Liquefaction Residue Research Articles

The Amorphous Alloy-catalyzed Hydroconversion of Demineralized Shengli Coal Liquefaction Residue Under Microwave Irradiation

Microwave-assisted hydroconversion of demineralized Shengli lignite liquefaction residue (DMSLLR) over Ni-B/SiO2 in methanol was investigated under mild conditions. The results show that Ni-B/SiO2 significantly catalyzed DMSLLR hydroconversion by increasing the methanol-extractable fraction of hydroconverted DMSLLR to 87.7% over Ni-B/SiO2 from 62.3% without catalyst. The yields of alkanes, hydroarenes, alkyl arenes, non-substituted arenes, organooxygen compounds, and organosulfur compounds from catalytic hydroconversion of DMSLLR are drastically higher than those from non-catalytic hydroconversion of DMSLLR. Benzo[ghi]perylene is the most abundant condensed arenes detected.

The Isolation of Condensed Arenes from Shenmu-Fugu Coal Liquefaction Residue

Shenmu-Fugu subbituminous coal liquefaction residue was exhaustively extracted with petroleum ether (PE) to afford PE-extractable fraction (PEEF), which was then eluted with petroleum ether through a silica gel-filled column. The PEEF and eluates were analyzed with a gas chromatographer/mass spectrometer and a Fourier transform infrared spectrometer. As a result, a number of 4- to 7-ring condensed arenes (CAS) were detected in the PEEF series of 4- to 6-ring CAs along with long-chain alkanes were isolated from the PEEF by column chromatography.

Hierarchical porous carbon catalyst for simultaneous preparation of hydrogen and fibrous carbon by catalytic methane decomposition

Direct coal liquefaction residue was used as the precursor for preparing hierarchical micro-/macro-mesoporous carbon by KOH activation with addition of Al2O3, and the resultant carbon AlRC was used as the catalyst for catalytic methane decomposition. The results indicate that the carbon AlRC shows excellent methane conversion, up to 61% after 10 h. Besides hydrogen production from methane decomposition, fibrous carbons were formed on the AlRC catalyst, which is different from other carbon catalysts. The investigations of the formation and growth of the fibrous carbon on the carbon catalyst and its catalytic performance indicated that the formed fibrous carbon contribute to the high methane conversion of AlRC catalyst.

Efficiently trapping asphaltene-type materials from direct coal liquefaction residue using alkylsulfate-based ionic liquids

Alkylsulfate-based ionic liquids (ILs) were synthesized and used as solid–liquid separation solvents to extract asphaltene-type materials from direct coal liquefaction residue (DCLR). Among the ILs employed, tetraethylammonium ethylsulfate ([E4N][ESO4]) was proved to be a potential solvent for trapping asphaltene-type materials from DCLR due to the higher extraction yield and the lower H/C atomic ratio of the extract. N-methyl-2-pyrrolidone (NMP) was added to reduce the viscosity of [E4N][ESO4]. It also increased the extraction yield and decreased H/C atomic ratio of the asphaltene-type materials. The mechanism of extraction might be concluded that the interactions are formed between ILs or [E4N][ESO4]/NMP mixed solvents and asphaltene-type materials, which disturbs the interactions between DCLR and leads to the dissolution of asphaltene-type materials into solvents. The obtained asphaltene-type materials possessed low H/C atomic ratios, high aromaticities, no ashes and no quinoline insolubles, which meet the requirements of preparing carbon materials.

Synergic effect of methanol and water on pine liquefaction

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

Synthesis of a carbon nanofiber/carbon foam composite from coal liquefaction residue for the separation of oil and water

A carbon nanofiber (CNF)/carbon foam composite was fabricated from coal liquefaction residue (CLR) through a procedure involving template synthesis of carbon foam and catalytic chemical vapor deposition (CCVD) treatment. The high solubility and high pyrolysis yield make CLR a promising carbon precursor for the synthesis of carbon materials using the template method. The carbon foam has cell size of about 500μm and a porosity as high as 95vol.%. Fe species naturally present in the CLR disperse homogeneously on the surface of the carbon foam acting as a catalyst in the CCVD process. After the CCVD treatment, the whole surface of the carbon foam is covered by entangled CNFs with external diameters of 20–100nm and lengths of several tens of micrometers. The obtained CNF/carbon foam composites are effective selective adsorbents in the separation of oil and water, through a combination of hydrophobicity and capillary action.

