Noncatalytic Coal Liquefaction in a Donor Solvent. Rate of Formation of Oil, Asphaltenes, and Preasphaltenes

Shalabi, Mazen A.; Baldwin, R.M.; Bain, Richard L.; Gary, James H.; Golden, J. O.

doi:10.1021/i260071a021

Cited by 72 publications

(33 citation statements)

References 5 publications

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“…Studies using similar reactors have been reported by other groups (Hill et al, 1966;Wiser, 1968;Whitehurst and Mitchell, 1977;Shalabi et al, 0196-432118311222-0478$01 .SO10 1979;Whitehurst et al, 1980). Since conventional batch autoclaves are unsuitable for isothermal experiments, as the time required for the autoclave and its contents to attain reaction temperature can be substantial, the liquefaction behavior of an Australian bituminous coal (Liddell) was investigated with a rapid injection reactor designed specifically for this purpose.…”

Section: Introductionsupporting

confidence: 55%

Isothermal studies of the liquefaction of Liddell coal

Foster¹,

Wilson²,

Weiss³

et al. 1983

Ind. Eng. Chem. Prod. Res. Dev.

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The optimum polymer dosage for 50 wppm oil is three to four times lower than that for 350 wppm oil. ConclusionsBased upon the laboratory jar tests conducted in this study, the following conclusions are drawn.1. Flocculation of the oillwater emulsions studied was enhanced by the use of the slightly cationic polymer, Calgon WT 2575 (20% PDADMA).2. An increase in mixing intensity, above that normally used, enhanced the flocculation rate of the oil/water emulsions studied.3. It was found that prolonged mixing of the oil/water emulsions after initial dispersion of the flocculant provided increased removal of the smaller oil drops. Up to 30 min of prolonged agitation resulted in a continuous decrease in the total oil drop population.4. The optimum polymer dosage did not change noticeably with mixing intensity. However, it did increase with increasing oil concentration for a given mixing intensity. AcknowledgmentThe authors gratefully acknowledge partial support of this work by the member companies of the University of Tulsa Environmental Protection Projects program. NomenclatureG = mean velocity gradient, s-l k = Boltzmann constant, (g cm2/s2)/K K = perikinetic flocculation rate constant, cm3 s K' = orthokinetic flocculation rate constant, s-N o = total number of particles in suspension per cm3 at time No = total number of particles at time t = 0 s, l/cm3 t = time, s T = absolute temperature, K Greek Letters 7 = collision efficiency factor p = fluid viscosity, g/cm-s d = volume of colloidal particles per unit volume of suspension Literature Cited Bernstein, D. F.; Higuchi, W. I.; Ho, N. F. H.The liquefaction of an Australian bituminous coal (Liddell) was studied under isothermal conditions with tetralin as solvent. The influences of reaction temperature (400, 450 "C) and reaction time (0-2 h) on the yields and nature of products were determined. Particular emphasis was placed on short contact times (0-20 min). The initial dissolution reactions were rapid and were associated with considerable reductions of the average molecular weight of the products. The high average molecular weights of the product fractions at very short reaction times (<5 min) have not been observed in studies with conventional autoclaves. 13C NMR (CPIMASS) was used to determine the total aromaticity of the products and residues from coal liquefaction. At 450 O C , significant increases in the aromaticities of the products and residue occurred in the first 2.5 min of reaction and a large proportion of the aliphatic components of the coal was rapidly converted to gas. The amount of aromatic ring hydrogenation at 400 O C was negligible.

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Section: Introductionsupporting

confidence: 55%

Isothermal studies of the liquefaction of Liddell coal

Foster¹,

Wilson²,

Weiss³

et al. 1983

Ind. Eng. Chem. Prod. Res. Dev.

