Shenfu Sub-bituminous Coal Research Articles

Alkali-etched mesoporous zeolite beta supported Ni nanoparticles for the catalytic hydrocracking of Shenfu subbituminous coal to hydrocarbon-rich oils

The conversion of low-rank coal to hydrocarbons by catalytic hydrocracking (CHC) is an important process in chemical industry. However, obtaining hydrocarbon-rich oils directly from low-rank coal by precise removal of heteroatoms remains a huge challenge. Considering this fact, a novel bifunctional catalyst Ni10%@βE was prepared by alkali-etching and used for the CHC of Shenfu subbituminous coal (SC). Alkali-etching modified L/B acid distribution and promoted the formation of hierarchical pores in βE, which helps to improve the catalytic activity. Benzyloxybenzene can be selectively converted to benzene and toluene with a total yield of 184.3 mol% over Ni10%@βE. Under 1 MPa H2, 300 °C, and 2 h, the yield of SC-derived cracking oil increased from 8.6 % to 18.0 %, and the proportions of aliphatic hydrocarbons and arenes increased from 13.5 % and 41.9 % to 32.4 % and 63.6 %, respectively. Modification of βE by alkali-etching changes the H2 activation activity of Ni10%@βE. Synergetic transfer of H···H, δ+H···Hδ-, H+, and H· is the core of obtaining high-yield hydrocarbons from SC.

Cohesive components in coal and their cohesive mechanism during pyrolysis

The cohesive components in coals and their detailed structure were investigated. The results show that the caking index of Linfen fat coal after extracting by benzene and tetrahydrofuran (THF) decreases from 89 to 43. Through analyzes of FT-IR and synchronous fluorescence spectrometry, anthanthrene is considered as the primary cohesive component to determine the cohesiveness of coal, and it is 42.4 wt% in the extract by THF from fat coal. Meanwhile, 1-naphthol, the secondary cohesive component to influence the cohesiveness of coal, is 22.8 wt% in the extract by benzene from fat coal. The cohesive phenomenon of coal has a positive correlation with the maximum aromaticity index (fa), and the cohesive phenomenon cannot be found during pyrolysis when the maximum fa of samples is smaller than 0.640, which are found from SEM images and XRD spectra of the carbonized samples. Moreover, the addition of anthanthrene makes Shenfu sub-bituminous coal produce cohesive phenomenon that coal particles connect together through the formation of a uniform surface. Based on these findings, a possible cohesive mechanism of coal was proposed.

A low carbon footprint method for converting low-rank coals to oxygen-containing chemicals

Due to the urgent need to reduce CO2 emission and the shortage of petroleum, using coals especially low-rank coals as raw materials for producing chemicals has attracted much attention. Thermal extraction and oxidation in aqueous solution are efficient approaches for obtaining oxygen-containing chemicals from low-rank coals. However, yield of chemicals is limited and/or large amount of CO2 is released solely using either of the two technologies for converting low-rank coals. In this paper, a low carbon footprint method combining thermal extraction (TE) and oxy-cracking in dilute alkali aqueous solution for efficiently depolymerizing three low-rank coals, i.e., Xiaolongtan lignite (XLT), Xilinguole lignite (XLGL), and Shenfu sub-bituminous coal (SF), was proposed. The results indicate that considerable oxygen-containing compounds such as phenols, esters, and humic acids along with little CO2 emission can be obtained via the two-step depolymerization process. TE temperature significantly effects the dissolution of small molecular compounds. Comparing with XLT and XLGL, SF has lower TE and oxy-cracking activity. A good correlation between the oxy-cracking conversion of TE residues and their DTG peak temperature for the low-rank coals can be found. Therefore, the aforementioned approach is promising for high-value and low-carbon utilization of low-rank coals.

Structural characteristics of soluble organic matter in four low-rank coals

Four low-rank coals, Zhaotong lignite, Dayan lignite, Wucaiwan sub-bituminous coal and Shenfu sub-bituminous coal were sequentially dissolved in cyclohexane, acetone and methanol at 300 °C. An Orbitrap mass spectrometry coupled with an atmospheric pressure chemical ionization ion source was used to analyze the 12 thermal dissolution (TD) extracts from coals to obtain and compare the molecular distribution of soluble organic matter. Two statistical methods, principal component analysis and hierarchical clustering analysis, were used to mine the effective information from a large number of mass spectral data. The statistical results showed that the degree of coalification had greater effects on the structure and composition of TD extracts compared to the solvent. In-source collision-activated dissociation further elucidated the characteristics of molecular structure and revealed that most of O atoms distribute on alky chains.

