COAL LIQUEFACTION WITH ANTHRACENE OIL. INFLUENCE OF SOLVENT PRETREATMENT,TEMPERATURE, CATALYST AND PRESSURE

ABSTRACT

The effect of solvent pretreatment, temperature, a CoMo/Al₂O₃ catalyst and pressure on coal liquefaction with anthracene oil has been evaluated. The experiments were conducted in a 500 ml autoclave with 10 g of a Spanish subbituminous A coal. 30 g of solvent, 1 hour reaction time and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The behaviour of anthracene oil as coal liquefaction solvent is very much enhanced by prehydrogenating it and by the addition ot an active catalyst. The influence of temperature depends on the operating conditions such as solvent pretreatment, catalyst, pressure etc. The addition of an active catalyst greatly improves conversion and the quality of the liquefaction products and diminishes repotimerization reactions. Hydrogen pressure is essential for coal liquefaction with anthracene oil, although over 16 MPa no further increase in coal conversion is observed.     

COAL LIQUEFACTION WITH ANTHRACENE OIL. INFLUENCE OF SOLVENT PRETREATMENT, TEMPERATURE, CATALYST AND PRESSURE

The effect of solvent pretreatment, temperature, a CoMo/Al₂O₃ catalyst and pressure on coal liquefaction with anthracene oil has been evaluated. The experiments were conducted in a 500 ml autoclave with 10 g of a Spanish subbituminous A coal. 30 g of solvent, 1 hour reaction time and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The behaviour of anthracene oil as coal liquefaction solvent is very much enhanced by prehydrogenating it and by the addition ot an active catalyst. The influence of temperature depends on the operating conditions such as solvent pretreatment, catalyst, pressure etc. The addition of an active catalyst greatly improves conversion and the quality of the liquefaction products and diminishes repotimerization reactions. Hydrogen pressure is essential for coal liquefaction with anthracene oil, although over 16 MPa no further increase in coal conversion is observed.     

THIN-LAYER CHROMATOGRAPHY AS AN ALTERNATIVE TO SARA ANALYSIS OF COAL DERIVED LIQUIDS

ABSTRACT

SARA analysis has been applied to various coal derived liquids. Due to its tediousness, alternative procedures have been sought, capable of accomodating large numbers of samples. Procedures have been developed for separating toluene extracts into asphaltenes and oils and of pyridine extracts into preasphaltenes, asphaltenes and oils. In spite of a number of problems connected with absolute method calibration and with finding separation conditions giving similar results as solvent precipitation, thin layer chromatography with flame ionization detector (TLC/FID) has been shown to be a sensitive indicator of compositional changes of coal derived liquids as they depend on changes of experimental conditions of the liquefaction experiment.     

DIRECT HYDROGENATION OF A SPANISH LOW RANK COAL. THE EFFECT OF PROCESS VARIABLES

ABSTRACT

The effect of operating conditions on the liquefaction behaviour of a Spanish lignite was studied using a 250 ml stirred autoclave, and the following operating conditions (except otherwise specified): 400 °C, 1 hour, 3.5 MPa initial (cold) H₂ pressure, 400 rpm and 40 g/10 g tetralin/coal charge. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue using pentane, toluene and THF as extractive solvents

The influence of temperature was explored in the 300–475 °C range, observing little further improvement in liquefaction yields over 400 °C, and retrogressive reactions over 450 °C. The effect of time was studied from 0 to 180 minutes and was concluded that 1 hour is an appropriate period for liquefying a black lignite, since there is little further conversion for longer times. The influence of pressure and gas type was studied using 0, 3.5 and 7.0 MPa initial (cold) pressure of H₂ and of N₂, and the effect of stirring using 0 and 400 rpm. Little influence of these variables was observed, which is attributed to the strong H-donor solvent, high solvent/coal ratio and long reaction time used.     