An overview of conversion of residues from coal liquefaction processes

AbstractDirect coal liquefaction (DCL) is a process for converting coal to synthetic oils, which can be refined to make transportation fuels. Residue from this process contains inorganic material such as mineral matter originating from the coal and catalysts, and organic matter such as unconverted coal, heavy oils, pre‐asphaltenes and asphaltenes. The conversion of these DCL residues to lighter, high‐value products is an important step in helping to make this technology both commercially viable and environmentally acceptable. This paper provides an overview of the physico‐chemical characteristics and processing options available for coal liquefaction residues and compares and contrasts them to those of petroleum residues.Residue properties vary considerably, since they are highly dependent on feed coal, process configuration and operating conditions. Determination of composition and structural parameters of products derived from residue conversion can help determine their stability, coking and solvent hydrogen donating ability. Thermal conversion processes such as visbreaking and gasification offer the greatest promise for handling these heavy materials. The conversion chemistry, reactivity and kinetics of residue gasification are not well‐understood but are important in optimising hydrogen production for the process.The literature has been comprehensively reviewed to provide characteristics and properties of residues and their potential for conversion. In addition, the potential for producing high‐value carbon products from residues is briefly discussed.

Ni doped carbons for hydrogen production by catalytic methane decomposition

Ni doped carbons were prepared from raw coal and direct coal liquefaction residue (CLR) by KOH activation with addition of Ni(NO3)2, and used for catalytic methane decomposition (CMD) to produce hydrogen. The catalytic activity of the Ni doped carbon for CMD was compared with those of metal catalysts (Ni/SiO2 and Ni/Al2O3), coal- and CLR-based carbons, and Ni-carbon catalysts prepared by traditional impregnation and precipitation methods. The results show that the Ni doped carbon has higher and more stable activity than the metal and carbon catalysts at 850 °C. The preparation method for Ni doped carbons can make full use of the reducibility of the carbon composition and simplify the traditional synthesis process. The Ni content and the morphology of carbon deposits produced during CMD have a great effect on the catalytic activity of the Ni doped carbon.

Hierarchical porous carbons prepared from direct coal liquefaction residue and coal for supercapacitor electrodes

Hierarchical porous carbons were prepared from a coal liquefaction residue (CLR) and two coals, Shenhua (SH) coal with low and Shengli (SL) coal with high ash content, by KOH activation with the addition of some additives, and used as the electrode for supercapacitors. Two metal oxides (MgO and Al2O3) and three organic materials (sugar, urea and cetyltrimethylammonium bromide) were used as the additives, to investigate their effects on the structure and capacitive performance of the resultant carbons. The results show that the metal oxide and/or its salt formed by the reaction with KOH can serve as space fillers of nanopores in the carbonized carbon, while the gases produced by the decomposition of the organic additive can develop and/or widen some pores. Both help the carbon produced from CLR or the SH coal with low ash content to have additional meso- and macropores, but destroy the structure of the carbon from the SL coal with high ash content. Compared with the carbon without any additive, the optimized hierarchical porous carbon with each additive shows a smaller equivalent resistance, much higher capacitance in a wide range of charge–discharge rates and excellent cycle stability when the carbon was used as supercapacitor electrode.

Petrology and structural studies in liquefaction reactions of Late Permian coals from Southern China

Three coals from South China, having high contents of vitrinite, liptinite, hydrogen, volatile matter, and high H/C atomic ratios, were subjected to liquefaction in tubing-bomb microreactors at 430°C for 1h with tetralin, hydrogen, and iron sulfate catalyst. The optical characteristics of the liquefaction residues were studied by white-light and fluorescence microscopy. A comparative study on the chemical structural features of the raw coals and their respective liquefaction residues was conducted by Fourier transform infrared spectroscopy (FTIR) and flash pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The liquefaction conversions were in the range of 79.0–87.1% (daf basis) under the conditions used. The optical examination of the liquefaction residues indicated that all of the liptinite and most of the vitrinite have reacted. For Dahebian coal, the observed liquefaction conversion was greater than the total vitrinite and liptinite content, indicating that some of the inertinite macerals must have participated in the reaction. Anisotropic semicoke was observed in the residue. Both FTIR and Py-GC/MS techniques showed that aliphatic groups, oxygen-containing functional groups, alkylbenzenes, and alkylphenol have reacted in liquefaction. C2-naphthalene and C3-naphthalene are main constitutions in residues.