Effect of thermal extraction on hydro-liquefaction property of residual coal

Thermal extraction (TE) of low rank coal with low boiling point solvent is an important approach to obtain organic chemicals, but it remains a great deal of thermal extraction residue (TER) due to low extraction yield. In this paper, Xilinguole lignite (XL) and Shenfu sub-bituminous coal (SF) were extracted by toluene and toluene/methanol mixed solvents at 250–350 °C to obtain TERs. Then the obtained TERs were hydro-liquefied to investigate their hydro-liquefaction property under mild conditions. By combination with the structural characterizations of TER and its liquefied products, it was found that TE can separate small molecular compounds, and improve the hydro-liquefaction performance of TER. Rising TE temperature and adding appropriate methanol to toluene can increase the TE yield and the oil + gas (O + G) yield of TER hydro-liquefaction, especially for XL which containing abundant oxygen functional groups. The effects of heat-induced relaxation of non-covalent bonding associated structure and solvent-induced cleavage of covalent bonds on the TE and the hydro-liquefaction of TER were discussed.

Effect of solvent extraction pretreatments on the variation of macromolecular structure of low rank coals

In order to understand the effects of solvent pretreatment on the inherent macromolecular structure of low rank coal, Xilinguole lignite (XLL) and Shenfu sub-bituminous coal (SFC) were extracted by tetrahydrofuran (THF) Soxhlet extraction, carbon disulfide/N-methyl-2-pyrrolidone (CS2/NMP) mixed solvent extraction and thermal dissolution, respectively. The extracted coals were characterized by diffuse reflection FT-IR spectroscopy (DRIFT), thermogravimetric analysis (TGA), mercury intrusion method (MI) and swelling ratio determination. The results indicated that the extraction resulted in the arrangement and reassociation of coal inherent macromolecules. THF Soxhlet extraction and CS2/NMP mixed solvent extraction can relax the macromolecular structure of coal to varying degrees by changing the non-covalent bond cross-linking, especially the distribution of hydrogen bond interactions. However, thermal dissolutions at high temperature mainly increased the covalent cross linking of coal macromolecules, especially for XLL. Swelling of all extracted coals was limited by Fickian diffusion, and the extracted coal showed lower swelling activation energy than the corresponding raw coals.

Thermal Dissolution of Shenfu Sub-Bituminous Coal Promoted by Lignin

Objective: Thermal Dissolution (TD) and Co-thermal Dissolution (CTD) of Shenfu (SF) coal and lignin were studied. The effect of temperature on the TD and CTD of SF coal and lignin was discussed. Method: The synergistic effect of SF coal and lignin in CTD was probed with the characterization of thermal dissolution soluble fraction by elementary analysis, FTIR and TG determinations. Result: The results suggested that TD activity of lignin was higher than that of SF coal. Both SF coal and lignin gave their maximal thermal dissolution yield (TDY) of 57.6 and 82.5%, respectively at 360oC. In CTD of SF coal and lignin process, the experimental values (expressed by EXP) of TDY and Thermal Dissolution Soluble Yield (TSY) were both higher than the corresponding calculated weighted mean values (expressed by CAL) of TDY and TSY obtained from the individual TD of SF coal and lignin, suggesting that there existed a synergistic effect in the CTD of SF coal and lignin. Both TDY and TSY in CTD were enhanced to maximal values at 360oC with (EXP-CAL) values of 3.4 and 7.5%, respectively. Conclusion: There were interactions between SF coal and lignin in the CTD process. The pyrolysis of lignin at low temperature may form some intermediates such as phenoxy radicals, and these intermediates can further cause depolymerization of coal, thus promoting the TD of coal.

