Effects of in-situ mineral matter and a nickel — molybdenum catalyst on hydrogenation of Liddell coal

Rottendorf, H; Wilson, Michael

doi:10.1016/0016-2361(80)90162-3

Cited by 36 publications

(7 citation statements)

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“…In coal liquefaction, the role of catalyst is attributed variously as promoting the rehydrogenation of donor solvent using gasphase hydrogen (Guin et al, 1978;Rottendorf and Wilson, 1980) or capping of reactive fragments produced from thermal cracking of coal using gas-phase hydrogen (Cassidy et al, 1982;Cochran et al, 1982;Moritomi et al, 1983) or promotion of coal-tetralin reactions (Tsai and Weller, 1979). Recently Brooks et al (1983), while examining the effect of pyrite catalysts using a Pittsburg No.…”

Section: Methodsmentioning

confidence: 99%

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Modeling of coal liquefaction kinetics based on reactions in continuous mixtures. Part II: Comparison with experiments on catalyzed and uncatalyzed liquefaction of coals of different rank

Prasad¹,

Agnew²,

Sridhar³

1986

AIChE Journal

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Experimental kinetic data for three Australian coals are compared with predictions from the mathematical model developed in Part I. For these coals, as well as data reported for North American coals, the model is found to show good agreement, using the characteristic molecular weight as the only parameter. The effects of reaction time and temperature are coupled via a severity index that arises in the model as a dimensionless reaction time. The model is also shown to be applicable when catalysts are present. The product distribution for a particular coal seems to be a function only of the conversion even in the presence of catalysts, as long as the chemical reaction controls the rate of liquefaction. SCOPEConventional coal liquefaction kinetic modeling is based on the grouping together of products into several "lumps," usually determined by the solubility properties of the various species present. The reaction networks for such a lumped-product system depend clearly on the particular coal and it is not possible to generalize such models. In Part I, a model based on the concept of reactions in a continuous mixture was proposed and a methodology of applying such a model was developed.In this paper, the product distributions obtained upon liquefaction of three Australian coals-a low-rank Victorian brown coal and two subbituminous coals-are examined and compared with model predictions using the model developed in Part I and the lumping functions proposed therein. The kinetic data were obtained from two different types of reactors, a tubular flow reactor and a batch microautoclave reactor. All experiments were conducted under conditions where there was excess availability of hydrogen from donor solvent (tetralin). In addition, other reported kinetic data for North American coals were examined. The effect of catalyst addition (mostly iron-based), is also examined and the applicability of the model is evaluated. CONCLUSIONS AND SIGNIFICANCEThe model proposed in Part I is found adequate in predicting the product distribution for all coals examined. The only parameter varied between different coals is the characteristic molecular weight for coal.The molecular weight for coal broadly depends upon the rank, and increases as the rank increases.The model provides a basis for coupling the effects of reaction time and temperature using the concept of severity index. The implication for liquefaction of coal is that there is no optimum temperature for maximizing Correspondence concerning this paper should be addressed to T. Sridhar. the yield of a particular product as long as the solvent is capable of supplying all the hydrogen requirements. J . 9. Agnew is presently at the Department of Chemical Engineering, University of Adelaide, Adelaide, 5001. Australia. 1288August 1986 Vol. 32, No. 8 AIChE JournalThe product distribution is uniquely determined by reaction severity. This implies that the activation energy is similar for all reactions in the network. The first-order rate constant for the formation of tetrahydrofuran (THF) s...

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Section: Methodsmentioning

confidence: 99%

“…Effect of catalyst loading on product yield for Liddell coal Rottendorf and Wilson (1980). the constants (Ki's) are related to the molecular weight (M,) Arrhenius plots of first-order rate constant (a) for coal dissolution.…”

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Modeling of coal liquefaction kinetics based on reactions in continuous mixtures. Part II: Comparison with experiments on catalyzed and uncatalyzed liquefaction of coals of different rank

Prasad¹,

Agnew²,

Sridhar³

1986

AIChE Journal

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“…The autoclave (a Parr rocking or Autoclave Engineer's stirring) was charged with coal, tetralin, gas (hydrogen, nitrogen, or deuterium-hydrogen mixture), and heated at reaction temperature for the required time. Sometimes a nickel molybdenum catalyst (Cyanamid HDS-3A) (Rottendorf and Wilson, 1980) was employed to assist hydrogenation.…”

Section: Methodsmentioning

confidence: 99%

“…Bearing in mind these measurements were made without MASS, the results are identical with those obtained in our present study of uncatalyzed reactions. Thus, although conversion can be slightly higher in catalyzed reactions (Rottendorf and Wilson, 1980; Wilson et al, 1982) , catalyst has little or no effect on the aromaticity of the residues.…”

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Changes in aromaticity during coal liquefaction

