Effect of temperature, solvent/coal ratio and beneficiation on conversion and product distribution from direct coal liquefaction

• Beneficiated coal fractions obtained by column flotation.
• Direct coal liquefaction of original and beneficiated fractions in a batch reactor.
• Yield and product distribution depend on temperature, solvent/coal ratio and type of coal.
• Conversion from beneficiated coal lower than from original coal.

In this paper, the effect of temperature, solvent/coal ratio (S/C) and coal beneficiation (concentrates in organic matter) on the conversion and product distribution from Direct Coal Liquefaction (DCL) is studied. Coal from Cerrejón, colliery in Colombia, and a non-hydrogenated anthracene oil solvent were used. Experiments were carried out in a reactor batch of 500 ml, temperatures at 380, 400 and 420 °C for 30 min and 800 psig (5.5 MPa) hydrogen pressure, using three S/C ratios: 2/1, 3/1 and 4/1. Coal beneficiation was conducted in a continuous flotation column. Results showed that the S/C ratio has a positive effect on the conversion and oil content, whereas temperature has a negative effect for liquefactions of original and beneficiated coal. Moreover, liquefactions showed increasing production of gas when temperature increases while the S/C ratio decreases, independently of the type of coal used. There is a negative effect using concentrate’s coal in organic material. A marked reduction on conversion and the amount of oil is produced due to some minerals which act as catalysts – such as illite, montmorillonite, and clay minerals – were removed during the flotation process.