Study on hydro-liquefaction kinetics of thermal dissolution soluble fraction from Shenfu sub-bituminous coal

Thermal dissolution (TD) of coal and hydro-liquefaction of the thermal dissolution soluble fraction (TDSF) with a high activity catalyst is one of effective high efficient hydro-liquefaction of coal techniques. In this study, a Chinese Shenfu (SF) sub-bituminous coal was thermally dissolved, and the TDSF obtained was further hydro-liquefied with Ni–Mo-S/Al2O3 catalyst. Based on the hydro-liquefaction results, a model including series and parallel reactions was established for the hydro-liquefaction of TDSF catalyzed by Ni–Mo-S/Al2O3, and the regressive reactions were ruled out in the model. From the kinetic parameters calculated, it suggested that the regressive reactions including the char formation reactions were negligible in the hydro-liquefaction of TDSF catalyzed by Ni–Mo-S/Al2O3. The reactions of TDSF to preasphaltene and preasphaltene to oil+gas predominated the formation of oil+gas. Ni–Mo-S/Al2O3 could decrease the activation energy of preasphaltene to oil+gas reaction, thus promoting the formation of oil and gas in the catalytic hydro-liquefaction of TDSF.

Study on the stability of hydro-liquefaction residue of Shenfu sub-bituminous coal

The stability of direct coal liquefaction residue (DCLR) has significant effects on the DCL technology and the utilization of DCLR. In this paper, the pyrolysis behaviors of the DCLR from 6t/d Shenhua BDU technology and its components including tetrahydrofuran soluble (THFS) and insoluble (THFI) were investigated by thermogravimetric analysis (TGA). Then, its thermal stability and THFS hydrogenation activity were studied by thermal treatment and hydrogenation treatment, respectively. Results show that DCLR and its components have different pyrolysis behaviors. Inorganic components existed in DCLR and THFI show a catalytic effect on the pyrolysis of organic matrix, but THFS inhibits the decomposition of carbonates in DCLR. The weight loss of THFI mainly results from the decomposition of carbonates and the dehydrogenation rather than the cracking of organic matrix. The thermal stability of DCLR mainly depends on the hydrogen donating ability and the solvency of solvent, and THFI formed in the thermal treatment mainly originates from the condensation between oxygen containing functional groups. The spent catalyst in DCLR can inhibit the condensation of THFS, which is more prone to form THFI at lower temperature.

Palaeoenvironmental and evolutionary implications of fossil frog assemblages from the South African west and south coasts

The oxidative depolymerizations of Shenfu subbituminous coal (SSBC) and its thermal dissolution insoluble (TDI), which obtained by thermal dissolution (TD) in 1-methylnaphthalene at 320 °C, were investigated with H2O2 aqueous solution as oxidant under different conditions. Their products were characterized by FTIR, ultimate analyses and acidic functional groups determination. Further, the detailed comparison of oxidative depolymerizations of SSBC and its TDI was carried out with 20% H2O2 at 60 °C. The water solubles (WSs) were esterified, and subsequently analyzed by GC/MS in order to understand the macromolecular structural features of SSBC. The results revealed that compared with SSBC, the TDI contained more phenolic hydroxyls and showed higher oxidation reactivity. It suggested that the phenolic hydroxyl should be the active site of oxidative depolymerization, and thermal dissolution generated substantial phenolic hydroxyls in TDI by the rupture of Cal–OAr. The WS from the oxidation of SSBC mainly consists of monocyclic aromatic acids, while the WS from TDI contains much amount of alkanoic acids and α,ω-dicarboxylic acids. Especially the substantial oxalic acid and malonic acid identified in the WS from TDI suggested that significant amount of the aromatic rings in the macromolecules of SSBC could be coupled directly or connected by monomethylene bridge.

Dynamics of Holocene Saharan dust sources and transport

The oxidative depolymerizations of Shenfu subbituminous coal (SSBC) and its thermal dissolution insoluble (TDI), which obtained by thermal dissolution (TD) in 1-methylnaphthalene at 320 °C, were investigated with H2O2 aqueous solution as oxidant under different conditions. Their products were characterized by FTIR, ultimate analyses and acidic functional groups determination. Further, the detailed comparison of oxidative depolymerizations of SSBC and its TDI was carried out with 20% H2O2 at 60 °C. The water solubles (WSs) were esterified, and subsequently analyzed by GC/MS in order to understand the macromolecular structural features of SSBC. The results revealed that compared with SSBC, the TDI contained more phenolic hydroxyls and showed higher oxidation reactivity. It suggested that the phenolic hydroxyl should be the active site of oxidative depolymerization, and thermal dissolution generated substantial phenolic hydroxyls in TDI by the rupture of Cal–OAr. The WS from the oxidation of SSBC mainly consists of monocyclic aromatic acids, while the WS from TDI contains much amount of alkanoic acids and α,ω-dicarboxylic acids. Especially the substantial oxalic acid and malonic acid identified in the WS from TDI suggested that significant amount of the aromatic rings in the macromolecules of SSBC could be coupled directly or connected by monomethylene bridge.

