Calorimetric study of quinoline interaction with o-phenylphenol and coal-derived asphaltenes

✍ Scribed by Krishna C. Tewari; Laurine G. Galya; Kenneth M. Egan; Norman C. Li

• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 540 KB
• Volume: 57
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(78)90124-2

✦ Synopsis

A calorimetric method is presented for the simultaneous evaluation of equilibrium constant, K, and molar enthalpy, AHO, for 1 :I 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 dm3 mol-I; whereas there is large variation in the AH0 values (Qu-A, -16.92 + 0.21 kJ mol-I; Qu-AA, -14.7450.04 kJ mol-'; Qu-BA, -11.76?0.04 kJmol_'). 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 hydrogenbond acceptors. Since asphaltenes are really mixtures, we have taken a pure compound, o-phenylphenol (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 (dm3 mol-'1: 10.4 (in C!+1,6.2 (in CCl4); AHD (kJ mol-'1: -31.40 (in CS21, -27.80 (in CCl4). 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 ITinteractions in the total enthalpy change for the OPP-QU system is estimated to be 3:l.