a coal. According to the tandem MS data, structure of aromatic cores, total carbon number in alkyl chains, heteroatom release efficiency and preference of heteroatom removal on aromatic cores versus alkyl chains were explored and compared to reveal the relationship between heteroatom release pattern and molecular structure. Structure-reactivity relationship was not clearly observed in deoxygenation patterns due to majorities of molecules contain multiple oxygen atoms. However, structure-reactivity relationships were revealed in denitrogenation patterns due to the presence of single nitrogen atom in most nitrogen-containing molecules. [ABSTRACT FROM AUTHOR]

In coal chemistry, thermal dissolution (TD) is an effective processing technique to obtain soluble components from coal by using organic solvents under a certain pressure and temperature. Exploring molecular structures of the TD extracts of low-rank coal is of great importance for eco-friendly and value-added utilization in chemical industry. To well elucidate the structural information of components in coal, higher-energy collisional dissociation (HCD) specific to Orbitrap mass spectrometry was applied to analyze four TD extracts of a subbituminous coal. Alkyl chains of aromatic compounds can be removed from aromatic cores during a HCD process, allowing determination of the distribution of heteroatoms in either aromatic cores or alkyl chains. Both double bond equivalent value and carbon number of precursor ions (whole molecules) and the corresponding fragment ions (aromatic cores) obtained via a HCD process were used to evaluate the relationship between aromatic cores and alkyl chains for compounds in coal. With the increase of molecular weight, compounds in coal exhibited different distributions for aromatic cores and alkyl chains. From 200 Da to 300 Da, the increase of carbon number mainly contributed to the formation of condensed aromatic cores. However, from 300 Da to 400 Da, it was attributed to the formation of both aromatic cores and alkyl chains. In addition, heteroatom distribution index indicated that a higher TD yield of heteroatom-containing compounds would be obtained via solvents with a smaller molecular size and nitrogen-containing aromatics would be enriched by using TD solvents containing aromatic ring. [ABSTRACT FROM AUTHOR]

• Hydropyrolysis of coal produces more BTEXN than pyrolysis over HZSM-5. • H 2 promoted the form of reactive H radicals during pyrolysis conversion. • H 2 promotes the dissociation of C C bond in coal structure. • Relationship was established between the coal ranks and released BTEXN. Light aromatics (LAs) can be produced from catalytic fast pyrolysis or catalytic hydropyrolysis of coals, which represents one of the most promising alternatives to liquid fossil fuels. In this work, catalytic upgrading of volatiles was performed in a drop bed reactor under an inert atmosphere (Ar) and a reducing atmosphere (H 2) over HZSM-5. H 2 is consumed during hydropyrolysis process. Coal samples were hydropyrolyzed to produce higher gas yield and lower content of residual char. The presence of H 2 can yield more reactive H radicals which acts on C–O bond and C–C bond during pyrolysis conversion of coal. The released behavior of LAs is closely related to coal structure to a large extent. Catalytic pyrolysis of low rank coals produces more BTEXN than that of high rank coals. The H 2 accelerated the formation of LAs, especially for low rank coals. A correlation was established between the aromatic-C structure of coals and LAs through the characterization and semi-quantitative analysis of coal structure and tar. The co-effect of HZSM-5 and H 2 showed the highest yield of LAs during the low rank coals pyrolysis. The organic-oxygen species and C–H groups in the upgraded tar decreased gradually with the increase of coalification degree. Meanwhile, high aromaticity in coal can cause a poor pyrolysis reactivity, which may have influenced the secondary cracking reaction over HZSM-5. [ABSTRACT FROM AUTHOR]