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

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.     

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.     

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.     

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.     

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     

LIQUEFACTION AND THE CHARACTERIZATION OF COAL DERIVED LIQUIDS OF MENGEN LIGNITE

ABSTRACT

The liquefaction characteristics of Mengen lignite has been investigated in the presence of cobalt-molybdenum on alumina catalyst in a 1 lt batch autoclave system with anthracene oil used as solvent. The experiments were carried out in the range of 15–60 atm for initial hydrogen pressure, 360–440°C for reaction temperature, 1–5 for solvent to coal ratio and 0–20% of coal for catalyst loading which were chosen as process variables. Coal particle size and reaction time were kept constant as below 200 mesh and 30 minutes respectively, (Erdem 1987)

The product was analyzed in terms of total conversion, liquid yield and liquid product distribution determined as preasphaltenes, asphaltenes and oils. The oil fraction was further separated by column chromatography while the asphaltenes were separated into basic and acid/neutral fractions. The preasphaltenes were divided into two fractions as carbene (CS₂ solubles) and carboid (CS₂ insolubles). (Inanç 1989)

The oil yield is mostly affected by the catalyst loading which shows to a certain extent that the conversion of asphaltenes to oils is a catalytic step. The selected process variables showed a positive trend with respect to the yield of hexane eluted oil which is the desired product of liquefaction.     

STEAM GASIFICATION OF BALMER COAL IN THE PRESENCE OF LIGNITE ASH

ABSTRACT

Steam gasification of blends prepared from Balraer coal and the ash from combustion of Onakawana lignite was performed in a fixed bed reactor. The blends were prepared by co-slurrying followed by drying. In the presence of 20 wt % ash the gasification rate doubled at 830° and 930°C. Direct blending of coal and lignite resulted In an overall increase in carbon conversion at 830°C but had no effect at 930°C.     

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.     

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

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     

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.     

COPROCESSING OF COAL WITH HEAVY PETROLEUM CRUDES AND RESIDUA

ABSTRACT

This work investigates the coprocessing of coal in six different heavy petroleum crudes and residua. Coprocessing reactions of coal and the petroleum solvents are performed under three sets of constant reaction conditions, yielding informative comparative data for processing applications. Definitive comparisons of coal reactivity and solvolysis in the petroleum solvents have been obtained using solvent fractionation which provides a measure of the degree of upgrading achieved by the liquefied coal. Regressive reactions and low coal conversions are observed in coprocessing reactions in N₂ at 400^°C. Higher conversions and a reduction in regressive reactions are observed in H₂ at 400^°C. Catalytic hydrotreatment and higher temperature, 425^°C, result in increased coal conversion and a net production of pentane soluble materials. The amount of product fractions obtained from the upgrading of the coal alone is calculated. The effect of reaction temperature using different solvents and reaction conditions on the product slate is also examined.     

LIQUEFACTION OF ELBI˙STAN AND YATAĞAN LIGNITES I N CARBON MONOXIDE/HYDROGEN GAS MIXTURES

Abstract

Thc effects of experimental parameters on the liquefaction yields of Elbistan and Yatagan lignites vcre investigated by using different solvents, guses and catalysts.

In hydroliquefaction of Elbistan lignite with anthracene and creosote oils, higher oil yields were obtained with anthracene oil. Based on this result, anthracene oil was chosen as solvent for further work done with Elbistan lignite. First the effect of moisture in lignite samples vas observed with synthesis gas as medium gas: then, the effect of carbon monoxide/ hydrogen ratio in liquefaction gas mixture was determined using moist lignite samples. The highest oil yield was obtained with moist lignite sample in 3CO/IH₂gas mixture and it was 57.3 % (daf).

The hydroliquefaction oil yields of Yatagan lignite obtained with creosote oil were higher than those obtained in anthracene ail. On Further work done with Yatagan lignite, creosote oil was chosen as solvent. First, the effects of CoMo and red mud catalysts, then in catalyzed medium, the effects of moisture in lignite samples and at last, using moist lignite samples and red mud catalyst. the effects o f carbon monaxide/hydrogen in synthesis gas medium and also, the increase in the oil yield a s an effect of catalyst presence, increased further: the 3CO/lH, ratio in gas medium was suitable for obtaining higher oil yields; and also for obtaining high oil yields, 440°c could be taken a s the most suitable temperature value and the pressure should be increased a s much as technical and economical conditions permit.     