LIQUEFACTION OF BEYPAZARI LIGNITE USING NiCl2-KCl-LiCl CATALYSTS. 1. DIFFERENCE IN SOLID AND MOLTEN SALT CATALYSIS

ABSTRACT

Liquefaction of Beypazan lignite in tetralin using NiCl₂-KCl-LiCl (14:36:50 molar percentages) as catalyst was investigated. Effects of the catalyst/lignite ratio and temperature were determined in experiments done at 275°C, 300°C and 360°C. Liquid products were separated into oils, asphaltenes and asphaltols by a solvent extraction method. Yield of liquefaction increased with temperature in all experiments, the highest yield was observed in experiments performed at the eutectic temperature of the catalyst mixture. The highest yields of oils were 20% and 30% with a catalyst/coal ratio of 0.5 at 275°C and 300°C, respectively. The activity of the catalyst increased in experiments in which the catalyst was molten. The yield of asphaltenes were not affected with increases in the catalyst/coal ratio in the experiments done at 275°C or 300°C in which the catalyst mixtures were in solid state. Asphaltene yields decreased from 25% to less than 5% with increasing values of catalyst/coal ratio and the asphaltol yields remained constant at 10% between catalyst/coal ratios of 0.25 and 1.00 and suddenly increased to 30% and 40% for catalyst/coal ratios of 1.50 and 2.00, respectively, at 360°C. The molecular weights of the oils decreased from 340 to a minimum value of 245 as the catalyst/coal ratio was increased from 0 to 1.00 in experiments done at 360°C where the catalyst was molten. As the catalyst/coal ratio was further increased from 1.00 to 2.00 the molecular weight increased to 310.It seemed that the N1Cl₂-KCl-LiCl catalyst mixture in all catalyst/coal ratios was more efficient in molten phase than it was used as a solid mixture.     

EFFECT OF IRON CATALYST ON THE COMPOSITION OF OIL FROM COAL LIQUEFACTION

ABSTRACT

The effect of two iron catalysts, red mud and CGS S-G, as well as C0-Mo/AI₂O3 and Ni-Mo/Al₂03 commercial catalysts on the composition of oil derived from the liquefaction of Japanese subbituminous coal have been investigated comparatively by conventional autoclave experiments at 440 and 450^°C under initial hydrogen pressure of 85kg/cm² G with tetralin to coal weight ratio of 3. From the results obtained at 450^°C, total conversion and the yield of gas revealed almost same level with four catalysts, but the oil product from molybdenum catalysts showed higher yield than that from iron catalysts. CGS S-G catalyst also showed higher yield of oil product than red mud catalyst. Reaction behavior of two iron catalysts were also tested by solvent recycle mode experiments.     

THIN-LAYER CHROMATOGRAPHY AS AN ALTERNATIVE TO SARA ANALYSIS OF COAL DERIVED LIQUIDS

SARA analysis has been applied to various coal derived liquids. Due to its tediousness, alternative procedures have been sought, capable of accomodating large numbers of samples. Procedures have been developed for separating toluene extracts into asphaltenes and oils and of pyridine extracts into preasphaltenes, asphaltenes and oils. In spite of a number of problems connected with absolute method calibration and with finding separation conditions giving similar results as solvent precipitation, thin layer chromatography with flame ionization detector (TLC/FID) has been shown to be a sensitive indicator of compositional changes of coal derived liquids as they depend on changes of experimental conditions of the liquefaction experiment.     

DISSOLUTION OF COALS NEAR CRITICAL CONDITIONS

ABSTRACT

Two lignites and one bituminous coal were extracted with benzene, toluene and pyridine at both sub and overcritical conditions in a specially designed experimental system which enabled easy solid-liquid separation. Extract yields increased somewhat at overcritical conditions due to more thermal decomposition. The differences between the power of the solvents were not apparent for the lignites, whereas the solubility in pyridine of the bituminous coal was very much higher than those in benzene and toluene. The amounts of oils, asphaltenes and preasphaltenes in the extracts depended on the type of coal and the solvent.     

IRON COMPOUNDS AND C0-Mo/Al2O3 CATALYSTS: ACTIVITY IN DIRECT HYDROGENATION OF A SUBBITUMINOUS A COAL WITH AN H-DONOR SOLVENT

Abstract

The effectiveness of different catalysts were compared in coal liquefaction experiments using a 250 ml stirred autoclave, 10 g of a Spanish Subbituminous A coal, 1 hour reaction time, 17 MPa operating pressure, 400 rpm stirring speed, at 425 and 450 °C with 2/1 and 3/1 tetralin/coal ratio. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue using pentane, toluene and THF as extractive solvents. Three iron-oxide containing catalysts: red mud, an Fe2O3 aerosol and Cottrell ash (by-product of the aluminium industry); and three alumina supported catalysts: CMA, which is a conventional CoMo/Al2O3 catalyst, CZMA which in addition contains Zn as a second promoter, and CZMFA which has the alumina acidified with fluorine and also contains Zn, were compared. It has been reported that the addition of Zn and of F enhances the HDS, cracking, hydrocracking or hydrogenating activities of CoMo/Al2O3 catalysts in experiments with pure compounds. The objective of this study was to determine if the addition of Zn and of F has also a beneficial effect in the catalyst activities in coal liquefaction, and also to compare cheap iron containing catalysts with the more sophisticated and expensive alumina supported ones.