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“…For good design and scale-up of coal liquefaction units it is essential to obtain reliable kinetic data under conditions existing both in preheater and reactor. Most kinetic studies reported in literature haye been carried out at high temperatures (>673 K) and at long residence times (10-60 min) (Cronauer et al, 1978;Shalabi et al, 1979). Studies in short contact time coal liquefaction have shown that coal is thermally fragmented into smaller molecules which are soluble in pyridine (Neavel, 1976;Whitehurst et al, 1977).…”

Section: Introductionmentioning

confidence: 99%

Kinetics of short contact time coal liquefaction. Part I: Effect of operating variables

et al. 1984

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“…Product distribution data for Indiana Paper coal at 375 "C does not show a decrease in preasphaltenes with time. Shalabi et al (1979) found that at lower liquefaction temperatures, preasphaltenes remain the predominant species for much longer times. The effect of temperature on product distribution is indicated in Table IV for a series of 1-h runs performed with Indiana VI1 coal at 375,400, and 425 "C. The fraction of coal converted to maltenes increased with increasing temperature.…”

Section: Resultsmentioning

confidence: 97%

Liquefaction behavior and product distribution for two Indiana coals and their macerals

Semones¹,

Carlin²,

Shi³

et al. 1985

Ind. Eng. Chem. Proc. Des. Dev.

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Vitrinite and exinite macerals were liquefied to gain a better understanding of their role in the liquefaction of whole coals. A minireactor was developed for liquefying small amounts (approximately 1 g) of coal samples; a modified liquid extraction column was also developed for product analysis. Vitrinite-rich whole coals and the vitrinites investigated had comparable liquefaction behavior but the kinetics of exinite liquefaction was substantially slower. At higher temperatures (425 "C), maltene production increased but was accompanied by a decrease in conversion. This suggests that repolymerization of the heavier fractions may occur. write addiiion to exinite samples increased conversions and increased maltene production in the liquid products. Comparison of the conversions of pure macerals and maceral mixtures indicated that there are synergistic effects between the macerals. Other variables investigated include choice of donor solvent, solvent-to-coal ratio, and reactor agitation.In recent years, numerous investigations have been made of the chemical and physical properties of coal and of coal liquefaction products. Much information has been collected describing the petrographic composition of coal (Stach et al., 1975); however, relatively limited information has been reported regarding the liquefaction behavior of pure or relatively pure macerals. Fisher et al. (1942) performed one of the first studies correlating liquefaction behavior with the chemical composition of coal. Vitrinite-rich samples produce high oil content coal liquids. Given et al., (1975a and 1975b) indicated the importance of petrographic composition on liquefaction behavior. Later work (Abdel-Baset et al., 1978) correlated the conversion of 68 whole coals with the concentration of reactive macerals (defined as vitrinite, pseudovitrinite, and sporinite). Considerable evidence exists (Mukherjee and Chowdhury 1965; Guin et ai., 1979a; Lee et al., 1977; Granoff and Thomas, 1977;Guin et al., 1979b), indicating that naturally occurring minerals in the coal can act as liquefaction catalysts. The complex structure and heterogeneity of coal has been a major problem in understanding the coal liquefaction process.Procuring pure maceral samples would be most helpful in studying the effect of petrological composition on coal liquefaction behavior. Sink-float procedures (Dormans et al., 1957;Ergun et al., 1959; Kroger, 1956) have been used in the past to separate macerals from whole coals. In these procedures, the macer& are separated by differences in their densities when the finely ground coal is suspended in a liquid medium such as carbon tetrachloride/toluene. This technique has three disadvantages: (1) it does not account for association or coexistence of individual macerals, maceral groups, or mineral matter in the coal matrix (such associations may affect liquefaction behavior); (2) exposing coal surfaces to liquids results in physical or chemical changes in the macerals; and (3) extensive grinding such as is necessary with these separation t...

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Noncatalytic Coal Liquefaction in a Donor Solvent. Rate of Formation of Oil, Asphaltenes, and Preasphaltenes

Cited by 72 publications

References 5 publications

Isothermal studies of the liquefaction of Liddell coal

Isothermal studies of the liquefaction of Liddell coal

Kinetics of short contact time coal liquefaction. Part I: Effect of operating variables

Liquefaction behavior and product distribution for two Indiana coals and their macerals

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