An initial reaction pathway analysis of direct coal liquefaction: Experimental results

Abstract

An experimental stirred tank apparatus was developed to study the initial reaction pathways and mechanisms of both gas-liquid and gas-liquid-solid systems. This pulse-injection flow reactor exploits the vessel's residence time distribution to obtain a series of isothermal samples of well defined residence times. The reactor design allowed for quick and efficient procurement of optimally spaced and sized samples. Results from the use of the reactor system to probe the pyrolysis kinetics of an 11-component coal model compound mixture and the liquefaction of several coal samples in tetralin are reported. This permitted study of the competing effects of reaction and extraction during coal liquefaction. In the 11-component mixture, dibenzyl ether conversion was accelerated by the presence of radical initiators as its overall disappearance rate constant was k/s −1 = 2.1 × 10 −3. The experiments with coal and coal-derived material revealed that extraction produced single-ring aromatics and short side chains while degradation of the coal's rigid phase produced condensed aromatic species and α-protons.