The results showed that 1) Catalysts effects depend on the operating conditions used, and that with tetralin, a strong H-donor solvent, they never are very pronounced. 2) The supported catalysts have higher activities in coal liquefaction than the iron ones, but there are no significant differences among the catalysts within each group. 3) Zn, which is a cheaper metal than Co, can substitute succesfully for half the amount of Co and retain the activity of the CoMo/Al2O3 catalyst in coal liquefaction. 4) The addition of F to the CoMo/Al2O3 catalyst does not show a benefecial effect     

ELEMENTAL COMPOSITION OF ASPHALTENES FROM COAL LIQUEFACTION

The elemental composition (C, H, N, S, O) of asphaltenes isolated from coal liquefaction experiments carried out at different temperatures and tetralin/coal ratios has been determined. The liquefaction experiments were conducted in a 250 ml autoclave, with 10 g of a Spanish subbituminous A coal, for 1 hour, and at 17 ± 1 MPa operating pressure and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The % S and % O are lower in asphaltenes than in coal, while the % C and % N are higher and % H depends on the temperature and tetralin/coal ratio used. On the other hand asphaltenes % C decreases, and % H and % O increase as the tetralin/coal ratio is raised at every temperature except 475 °C, while % S and % N do not have a clear variation.     

RECOVERY OF ASPHALTENES FROM TAR SAND BY SUPERCRITICAL FLUID EXTRACTION

ABSTRACT

Many non-oil producing countries are enriched with other sources of energy, for example tar sand, oil shale, coal, biomass, and uranium, that are not fully utilized. Supercritical fluid extraction (SFE) of tar sand was carried out in a batch autoclave at different temperatures. Extracts recovered from SFE were fractionated into oils, asphaltenes, preasphaltenes and gases by solvent extraction. The highest yield) of SFE (24.3 wt % dry basis) from tar sand was obtained with n-pentane/benzene (1/1, v/v’) mixture at 655 K. Comparison of the amount of n-alkanes (C1–C4) evolved at 585 K and 685 K shows that the amount of methane is significantly increased at 685 K whereas the amount of C4 alkane is reduced. At 685 K, hydrogen and methane represent 45·1 vol % of the gases evolved from the SFE. The yields of C1–C3 alkane hydrocarbons were higher for supercritical fluid extracts at 685 K as compared to those obtained at 585 K. The quantity of olefines (C₂H₄ + C₃H₆) was found between 5·1 and 10·1 vol %.     

PRODUCTS FROM FLASH PYROLYSIS OF A TURKISH LIGNITE IN A FREE-FALL REACTOR UNDER VACUUM

ABSTRACT

Flash pyrolysis of a Turkish lignite under vacuum in a free-fall reactor was examined at a temperature range of 400 - 800 °C. Gaseous products were analysed with an on-line GC equipped with a manuel injection valve. Solvent fractionation was applied to the liquid product to separate preasphaltenes, asphaltenes and oils fractions. Two particle distributions of the lignite were used: ?0.315+0.2 mm and ?0.1 mm. The liquid yield increased with temperature up to 650 °C and, thereafter decreased for the larger particles. The maximum liquid yield, excluding pyroltic water, was found to be 8 % wt (dal) at 650 °C. In the case of the smaller particles the liquid yield increased steadily with temperature and the yield of liquid, excluding pyrolytic water, was 5.9 % wt (da) at 850 °C. The gaseous product yield also increased with temperature for both size fractions, and CO and CO₂ in the gaseous products were present in large amounts.     