The Influence of Process Factors on Liquefaction Residue Rate of Wood Packaging Waste

In order to improve the utilization rate and the added value of wood packaging waste as well as broaden the applications of wood resources, the influence of the solid-liquid rate, the amount of phosphoric acid catalyst, the liquefaction temperature and the liquefaction time on the liquefaction products of wood packaging waste were studied in this paper. The results indicate that the liquefaction residue rate rapidly decreases at first and then slowly goes down to the minimum at 170°C; along with the catalyst content's raise, the residu rate is on the decline which is more evident when the catalyst content drops from 3% to 7%; when the solid-liquid is less than 1: 5, the residue rate drops significantly; and the increase of the reaction time can greatly affect the liquefaction residue rate, especially when the liquefaction temperature is 150°C, the solid-liquid rate is 1:4, the amount of catalyst is 7%, and the reaction time is 4h, the residue rate can reach 6.04% which is the minimum.

Obtaining needle coke from coal liquefaction residue

Chromatography/mass spectrometry (GS/MS) was used to study toluene-soluble (TS) and pyridine-soluble (PS) fractions obtained from coal liquefaction residue by solvent extraction. It was found that the toluene-soluble fraction, containing mainly polycyclic aromatic hydrocarbons with 2-4 rings, is a good feedstock for making needle coke. The pyridine-soluble fraction cannot be used for these purposes because it contains more aromatic hydrocarbons with 5 or more rings. The composition of the studied samples determines their different behavior in carbonization (coking).

Preparation of mesoporous activated carbons from coal liquefaction residue for methane decomposition

Mesoporous activated carbons were prepared from direct coal liquefaction residue (CLR) by KOH activation method, and the experiments were carried out to investigate the effects of KOH/CLR ratio, solvent for mixing the CLR and KOH, and carbonization procedure on the resultant carbon texture and catalytic activity for catalytic methane decomposition (CMD). The results showed that optimal KOH/CLR ratio of 2: 1; solvent with higher solubility to KOH or the CLR, and an appropriate carbonization procedure are conductive to improving the carbon pore structure and catalytic activity for CMD. The resultant mesoporous carbons show higher and more stable activity than microporous carbons. Additionally, the relationship between the carbon textural properties and the catalytic activity for CMD was also discussed.

Research on Pyrolysis Kinetics of Shenhua Coal and Direct Liquefaction Residue

The pyrolysis tests of Shenhua coal and Shenhua direct liquefaction residue have been carried out using thermogravimetric at the differential heating rate. The kinetic parameters k and E were calculated using DAEM method. Results show DAME model can describe the pyrolysis behavior of Shenhua coal within the range of 20% to 95%, the activation energy of coal pyrolysis ranges from 53.98 to 279.38 kJ/mol, and DAME model can describe the behavior of Shenhua direct liquefaction residue within the range of 10% to 80%, the activation energy of residue pyrolysis is about 170 kJ/mol. The results of which are basically consistent with the experimental data.

Preparation and applications of hierarchical porous carbons from direct coal liquefaction residue

Hierarchical porous carbons (HPCs) were prepared from direct coal liquefaction residue (CLR) by KOH activation with addition of silica or silicate. Based on the template role of the mineral salts formed during the KOH activation process, the obtained HPCs have both mesopores and micropores. Several series of samples with different preparation conditions, such as different silica sources, additive dosages, washing procedures after carbonization and additional KOH for the additive in the activation process, were prepared and characterized. The results show that the microporosity of the carbons can increase by more than 28% owing to the addition of silica or silicate, along with the ratio of mesoporosity to microporosity being close to 1:1. Compared with the CLR-based carbon from traditional KOH activation, HPCs with appropriate preparation conditions have improved catalytic performance for catalytic methane decomposition and higher capacitances for supercapacitors.

The Liquefaction Mechanism Research of Straw Fiber in Polyhydric Alcohol

Two key products were isolated and purified from liquid mixture composition of wheat straw, by means of a combination of organic solvent extraction and column chromatography. Their structures were identified on basis of nuclear magnetic resonance (1H-NMR, 13C-NMR, DEPT), mass spectrometry (MS), and infrared (IR). The mechanism of liquefaction of straw was inferred from the structures of products and changes of hydroxyl value and liquefaction residue, which make up the lack of mechanistic studies of overall utilization of plant fibers.