Oxidative depolymerization of Shenfu subbituminous coal and its thermal dissolution insoluble fraction

The oxidative depolymerizations of Shenfu subbituminous coal (SSBC) and its thermal dissolution insoluble (TDI), which obtained by thermal dissolution (TD) in 1-methylnaphthalene at 320°C, were investigated with H2O2 aqueous solution as oxidant under different conditions. Their products were characterized by FTIR, ultimate analyses and acidic functional groups determination. Further, the detailed comparison of oxidative depolymerizations of SSBC and its TDI was carried out with 20% H2O2 at 60°C. The water solubles (WSs) were esterified, and subsequently analyzed by GC/MS in order to understand the macromolecular structural features of SSBC. The results revealed that compared with SSBC, the TDI contained more phenolic hydroxyls and showed higher oxidation reactivity. It suggested that the phenolic hydroxyl should be the active site of oxidative depolymerization, and thermal dissolution generated substantial phenolic hydroxyls in TDI by the rupture of Cal–OAr. The WS from the oxidation of SSBC mainly consists of monocyclic aromatic acids, while the WS from TDI contains much amount of alkanoic acids and α,ω-dicarboxylic acids. Especially the substantial oxalic acid and malonic acid identified in the WS from TDI suggested that significant amount of the aromatic rings in the macromolecules of SSBC could be coupled directly or connected by monomethylene bridge.

Thermolysis of biomass-related model compounds and its promotion on the thermal dissolution of coal

The thermolysis of biomass-related model compounds was carried out and its promotion on the thermal dissolution of coal was probed in this study. Benzyl phenyl ether was easily to pyrolyze than dibenzyl ether, and the thermolysis conversions of benzyl phenyl ether and dibenzyl ether were 98.3 and 32.4% at 360 °C respectively. The product analysis of the thermolysis suggests that the pyrolysis of the biomass-related model compounds follows the radical reaction route and some phenyl oxygen free radicals are formed in the process. Addition of 2% phenol could obviously increase the thermolysis conversion of dibenzyl ether, suggesting that the free radicals formed from phenol can promote the pyrolysis of dibenzyl ether. Addition of 10% benzyl phenyl ether could obviously promote the thermal dissolution of Shenfu sub-bituminous coal, and the thermal dissolution yield of Shenfu sub-bituminous coal could be increased by 20.8% at 360 °C. The enhancement of thermal dissolution of Shenfu coal by benzyl phenyl ether can be attributed to that the benzyloxy and phenoxy radicals formed from the thermolysis of benzyl phenyl ether attack the coal molecules, thus promoting the depolymerization of coal.

Study on the Use of the Thermal Dissolution Soluble Fraction from Shenfu Sub-bituminous Coal in Coke-Making Coal Blends

Thermal dissolution (TD) of a Chinese Shenfu sub-bituminous coal (SFSBC) at different conditions was carried out, and the effects of the addition of a thermal dissolution soluble fraction (TDSF) in coke-making coal blends on the properties of coke were evaluated in this study. The results suggested that SFSBC gave the highest thermal dissolution soluble yield (TDSY) of 61.9% in 1-methylnaphthalen (1-MN) at 360 °C. Then, the TDSY decreased to 44.8% when the TD temperature increased to 380 °C because of pyrolysis and condensation reactions of coal taking place at this temperature. Polar solvents gave larger dissolution ability to SFSBC than nonpolar solvents. The properties of TDSFs obtained from different conditions were quite different. At the TD temperature of 320–360 °C, the TDSF in 1-MN at a higher temperature contained more −OH groups with a narrow thermoplastic temperature interval compared to that at a lower temperature. The TDSFs in polar solvents crude methyl naphthalene oil (CMNO) and 1-MN added with 20% methanol at 320 °C contained less amount of −OH groups and more aromatic components, thus giving a wide thermoplastic temperature interval than the TDSF obtained in 1-MN. The 5 wt % TDSF addition in the coke-making coal blends decreased the softening temperature of the coal blends, thus improving the coke quality. Blending the TDSF obtained at a lower temperature or in polar solvents in coke-making coal blends had better effects on improving the quality of coke.