CHARACTERIZATION OF COAL CHARS FROM A FLASH PYROLYSIS PROCESS BY CROSS POLARIZATION/MAGIC ANGLE SPINNING 13C NMR

ABSTRACT

Chars from the Illinois Springfield (No. 5) Coal are prepared by flash pyrolysis at progressively higher charring temperatures. The results of a study of these chars by ¹³C NMR with CP/MAS indicate that the initial stage of heating (300^°C) produces a char with aromatic carbon fraction (f_ar) of 68%, and successive heating gives chars with f_ar of 70% (400^°C), 73% (500^°C), 89% (600^°C), 95% (700^°C), and 96% (800^°C). However, the actual amount of aromatic and aliphatic carbon in the char can be calculated by using the NMR measurements, the organic carbon content of the char, and the weight of the char. The calculated values show that the amount of aromatic carbon in char remains relatively constant at each temperature, but the amount of aliphatic carbon in char is reduced during higher temperature charring. At 600^°C, both a large reduction of the aliphatic carbon content and a maximum weight loss occur. Evidently, the aliphatic-bond carbon in coal is the principal source of volatiles derived from coal. The apparent increase in aromaticity (f_ar) of the char heated to progressively higher temperatures is due to the loss of aliphatic-bond moieties and reduction in volume of materials.     

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).     

THERMAL ANALYSIS OF DIFFERENT FOSSIL FUELS

ABSTRACT

In this study DTA and TGA were applied to some fossil fuels. Peat, lignite, bituminous coal, anthracite, oil shale and asphaltite were heated at a constant 15 °C/min up to 1000 °C under nitrogen atmosphere. The DTG curves of the samples were derived using the TG curves. The results are compared and discussed.     

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.     

KINETICS OF THERMAL LIQUEFACTION OF SEYITÖMER LIGNITE

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).     

VARIATION IN THE CHEMICAL NATURE OF ASPHALTENES WITH THE PROCESS,THE COAL AND THE REACTION CONDITIONS

ABSTRACT

Average structure data for twelve asphaltenes are reported, based on ¹³C- and H- n.m.r. spectroscopy combined with elemental, molecular weight and functional group analyses. The asphaltenes were from supercritical gas extraction, flash pyrolysis and hydrogenation of a brown and a bituminous coal. The effect of the reaction temperature and, for hydrogenation, the catalyst and solvent on the nature of the asphaltene produced was studied. The asphaltene obtained from supercritical gas extraction of the brown coal at 350°C was the least aromatic (f_a = 0.44) with the highest H/C atomic ratio (1.16) and probably consists mainly of single ring aromatlcs with about half of the aromatic sites substituted. A significant proportion of the carbon in this asphaltene is in long alkyl chains and the hydroxyl content is high. Whereas, the asphaltenes produced by hydrogenatlon of the bituminous coal at 450°C were far more aromatic with more highly condensed but less substituted aromatic ring systems and few, if any, long alkyl chains, together with a lower hydroxyl content. The asphaltenes obtained from the brown coal are less aromatic with less condensed aromatic ring systems but a higher degree of aromatic substitution than those produced from the bituminous coal under the same conditions. The asphaltenes formed at 450°C had lower H/C atomic ratios, molecular weights and degree of aromatic substitution, but higher aromaticities Ohan those produced at 35O°C or 400°C under like processing conditions. The asphaltene produced in the presence of both stannous chloride catalyst and tetralin was less aromatic than when either of these species was absent.     

SEPARATION OF MACERALS FROM SUBBITUMINOUS COALS AND THEIR RESPONSE TO LIQUEFACTION

ABSTRACT

Separation of macerals from three Alberta subbituminous coals was investigated using float-and-sink method with dense liquids followed by the density gradient technique proposed by Dyrkacz and co-workers at Argonne National Laboratory, U.S.A. Resolutions of 90 percent or greater purity were obtained in some fractions in quantities sufficient to study their response to liquefaction. The ease of liquefaction of macerals isolated from subbituminous coals was, in descending order, liptinite, vitrinite, inertinite. Liquefaction of inertinite occurred at somewhat higher temperatures compared to that of vitrinite macerals which initiated between 350^° and 400^°C.

Analysis of the chemical makeup of macerals from a subbituminous coal indicated that liptinite was relatively rich in hydrogen, whereas vitrinite and inertinite were relatively rich in oxygen and carbon respectively. The average densities were 1.285, 1.345 and 1.458 g/cc for liptinite, vitrinite, and inertinite respectively. X-ray diffraction and NMR spectra of the three macerals were also investigated which will be the subject of a future detailed report.