Coal Liquefaction Products Research Articles

Estimation of Fuel Properties for the Heavy Fraction of Biomass Pyrolysis Oil Consisting of Proposed Structures for Pyrolytic Lignin and Humins

The organic component of biomass pyrolysis oils is composed of a light fraction (C2–C4 volatiles, sugar- and lignin-derived monomers) and a less polar heavy fraction (pyrolytic lignin/humins, greater than approximately 200 g/mol). Importantly, this heavy fraction can account for roughly one-third to one-half of the total pyrolysis oil. While the composition and characteristics of the light fraction are generally well understood, research is still needed for the characterization of the heavy fraction. Some important thermodynamic fuel properties of this fraction are the heat of combustion, normal boiling point, heat of vaporization, and flash point, which are (computationally) estimated in this work with regularized regression and empirical correlations. The quantification of these properties has implications on downstream utilization, particularly in the context of co-processing bio-oils with plastic and coal liquefaction products and/or crude petroleum. Finally, challenges and opportunities for (experimental) work are discussed for the advancement of sustainable valorization of biomass pyrolysis oils.

Molecular composition of direct coal liquefaction products obtained from the Shenhua industrial plant

The China Shenhua company has built and operated the only large industrial direct coal liquefaction (DCL) plant in the world for 15 years, with an oil product capacity of one million tons per year. However, there is insufficient information on the chemical composition of its products. In this study, the liquefaction product, including the distillate oil and the vacuum residue, as well as the circulating solvent were characterized by gas chromatography – mass spectrometry (GC–MS) and high-resolution mass spectrometry. The liquefaction oil has lower H/C ratio and higher oxygen and nitrogen contents compared to hydrogenation products derived from petroleum. The major component of the liquefaction oil is middle-temperature distillate, which is approximately 70 wt% concentrated in the range of 200–350 °C. Pyrene and perhydropyrene are the most abundant compounds in the liquefaction oil. Hydrocarbons with 1–4 aromatic rings were detected in the liquefaction oil, with skeletons of benzene, biphenyl, naphthalene, fluorene, phenanthrene, pyrene, etc.. Various partially hydrogenated and perhydrogenated aromatic compounds were identified in the oils and they even constitute the major component of the circulating solvent. 2,3-Dihydro-1H-phenalene was also found in high-relative abundance in the oils and has potential to be used as a marker for coal liquefaction produced through hydrogenation processes. Partially hydrogenated polycyclic aromatics exhibit higher dehydrogenation activity compared to tetralin. The organic component in the vacuum residue account for around 60 wt%, with toluene insoluble matter accounting for more than one third. The toluene soluble fraction has an H/C ratio of 0.82 and is mainly composed of aromatic with 4–8 rings. The molecular size and condensation degree of the residue are much higher than those of other fossil fuel-derived aromatic-rich substances. Further studies are necessary to evaluate whether aromatic hydrocarbons with such a high condensation degree are suitable for producing high-performance carbon materials.

Low-Calorie Coal Liquefaction Products as an Alternative Fuel Oil

Liquefaction of low-rank coal has been done to optimize the utilization of low-rank coal, which is less economical for obtaining alternative fuel oil. Coal samples were taken from the Bukit Pinang coal mine, Samarinda Ulu, East Kalimantan. Coal was liquefied using the NEDOL procedure at PUSPITEK, Serpong, South Tangerang, Indonesia. This Bukit Pinang coal liquefaction produces five fractions consisting of Naphta, Light Oil (LO), Middle Oil (MO), Heavy Oil (HO), and Coal Liquid Bottom (CLB) fractions. The liquefaction yield was dominated by the HO and CLB fractions (> 50% by weight). The naphtha, MO and LO fractions were fractionated using SiO2 GF254 Thin Layer Chromatography (TLC) plate. It produced aliphatic and aromatic hydrocarbon fractions. Aliphatic hydrocarbon fractions were analyzed using a Gas Chromatography-Mass Spectrometer (GC-MS), while the aromatic hydrocarbon fractions were not analyzed. Mass spectrum studies showed that the components consisted of n-alkanes, isoalkanes (branched alkanes), cycloalkanes and alkyl cycloalkanes. The aliphatic hydrocarbon components resulting from the liquefaction of low-rank coal showed its equivalence with the components that make up fuel oil. Therefore, this coal liquefaction can be suggested as an optimization for low-rank coal, which is less economical.

