“…In the initial stages of reaction, it is believed that a large number of free radicals are produced which are then stabilized by hydrogen abstraction from hydrogen-rich portions of coal or solvent (Curran et al, 1966;Collins et al, 1978;Petrakis and Grandy, 1980;Larsen et al, 1981), very little molecular hydrogen is consumed in this stage. This result is exploited in the short contact time two-stage process (Tarrer et al, 1981;Kleinpeter et al, 1979). Previous investigations on short contact time coal liquefaction are summarized in Table 1.…”