Hydrogen bonding in asphaltenes and coal. Progress report, April 1, 1978--June 30, 1978

Abstract

A direct calorimetric method has been used to determine simultaneously the molar enthalpy, ..delta..H/sup 0/, and equilibrium constant, K, for quinoline (QU) interaction with coal-derived asphaltenes (A), acid/neutral (AA) and base (BA) components of A, silylated asphaltenes (A(TMS)) and heavy oil (HO) fractions in solvent C/sub 6/H/sub 6/. Solvent fractionated A and HO fractions were from three centrifuged liquid product (CLP) samples prepared in the 450 kg (/sup 1///sub 2/ ton) per-day Process Development Unit at Pittsburgh Energy Research Center, at different process conditions from the same feed coal, Kentucky hvAb. For a given system, Qu-A (AA or BA), Qu-HO, the almost constant value of K and linear variation of ..delta..H/sup 0/ with the phenolic oxygen content of coal liquid fractions, have been attributed to the dominance of hydrogen-bonding effects, involving phenolic OH, over other types of molecular interactions in solution. In Qu-A(TMS) system, -..delta..H/sup 0/ values increase with decrease in molecular weight of A(TMS), while -..delta..S/sup 0/ values increase with increase in aromaticity of A fraction. The degree of complexation, in absence of OH groups, is much smaller than Qu-A system and largely depends upon some unusual entropy effects.