Study on Oxygen Speciation in the Products of Direct Coal Liquefaction and Co-Liquefaction of Coal and Petroleum Residues

Study on Oxygen Speciation in the Products of Direct Coal Liquefaction and Co-Liquefaction of Coal and Petroleum Residues

Coal and waste direct liquefaction, using glycerol, polyethylene waste and waste tyres pyrolysis oil. Optimisation of liquids yield by response surface methodology

Coal and waste direct liquefaction was carried out to decrease the hydrocarbons production negative bearing to environment. The wastes studied were glycerol, polyethylene waste and waste tyres pyrolysis oil. Glycerol and waste tyres pyrolysis oil were blended with tetralin and used as solvent for coal direct liquefaction (T = 350–450 °C; N2; waste:tetralin at different weight ratios). Glycerol may be considered as a waste from the production of fatty acid methyl esters (FAME). Waste tyres pyrolysis oil showed to be a good hydrogen donor solvent. Solid polyethylene wastes were mixed with coal and used in coal co-liquefaction tests, which showed to be a good option to produce liquid hydrocarbons for fuels or raw materials for chemical industry. Although liquids yield using waste tyres pyrolysis oil or glycerol were high, respectively 62% wt. and 51% wt., the use of polyethylene allowed increasing them to 80% wt. Different experimental conditions were studied, namely: experimental temperature, run time, solvent type and composition and hydrogen initial pressure. The effect of commercial catalysts on co-liquefaction was also studied and the results obtained were compared with those obtained with coal impregnated with Fe or Mo (1% wt./coal). Response surface methodology (RSM) was used to predict the influence of the main experimental conditions studied on product yields. This methodology resulted to be a good one to predict coal liquefaction and co-liquefaction products yields, as predicted values were similar to experimental data. In addition, RSM approach led to the selection of tetralin as solvent and to the use of coal impregnated with 1% of Mo, as liquids yield increased up to 96% wt.

Combustion of synthetic jet fuels: Naphthenic cut and blend with a gas-to-liquid (GtL) jet fuel

There is increasing interest for utilizing synthetic biofuels in blends with conventional oil-derived liquid fuels. In this contest, research on the combustion of synthetic jet fuels has lately gained significance because they could help addressing sustainability and security of supply for air transportation. Improving the kinetic modeling of the oxidation of synthetic fuels requires further investigations under well-controlled conditions. The combustion of a 100% naphthenic cut fitting typical chemical composition of biomass or coal liquefaction products and a 50%vol. mixture with Gas to Liquid fuel were studied in a jet-stirred reactor (JSR) under the same conditions (550–1150K, 10bar, equivalence ratio of 0.5, 1, and 2, and 1000ppm of fuel). For simulating the kinetics of oxidation of these fuels, model-fuels were designed to fit fuels chemical composition and properties. They consisted of mixtures of n-decane, 2-methylheptane, 3-methylheptane, n-propylcyclohexane, decahydronaphtalene, and tetrahydronaphtalene. The proposed detailed chemical kinetic reaction scheme was validated using the whole experimental data set acquired in the present work; for the oxidation of pure GtL, we used previous obtained data. For interpreting the results, reaction pathways and sensitivity analyses were used.

Preparation of Carbon Micro-Spheres from Liquefaction Products of Lignite with NaOH-Methanol

Carbon micro-spheres (CMSs) with diameters of several micrometers were synthesized by surfactant-assisted self-assembly of direct coal liquefaction products, which come from the lignite liquefaction with NaOH and methanol. The synthesized CMSs were characterized by X-ray diffraction, scanning electron microscope and TG analysis. The results show that cetyltrimethylammonium bromide (CTAB) and carbonization temperature play an important role in the formation of CMSs. The CMSs have a spherical morphology, smooth surface, probable size of about 5-10μm and a relatively high thermal resistance in N2 atmosphere. The formation mechanism of these CMSs was discussed based on the feature of the reaction system.

