INVESTIGATIONS OF SIMULTANEOUS COAL AND LIGNIN LIQUEFACTION - KINETIC-STUDIES

Liquefaction of mixtures of an Illinois bituminous coal and a caustic lignin was studied. Reactions were conducted at an initial hydrogen pressure of 1.1 MPa and at a temperature of 375-degrees-C, in tetralin. The liquid product from the coal-lignin mixture contains a lower fraction of the undesirable benzene insolubles than the product for coal alone. Size-exclusion chromatography studies indicate that, with the coal-lignin mixture, the weight-averaged molecular weight for the overall liquid product is lower than the molecular weight obtained by reacting coal or lignin alone. The experimental data also show that a 22% enhancement in coal conversion results due to the addition of lignin. A mathematical model that describes the reaction chemistry has been developed and analyzed. The influence of recycling of the liquid product was also studied. Preliminary experiments indicate that the overall coal depolymerization yields decrease, albeit gradually.