Wilson¹,

Pugmire²,

Vassallo³

et al. 1982

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

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any light onto this controversy, so steps B and C have been listed separately.The oberved order of reaction with respect to H+ concentration is empirical in this work, since, according to the mechanism, the order should in fact be unity. However, the evidence of acid-catalyzed aldol condensation of MEK precludes exact first-order acid dependence.Other Results. The findings of Neish et al. (1945) cannot be refuted on the basis of this work. The Neish system contained a very strong acid with no effective water concentration, so a different mechanism is conceivable. Neish also reported the formation of the cyclic ketal, 2ethyl-2,4,5-trimethyl dioxolane, by the condensation of 1 mol each of 2,3-butanediol and MEK. This compound was not detected in our work, presumably because the equilibrium lies in favor of 2,3-butanediol and MEK in aqueous solution (see Fife et al., 1967Fife et al., , 1970Fife et al., , 1971. ConclusionsAqueous 2,3-butanediol was shown to react in a pseudo-first-order reaction in the presence of sulfuric acid to form methyl ethyl ketone. The reaction could be described by a pinacol rearrangement mechanism and had an activation energy of 36 kcal/mol. An empirical order of reaction with respect to H+ concentration of 1.53 was determined. MEK yields exceeding 90 mol % could be consistently obtained, but evidence of acid-catalyzed aldol condensation was noted.The pseudo-first-order reaction incorporated the temperature, acid concentration, and initial reactant concentration, and predicted, a priori, the reaction time course for both MEK and 2,3-butanediol.Dehydration of 2,3-butanediol to MEK in fermentation broths is feasible, and the current model can be used as the first step in the development of a more complete model which is directly applicable to 2,3-butanediol fermentation broths.

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“…Detailed studies have been carried out to understand the mechanism of coal particle dissolution (Guin et al, 1976; Wen, *Department of' Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania I526 1. 1979;Han et al, 1978;Oele et al, 1951;Plett et al, 1977) and the roles of the donor solvent (Gliem, 1976;Kang et al, 1976;Neavel, 1976), molecular hydrogen (Vernon, 1980) and inorganic mineral matter (Gangwer and Prasad, 1979;Given et al, 1975;Gray, 1978;Guin et al, 1978Guin et al, , 1979aJackson et al, 1979;Mukherjee and Choudhary, 1976;Rottendorf and Wilson, 1980) in the coal liquefaction process. The mechanism of the liquefaction process has also been studied by many investigators (Brunson, 1979;Cronauer et al, 1978;Curran et al, 1967;Hill et al, 1966;Libenberg and Portgieter, 1973;Oele et al, 1951;Petrakis and Grandy, 1980;Ruether, 1977;Vernon, 1980;Wiser, 1968Wiser, , 1971Gun et al, 1979).…”

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Liquefaction of coal by SRC‐II process: Part I: A new kinetic model

Singh¹,

Shah

Carr³

et al. 1982

Can J Chem Eng

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The kinetic experiments were carried out in a continuous stirred tank reactor. Practically important ranges of SRC‐II reactor temperature (444–466°C), pressure (10.4–20.8 MPa), nominal slurry residence time (0.54–1.62 h), coal concentration in the feed slurry (25–35 wt%), and inorganic mineral matter concentration (4.75–13.43 wt%) were covered in a total of 43 experimental runs. In each of the experimental runs, the feed slurry was formulated by using vacuum tower bottoms from SRC‐II pilot plants using the same feed coal (Powhatan No. 5), to obtain feed compositions similar to those obtained in SRC‐II pilot‐plant recycle operation. The kinetic model considers the overall conversion to be achieved in two stages. The first stage is the instantaneous dissolution of coal and in the rate controlled second stage all the reactive organic components in the liquid phase are initially assumed to react, each yielding components lighter than itself. The distribution of products in each reaction stage is considered to be independent of the operating conditions. The best rate controlled (second stage) reaction scheme and values of the unknown parameters are obtained by minimizing the overall difference (i.e. for all the components over all the runs) between the measured and model predicted mass fractions of the various components in the reactor. This analysis identifies the reaction of solvent refined coal (pyridine soluble organic matter boiling above 482°C) to be the only significant reaction in the second stage and its rate is determined to be ‐rSRC = 1.567 × 105 exp (‐79.16/RT) · p0.28 H 2 · XASH, kg/L h. Overall error in this analysis yielding the reaction scheme, rSRC and values of product distribution coefficients for both the reaction stages is less than 8% absolute i.e. ±4%.

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Effects of in-situ mineral matter and a nickel — molybdenum catalyst on hydrogenation of Liddell coal

Cited by 36 publications

References 5 publications

Modeling of coal liquefaction kinetics based on reactions in continuous mixtures. Part II: Comparison with experiments on catalyzed and uncatalyzed liquefaction of coals of different rank

Modeling of coal liquefaction kinetics based on reactions in continuous mixtures. Part II: Comparison with experiments on catalyzed and uncatalyzed liquefaction of coals of different rank

Changes in aromaticity during coal liquefaction

Liquefaction of coal by SRC‐II process: Part I: A new kinetic model

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