A novel analytical approach for oxygen speciation in coal-derived liquids

Since the production of crude oil may not meet the increasing demand in the next future, coal liquefaction products have sparked great interest as one of the possible substitutes of petroleum in the transportation field. Speciation of oxygen in direct coal liquefaction products is essential considering the important role of oxygenated compounds in coal conversion reactions. This study attempts to characterize them as fully as possible. The originality of this approach is based on the development of complementary analytical tools to describe the composition of two coal-derived distillates: a naphtha cut and a gasoil cut.Two-dimensional gas chromatography (GC×GC), high resolution mass spectrometry (FT-ICR/MS), nuclear magnetic resonance (NMR), and UV–visible spectroscopy were applied to these two matrices. This analytical scheme shows that among 2.89%w/w of elemental oxygen present in the naphtha cut, 1.78%w/w O corresponds to phenols, 0.08%w/w O to alcohols and 0.21%w/w O to ketones. Concerning carboxylic acids, they are negligible (<0.01%w/w). Thus, a total of 2.07%w/w O is quantified what represents 72% of the oxygenated compounds contained in the naphtha cut. Similarly, in the gasoil cut, among the 0.80%w/w O of elemental oxygen, 0.62%w/w O are attributed to phenols, 0.07%w/w O to alcohols, and 0.015%w/w O to ketones. Benzo and dibenzofurans may represent the species which have not been quantified.Quantification of alcohols and phenols by carbon atom number is also allowed by GC×GC–FID using response factors. It shows that the carbon atom number varies from 6 to 11 for phenols and from 4 to 9 for alcohols. Similarly, carboxylic acids distribution by alkylation degree can be obtained by combining FT-ICR/MS and NMR results. This unique multi-technical approach offers a detail level which was never reached so far in terms of oxygenated compounds characterization for such products. This information is crucial to evaluate the potential of these liquids as a substitute for fuel and envisage their upgrading.

Diesel production in coal-based high-temperature Fischer–Tropsch plants using fixed bed dry bottom gasification technology

Gas-to-liquids (GTL) and also coal-to-liquids (CTL) Fischer–Tropsch plants using high-temperature (entrained flow) gasification all face the same refining challenge, which is meeting the EN590 density specifications of 820kgm−3 at 15°C for the produced distillate. Fischer–Tropsch distillates can, however, be blended with high density distillates originating from sources such as crude oil, direct coal liquefaction or coal pyrolysis products, in an effort to conform to those diesel density requirements. Fixed bed dry bottom (FBDB) gasification technology can in combination with high-temperature Fischer–Tropsch (HTFT) synthesis provide a way to produce final on-specification CTL transportation fuels. Hydroprocessing FBDB gasification tar results in a distillate with high density whereas a hydrotreated HTFT distillate corresponds to a highly paraffinic product with high cetane number but low density. Both distillates can be blended to produce a market-ready final diesel which is of particular industrial importance for CTL applications in countries which have no oil but low-rank coals instead and viable options for carbon capture and storage (CCS).

Investigating comprehensive two-dimensional gas chromatography conditions to optimize the separation of oxygenated compounds in a direct coal liquefaction middle distillate

Considering the global energetic context, diversifying fuels is of growing importance and many new alternatives are promising. Coal liquefaction products definitely appear among the new generation substitutes. These product's characteristics are very far from fuel specifications as they are mainly composed of naphthenes, aromatics, polycondensed naphthenic and aromatic structures and heteroatomic compounds (nitrogen and oxygen), with a very low paraffin content. Identification and quantification of oxygen-containing species in coal-derived liquids are of considerable importance to understand their behaviors in further processing. However, these species have not been characterized as fully as the predominant hydrocarbon components. Literature shows that these compounds consist mainly in alkylated phenolic and furanic structures. Therefore, comprehensive two-dimensional gas chromatography has been investigated to provide enhanced molecular characterization of these complex samples. Several different configurations involving innovative column configurations were tested. Each of them was optimized by testing different column lengths, modulation periods, and oven conditions. A comparison of the contribution of each column configuration was carried out regarding four main criteria: individual separation of oxygenates, group type separation, resolution, and space occupation. One of them enabled an outstanding separation of paraffins, naphthenes, monoaromatics, diaromatics and targeted O-compounds in a direct coal liquefaction product. It was therefore subjected to further experimentations using a time-of-flight mass spectrometer to validate the identification and unravel more than fifty oxygenated molecular structures. A group-type quantification was also established for four column arrangements and gives the distribution of paraffins, naphthenes and aromatics. It can be concluded from this study that a non-orthogonal arrangement involving a highly polar column in the first dimension was the most adapted one.