The Distribution of Gaseous Product during Pyrolysis of Direction Liquefaction Residue and Coal

The pyrolysis of Shenhua direction residue and Shenhua coal was investigated in a thermo gravimetric analyzer. The TG and DTG curve indicated that compared with coal, the residue has higher weight loss and weight loss rate due to the higher content of heavy oil and asphaltene which produced during the liquefaction process; The residue and coal were also investigated in a fixed bed reactor to determine the composition and the yield of the gaseous product evolved. The main gases were H2, CH4, CO, CO2, C2H4 and C2H6, the residue has less gas produced because most of the active component in coal was destroyed during the liquefaction process, so the main component in residue is inactive substances. The maximum evolution temperature of CO, CO2, C2H4 and C2H6 was about 500°C, which were related to the maximum weight loss rate temperature, in this temperature the decomposition rate of the coal macromolecular structure is largest.

Protic ionic liquids extract asphaltenes from direct coal liquefaction residue at room temperature

Asphaltenes in direct coal liquefaction residue (DCLR) are highly aromatic and polydisperse mixtures, which are important precursors for producing high value-added carbon materials. In this research, a series of protic ionic liquids (PILs) with organic carboxylate anions were synthesized and applied to extract asphaltenes from DCLR at room temperature. The extracts were characterized by elemental analysis, FTIR, 13C-NMR, quinoline insolubles tests and so on. The results show that asphaltenes with the potential of precursors of carbon materials can be separated from DCLR at room temperature using PILs and the solid–liquid separation is carried out facilely due to the lower viscosities of PILs. The influences of PILs structures on extraction yields and atomic ratios of H/C were also investigated. As alkyl chain length of PILs anions increases, extraction yields of asphaltenes increase while H/C ratios decrease. Moreover, extraction yields vary with various cations of PILs and increase according to the order of N-methylimidazolium ([MIM]+)<triethylammonium ([TEtA]+)<3-methylpyridinium ([MPy]+), but H/C ratios decrease following the order of N-methylimidazolium ([MIM]+)>triethylammonium ([TEtA]+)>3-methylpyridinium ( [MPy]+). The asphaltenes extracted from DCLR with PILs have the excellent properties for preparing carbon materials, such as lower H/C ratios, higher aromaticities, lower sulfur contents and nearly no quinoline insolubles.

Effect of Pinus radiata Bark Polyphenols on Phenol Liquefaction of Cellulose in the Presence of p-Toluene Sulfonic Acid Catalyst

Abstract The influence of Pinus radiata bark polyphenol components in the phenol liquefaction of P. radiata bark was investigated using p-toluene sulfonic acid (PTSA) and sulfuric acid (SA) as acid catalysts. A series of the phenol liquefaction reactions were carried out using mixtures of pure cellulose with increasing amounts of hot-water extract (HWE) of P. radiata bark—the polyphenol-rich component of bark. The yields of liquefied product reactions and combined phenol amounts in them were determined, and the liquefaction residues were also analyzed for determination of acid-soluble and insoluble polyphenols and residual cellulose fractions. The yield of cellulose liquefaction decreased linearly with increasing amounts of HWE with the effect being more pronounced for SA than for PTSA. The combined phenol amount increased with liquefaction yield increases for both SA and PTSA catalysts, but at liquefaction yield levels above 83 percent, more phenol was combined for SA catalyst than for PTSA catalyst. The liquefaction residues contained lower cellulose and higher polyphenol components for SA catalyst than for PTSA catalyst at the same liquefaction time. The results indicate that the bark polyphenol components can significantly interfere in the acid-catalyzed bark phenol liquefaction reactions by their excessive condensation with cellulose and/or phenol, especially in the presence of SA catalyst.

Application of Iron-Containing Magnetic Ionic Liquids in Extraction Process of Coal Direct Liquefaction Residues

Three kinds of iron-containing magnetic ionic liquids (ILs), including imidazole-based, pyridine-based, and pyrrolidine-based ILs, were synthesized respectively, and were used to dissolve coal direct liquefaction residues (CDLR) to obtain asphaltene fractions under the conditions of given time, temperature, and mass ratio of ILs to CDLR. The extracts from CDLR were characterized by ultimate analysis, proximate analysis, FT-IR, and 13C NMR. The results show that physicochemical properties of the extracts obtained with different magnetic ILs consisting of different cationic rings are different, and pyridine-based magnetic IL is an effective extractant to extract asphaltenes from CDLR among the three magnetic ILs. The extracts might be good precursors for preparing high-value-added carbon materials because of their higher carbon content, lower H/C, and ash content.