Studies on Macrostructure of Shenfu Sub-bituminous Coal

Tetrahydrofuran (THF) was used to extract Shenfu sub-bituminous coal and Shenfu sub-bituminous coal macrostructure simulated was structured. The extraction fractions and the residue were analyzed by GC/MS and solid-state 13C NMR respectively, from which abundant structural information of Shenfu sub-bituminous coal was obtained, such as f a , f a c , f a l , f a H etc. In addition, a hybrid genetic algorithm was presented to simulate approximately the complicated structure of Shenfu sub-bituminous coal through the structural fragments and functional groups.

The Effect of Pretreatment with H2O2 on the Oxidation of Shenfu Subbituminous Coal with NaOCl

Shenfu subbituminous coal (SFSBC) and pretreated SFSBC with H2O2 were subjected to oxidation with NaOCl at 30°C for 5 h. The results show that the pretreatment with H2O2 significantly increased the yields of water-soluble species (WSS), especially benzene carboxylic acids (BCA) and long-chain alkanedioic acids (LCADA), but substantially inhibited the formation of chloro-substituted alkanoic acids. The introduction of oxygen functional groups to SFSBC by the pretreatment (LCADA) could be responsible for the increase in the yields of WSS, especially BCA and LCADA.

Co-liquefaction of rice straw and coal using different catalysts

Co-liquefactions of a Chinese Shenfu sub-bituminous coal (SFSBC) and rice straw (RS) over four different coal liquefaction catalysts were carried out and the co-liquefied product preasphaltene (PA) was characterized by elemental analysis, FTIR and gel permeation chromatograms (GPC) measurements. It was found that the four catalysts gave different catalytic activities in the liquefaction of SFSBC and RS alone. CoMo/Al2O3 and SO42-/ZrO2 promoted the oil formation for RS liquefaction due to their solid acidic property, but FeS+S gave the highest catalytic activity for the liquefaction of SFSBC among the four catalysts used in this study. There existed a positive synergistic effect in the co-liquefaction of SFSBC and RS, and the main synergistic interaction was reflected by the promoted formation of oil and PA. The catalytic activities of the four catalysts in the co-liquefaction were quite different from their catalytic activities in the individual liquefaction of SFSBC and RS. FeS gave the lowest catalytic activity for the coal liquefaction alone among the four catalysts, but had the highest promotion to the synergistic effect in the total yield of liquefaction products in the co-liquefaction of SFSBC and RS. SO42-/ZrO2 diminished this synergistic effect for the co-liquefaction of SFSBC and RS due to its solid acidic property. It was found that the four catalysts used have higher catalytic activity for the PA, which is from coal liquefaction and converting this part of PA into AS and oil fraction. The average molecular weights of PAs from SO42-/ZrO2 and CoMo/Al2O3 catalysts were lower than those of PAs from FeS and FeS+S catalysts, suggesting that the catalytic hydrogenation activities of SO42-/ZrO2 and CoMo/Al2O3 are higher than those of FeS and FeS+S catalysts.

Effect of inorganic matter on reactivity and kinetics of coal pyrolysis

Two Chinese coals, Shenfu subbituminous coal and Huolingele lignite, were used to investigate the effect of mineral matter in coal on reactivity and kinetic characteristics of coal pyrolysis. The experiments were carried out by using thermogravimetry to check the pyrolysis behavior of raw coal, HCl/HF demineralized coal and demineralized coal with inorganic matter (CaO, K 2CO 3 and Al 2O 3) added, respectively. The results showed that inherent mineral in coal had no evident effect on the reactivity and kinetics of coal pyrolysis. CaO, K 2CO 3 and Al 2O 3 all had a catalytic effect on the reactivity of coal pyrolysis, their effects were closely related to temperature region and coal types. The pyrolysis process of all the samples studied can be described by three independent first order kinetic model. Addition of inorganic matter the activation energy decreased and the characteristic temperature of coal changed.