A coal constituent based kinetic model for direct coal liquefaction

In order to obtain chemically meaningful and extendable kinetics for direct coal liquefaction (DCL) the experimental coal conversion ( X C ) and oil yield ( Y O ) are correlated with coal constituents and the conditions. The coal is assumed to have three constituents mimicking its maceral constituents liptinite, vitrinite and inertinite. The quantities of them are estimated based on the TG curve of coal, and correlated with the X C and Y O by non-linear regression. For Naomaohu (NMH) coal that is dominant with the vitrinite and Shangwan (SW) coal that has similar contents of vitrinite and inertinite, the three-constituent kinetics model is significantly better than that of traditional single-component kinetics model that requires the regression-determined maximum conversion X C,M and maximum oil yield Y O,M . The k 1 for the vitrinite-like component a 1 is always much larger than k 2 for the inertinite-like component a 2, and k 1 usually shows a better relationship with 1/T than k 2 . The E a of NMH for X C and Y O are close to each other, suggesting a high content of weak bonds in the structure; whereas the E a of SW for Y O is significantly larger than that of X C , suggesting that many oil originates from the secondary reaction rather than the primary covalent bond cleavage.