Calorimetric study of quinoline interaction with o-phenylphenol and coal-derived asphaltenes
A calorimetric method is presented for the simultaneous evaluation of equilibrium constant, K, and molar enthalpy, ΔH o , for 1:1 adduct formation of quinoline (Qu) with coal-derived asphaltenes in solvent benzene. Asphaltene ( A), together with its acid/neutral ( AA), and base ( BA) fractions used...
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Published in | Fuel (Guildford) Vol. 57; no. 4; pp. 245 - 249 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier Ltd
1978
|
Online Access | Get full text |
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Summary: | A calorimetric method is presented for the simultaneous evaluation of equilibrium constant,
K, and molar enthalpy,
ΔH
o
, for 1:1 adduct formation of quinoline (Qu) with coal-derived asphaltenes in solvent benzene. Asphaltene (
A), together with its acid/neutral (
AA), and base (
BA) fractions used in this study were isolated from a centrifuged liquid product (
CLP) sample prepared from Kentucky hvAb coal at 27.6 MPa hydrogen pressure and 723 K, with reactor charged with glass pellets. The computed
K values for the interaction of Qu and
A,
AA, and
BA are, within experimental error, the same, 18–19 dm
3 mol
−1; whereas there is large variation in the
ΔH
o
values (Qu-
A, −16.92 ± 0.21 kJ mol
−1; Qu-
AA, −14.74 ± 0.04 kJ mol
−1; Qu-
BA, −11.76 ± 0.04 kJ mol
−1). For Qu-
A and Qu-
AA systems, hydrogen-bonding occurs between the aromatic phenols (present in
A and
AA) and quinoline, which is a strong hydrogen-bond acceptor, in addition to other molecular interactions. The hydrogen-bonding interaction in the Qu-
BA system is lacking because both Qu and
BA are hydrogen-bond acceptors. Since asphaltenes are really mixtures, we have taken a pure compound,
o-phenyl-phenol (OPP), and obtained thermodynamic parameters for its interaction with quinoline (Qu). OPP was chosen to represent the aromatic phenols found in coal liquefaction products. Results obtained are:
K (dm
3 mol
−1): 10.4 (in CS
2), 6.2 (in CCl
4);
ΔH
o
(kJ mol
−1): −31.40 (
in
CS
2) −27.80 (
in
CCl
4). The solvent effect is apparent. By using
o-phenylanisole as a model non-hydrogen-bonding donor (Dietz Blaha, Li
J. Chem. Thermodynamics, 1977,
9, 783), the relative contribution of H-bond to π-interactions in the total enthalpy change for the OPP—Qu system is estimated to be 3:1. |
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ISSN: | 0016-2361 1873-7153 |
DOI: | 10.1016/0016-2361(78)90124-2 |