TWO-DIMENSIONAL SOLUBILITY PARAMETER MAPPING OF HEAVY OILS

ABSTRACT

The solubility and insolubility of heavy oils and their fractions in dilute mixtures with various solvents were used to characterize heavy oil interactions. A two-dimensional solubility parameter, developed for the selection of solvents for organic polymers, was found to group all the solvents for each heavy oil fraction in polygon areas when the complexing solubility parameter component was plotted against the field force solubility parameter component. All fractions of Cold Lake vacuum residua, except for the saturate fraction, form concentric solubility areas. Therefore, in going in the direction of decreasing aromaticity from coke to asphaltenes to resins to aromatics, all solvents for the previous fraction in the series are also solvents for all subsequent fractions in the series. As a result, asphaltenes can be precipitated, but not extracted, from heavy oils. This is attributed to the interaction among polynuclear aromatics being the dominate interaction in petroleum that causes insolubility in hydrocarbon liquids. However, the paraffinic chains on the same petroleum molecules limit their solubility in highly complexing liquids. In contrast, even vacuum gas oils from the Exxon Donor Solvent coal liquefaction process are insoluble in aromatic liquids but soluble in moderately complexing liquids because of hydrogen bonding, resulting from oxygen functionality. Hydrotreating of these coal derived vacuum. gas oils reduces their oxygen functionality and increases their solubility areas so that they become compatible with petroleum liquids.     

PYROLYSIS AND LIQUEFACTION OF BRAZILIAN COAL AND COAL-DERIVED ASPHALTENES

ABSTRACT

The present work describes a study of the liquefaction and pyrolysis of a Southern Brazilian mineral coal and its derived asphaltenes, using conversion systems developed in our laboratory.

The results show that significant quantities of the intermediate polarity fraction named resins is obtained through the pyrolysis of coal, while after the liquefaction process higher quantities of the higher fractions was found. A model is proposed to explain the liquefaction and pyrolysis processes of both coal and coal-derived asphaltenes.     

HYDROLIQUEFACTION OF TEXAS LIGNITE IN COAL- AND PETROLEUM-DERIVED SLURRY OILS

ABSTRACT

Hydroliquefaction of Texas lignite (68.5%. C daf) was conducted in a batch autoclave under hydrogen in a coal–derived slurry oil at 90 bar initial pressure for temperatures of 380–460^° C and residence time of 15–60 minutes, or a vacuum distillate from petroleum at 435^° C for 60 minutes and initial H₂–pressure of 60–150 bar, or a vacuum residue from the same petroleum at 435 and 460^° C for 60 minutes and initial H₂–pressure of 90–150 bar or tetralin at 435^°C, 60 minutes and 90 bar initial H₂–pressure. Red mud plus sodium sulfide were added as a catalyst for all experiments. Lignite conversion ranged from 50 to 83%. The products were separated into gases, residue, asphaltenes, oils B,P. above 200^° C, oils B.P. below 200^° C. Total liquid products from coal reached 57% in coal-derived slurry-oil, 56% in vacuum distillate and 64% in vacuum residue at optimum conditions with 32% of product oil B.P. below 200^° C in vacuum distillate and 24% in vacuum residue. When coprocessing lignite with vacuum residue at 120 bar initial pressure, 435^°C and 60 minutes residence time the total mass balance presented an oil yield of 73%. with 32% boiling below 200^°C.     

HYDROCRACKING OF ARABIAN MIX ASPHALTENES IN THE PRESENCE OF MODIFIED RED MUD

ABSTRACT

Asphaltenes precipitated from an Arabian Mix vacuum residue were hydro-cracked in a batch autoclave at 435 and 460°C for 5-90 min. Experiments without catalyst, with modified red mud and with an industrial Co Mo/Al₂0₃ catalyst were compared. The products were fractionated into gas, naphtha, oil, asphaltenes and coke. Feed asphaltenes and several product fractions were characterised by elemental analysis, by average molecular mass and by ¹H n.mr. Due to the hydrogenation activity, both catalysts caused - with similar efficiency - the decrease of coke formation and the increase of quantity and quality of oil.     

KINETICS OF THERMAL LIQUEFACTION OF SEYITÖMER LIGNITE

ABSTRACT

Kinetics of non-catalytic liquefaction of Seyitomsr lignite has been investigated under hydrogen pressure, using tetralin as a Bolvent in a laboratory Bcale batch autoclave reactor.