Characterization of Oxygenated Species in Coal Liquefaction Products: An Overview

Identification and quantification of oxygen-containing compounds in coal-derived liquids is of considerable importance to understand their behaviors in further processing. However these species have not been characterized as fully as the predominant hydrocarbon components. This paper surveys the analytical tools investigated for the separation, selective identification, and quantification of oxygenated compounds in coal oils. Although liquid and gas chromatography emerge as the most widespread techniques, many other spectroscopic techniques like Fourier transform infrared spectroscopy (FTIR), NMR, and mass spectrometry enabled one to improve the understanding of these species. The state-of-the-art of preparative fractionation is also presented. Furthermore, the advantages and limitations of each technique are discussed, and the contribution of multicoupled chromatographic systems to this type of analysis is highlighted.

Kinetics of Shenhua coal liquefaction catalyzed by [formula omitted]/ZrO 2 solid acid

Based on the structural inhomogeneities of coal and intermediate products of coal liquefaction, a new kinetic model was advanced to simulate the Shenhua coal liquefaction catalyzed by SO 4 2 = /ZrO 2 solid acid catalyst using kinetic lump method. It was found that coal was hydrocracked to preasphaltene, asphaltene, oil and gas directly, and preasphaltene and asphaltene were further hydrocracked into oil and gas products in coal liquefaction. Certain regressive reactions existed in the process. The liquefaction conversions calculated from the model agreed well with the experimental data for Shenhua coal liquefaction catalyzed by SO 4 2 = /ZrO 2 solid acid at the range of experimental conditions, and the activation energies were 69–136 kJ mol −1. There existed obvious regressive reactions at higher liquefaction temperatures. However, besides the regressive transformation of oil and gas to asphaltene at 450 °C liquefaction, there also existed condensation processes of preasphaltene and asphaltene to coke.

06/01116 ESI FT-ICR mass spectral analysis of coal liquefaction products: Wu, Z. et al. Fuel, 2005, 84, (14–15), 1790–1797

06/01116 ESI FT-ICR mass spectral analysis of coal liquefaction products: Wu, Z. et al. Fuel, 2005, 84, (14–15), 1790–1797

The Characterization of Coal Liquefaction Products Obtained under an Inert Atmosphere and Catalytic Conditions. Part II: Soluble Products

Beypazari and Tunçbilek lignite were liquefied using two different catalyst methods—physically mixing and impregnation. The liquefaction occurred under conditions of inert atmosphere and various process parameters. Solvent to coal ratio, pressure, catalyst type, catalyst concentration, temperature, and time were examined as process parameters. The most appropriate parameters for the total soluble products obtained by liquefaction of both lignites and for elemental analysis of preasphaltenes were determined as follows: 2/1 solvent to coal ratio; from 1.25 MPa to 2.50 MPa initial nitrogen pressure; Fe 2 O 3 and Mo(CO) 6 as catalyst types; 3% as catalyst concentration; 400°C as reaction temperature; and 60 min as reaction time. In general, fuel quality of both preasphaltene and total soluble products decreased as temperature increased above 400°C and reaction time exceeded 60 min. The fuel quality of the preasphaltenes and the total soluble products obtained under the catalytic conditions and in the state of impregnation of catalyst onto coal is higher than under the noncatalytic conditions and in the state of physically mixing of catalyst.

The Characterization of Coal Liquefaction Products Obtained under Inert Atmosphere and Catalytic Conditions. Part I: Insoluble Products (Chars)

In this study, two types of Turkish lignite were liquefied under inert atmosphere and catalytic conditions. Catalyst was added to the reaction medium by physically mixing or impregnation. The products obtained at coal liquefaction were separated into two groups as soluble products with THF extraction and insoluble products (chars). The effects of various process parameters on the properties of chars were examined. The ash contents of chars were decreased significantly by increasing solvent to coal ratio and reaction temperature, and changed partially by pressure, catalyst type and concentration. Carbon, hydrogen and nitrogen contents of the chars decreases, but the sulphur and oxygen contents increase with increasing solvent to coal ratio, pressure, catalyst concentration, reaction time and reaction temperature. The fuel quality of chars obtained by catalyst impregnation method was determined to be much higher with respect to the catalyst physically mixing method.

