STUDY OF THE EFFECT OF AQUEOUS ALKALI PRETREATMENT ON COAL LIQUEFACTION.

Experiments were performed to investigate the effects of aqueous sodium hydroxide pretreatment upon coal liquefaction in a combined process of pretreatment and liquefaction. The influence of leaching time and temperature, and the concentration of sodium hydroxide upon sulfur removal and liquefaction yield was examined. The progression of dissolution for unpretreated coal, pretreated coal and washed pretreated coal at various liquefaction times was also studied. Hydrothermal treatment of coal using distilled water was tested as a special case of alkali treatment. It is observed that sodium hydroxide treatment increases the total sulfur removal whereas it slightly decreases the liquefaction yield in the combined process.