In the first set of experiment hydrogen initial pressure and reaction temperature were kept constant, the reaction time and coal/aolvent ratio were changed at five and three levels espectively. In the second set of experiments coal/solvent ratio was kept constant and hydrogen initial pressure, reaction temperature and time were individually changed at four levels. The produot was analyzed in terms of total conversion, liquid yield and liquid product distribution determined as preasphaltenes, asphaltense and oila. A satisfactory correlation was obtained using the kinetic model proposed by Shalabi et al (1979).     

APPLICATION OF HIGH PERFORMANCE LIQUID CHROMATOGRAPHY FOR HYDROCARBON GROUP TYPE ANALYSIS OF CRUDE OILS

ABSTRACT

High performance liquid chromatography (HPLC) was applied to four commercial grade Saudi Arabian crude oils having API gravity in the range 28 to 38 for the determination of hydrocarbon group types namely asphaltenes, saturates, aromatics and polars. Each of these crude oils was separated into asphaltenes and maltenes using n-hexane as the precipitating solvent. The maltenes (n-hexane soluble) were fractionated into saturates, aromatics and polars fractions by n-hexane elution on a column packed with amino propylsilane chemically bonded to porous silica particles.

The data obtained shows that the weight percent saturates increase whereas aromatics, polars and asphaltenes decrease from Arab Heavy to Arab Bern through Arab Medium and Arab Light crude oil. The results obtained from HPLC were in comparison with those obtained from ASTM method D2007. This method is easier, faster and offer good repeatability. This method can be applied to other crude oils.     

LIQUEFACTION OF BEYPAZARI LIGNITE USING NiCl2-KCl-LiCl CATALYSTS. 1. DIFFERENCE IN SOLID AND MOLTEN SALT CATALYSIS

Liquefaction of Beypazan lignite in tetralin using NiCl₂-KCl-LiCl (14:36:50 molar percentages) as catalyst was investigated. Effects of the catalyst/lignite ratio and temperature were determined in experiments done at 275°C, 300°C and 360°C. Liquid products were separated into oils, asphaltenes and asphaltols by a solvent extraction method. Yield of liquefaction increased with temperature in all experiments, the highest yield was observed in experiments performed at the eutectic temperature of the catalyst mixture. The highest yields of oils were 20% and 30% with a catalyst/coal ratio of 0.5 at 275°C and 300°C, respectively. The activity of the catalyst increased in experiments in which the catalyst was molten. The yield of asphaltenes were not affected with increases in the catalyst/coal ratio in the experiments done at 275°C or 300°C in which the catalyst mixtures were in solid state. Asphaltene yields decreased from 25% to less than 5% with increasing values of catalyst/coal ratio and the asphaltol yields remained constant at 10% between catalyst/coal ratios of 0.25 and 1.00 and suddenly increased to 30% and 40% for catalyst/coal ratios of 1.50 and 2.00, respectively, at 360°C. The molecular weights of the oils decreased from 340 to a minimum value of 245 as the catalyst/coal ratio was increased from 0 to 1.00 in experiments done at 360°C where the catalyst was molten. As the catalyst/coal ratio was further increased from 1.00 to 2.00 the molecular weight increased to 310.It seemed that the N1Cl₂-KCl-LiCl catalyst mixture in all catalyst/coal ratios was more efficient in molten phase than it was used as a solid mixture.     

STRUCTURAL GROUP ANALYSIS OF PRODUCTS FROM TWO-STAGE LIQUEFACTION OF HIGHVALE COAL

ABSTRACT

Products from liquefaction of Highvale Coal (Alberta. subbituminous) in anthracene oil and recycled product, with iron oxide catalyst, were studied using a structural group analysis method. The various functional groups were determined using a combination of proton NMR. carbon-13 NMR. IR. elemental analysis and nitrogen titration analysis. The liquefaction reactions in anthracene oil and in recycled product oil were compared on the basis of three solvent quality Indices and the predominant structural groups in the resulting liquids. The results show that major structural changes occur at both stages of liquefaction. Processing in anthracene oil showed much greater structural changes than liquefaction in the recycled product. The structural profiles Indicated a reduction in aromatic structures and a dramatic increase in aliphatic and naphthenic structures during processing in anthracene oil. These changes were attributed to the hydrogenation of aromatic structures and the dissolution of aliphatic and naphthenic compounds. Liquefaction in recycled product showed less significant changes in structural composition but resulted in a better quality product in terms of the amount of distillable oils, transferable protons and hydrogen to carbon ratio. This improvement was attributed to the improved availability of donatable hydrogen in the recycled product.