ESI FT-ICR mass spectral analysis of coal liquefaction products

We have applied electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to analyze the pyridine soluble fraction of a distillation resid and a further processed liquid product in a coal liquefaction process. The inherent high resolving power ( m/Δ m 50%>300,000, in which Δ m 50% is full mass spectral peak width at half-maximum peak height) and mass accuracy (<1 ppm) of FT-ICR MS makes it possible to resolve and identify polar heteroatomic species. The resid contains more heteroatomic compounds and a higher molecular weight distribution whereas the liquid sample is lower in average mass and more saturated. The data confirms that the liquefaction process produces lower mass, hydrogenated liquid product whereas the resid (highly aromatic and of high heteroatom content) must be recycled to reduce its heteroatom content and increase its degree of saturation.

04/00679 Study on quick liquefaction reaction of coal: Lin, K. et al. Ranliao Huaxue Xuebao, 2003, 31, (1), 49–52. (In Chinese)

The reaction process of quickly liquefying Chinese Yangcun bituminous coal was studied under pressure of hydrogen 70?MPa(cold) by using resonance agitation reactor The results show that a high coal conversion has been obtained at short reaction time (coal quick liquefaction) by raising reaction temperature appropriately and enhancing active hydrogen concentration and improving its transfer speed and path in the reaction system The best reaction temperature of coal quick liquefaction (CQL) is the upper limit of the coal pyrolysis temperature range in TGA Compared coal conversion and benzene soluble (BS) yield of CQL with those of common liquefaction,CQL greatly enhances efficiency of coal liquefaction and it is favorable for further utilizing coal liquefaction product

Use of Short Chained Alkylphenols (SCAP) in Analysis of Transport Behaviour of Oil Contaminated Groundwater

Shortchained alkylphenols (SCAP) represent a main constituent of crude oil and coal liquefaction products. Due to their specific oil/water partitioning behaviour and high aqueous solubility they can be detected in oil exploitation waters and groundwaters affected by various spills near oil pipelines, oil exploitation sites and coal liquefaction plants. New efficient and powerful analytical techniques have been developed that allow the identification of all 34 individual compounds (C0-C3) without derivatisation and in complex matrices. Due to the different physico-chemical properties of the SCAP, differential transport behaviour in groundwater can be observed, changing the relative concentrations of SCAP downgradient in space and time. These characteristic ratios can be employed to derive information on migration direction and the ageing of the source of contamination. A case study is presented to illustrate the use of this new tool.

Study for development of the coal liquefaction process by 150 tons/day pilot plant. (II). Coal liquefaction products of NEDOL process

Study for development of the coal liquefaction process by 150 tons/day pilot plant. (II). Coal liquefaction products of NEDOL process

00/02402 Study for development of the coal liquefaction process by 150 t/day coal liquefaction pilot plant. III. Properties of coal liquefaction products and their toxicological assessment

The effect of swelling untreated and SO2-treated Black Thunder coals on coal liquefaction behavior was investigated. Catalyst precursors including Molyvan L, molybdenum naphthenate, and nickel octoate were introduced into swelling solvents consisting of tetrahydrofuran (THF), isopropanol, or methanol at typical loadings of 700 ppm of active metal. Coal liquefaction reactions were performed at 385 and 410 °C using 1-methylnaphthalene, dihydroanthracene, or coal-derived V1074 as liquefaction solvents. The efficacy of the process was measured by using coal conversion to THF-soluble materials. Pyrene was added to the liquefaction feed to provide a measure of catalyst hydrogenation activity. Swelling of coal in the presence of a catalyst prior to liquefaction should increase the accessibility of the interstitial structure to the catalyst and, therefore, increase coal reactivity at liquefaction conditions; however, this concept was valid with only one catalyst system. Only the addition of molybdenum naphthenate with added excess sulfur resulted in improved conversion of Black Thunder (WY sub-bituminous) coal. No improvement with the addition of either Molyvan L or nickel octoate was observed. The addition of all of the catalyst precursors resulted in increased pyrene hydrogenation; therefore, there was not a direct correlation of hydrogenation and coal conversion catalytic activities.