Review

Direct coal liquefaction can be an alternative source of liquid fuels. The aim was to maximize the liquid product yield for DCL tests without hydrogen pressure using tetralin as solvent. Experiments were carried out in an autoclave (300 ml) in nitrogen (P = 0 bar). Tests were performed at 300, 350, 400 and 450 °C (1 h) using 1:1 or 0.4:1 of Brown Coal:Tetralin weight ratio. Then, solids, gases and liquids were sampled. The liquid product was analysed by elemental analysis, TGA, solubility in heptane and simulated distillation, the gas by GC-FID/TCD and the solids by solubility in n-heptane, xylene and trichloroethylene. The increment of temperature from 300 °C to 400 °C supposed an increment in the total amount of direct liquids products soluble in n-heptane. The maximum yield to n-heptane soluble products was found for the test carried out at 400 °C (1:1 weight ratio).