Effect of solvent swelling on liquefaction of Xinglong coal at less severe conditions

Xinglong coal, a sub-bituminous coal, was swollen with pyridine or tetrahydrofuran followed by liquefaction in a 70-ml autoclave apparatus. The experiments were carried out to investigate the effects of temperature, solvent, atmosphere and catalyst on the liquefaction of solvent-swollen coal and untreated coal. The results indicate that the conversion of coal could be effectively improved in the temperature range of 320-420 degreesC by swelling pretreatment. Molecular hydrogen shows no contribution to coal conversion during the liquefaction of pyridine-swollen coal in the absence of a catalyst and in the presence of hydrogen donor solvent such as tetralin. With the addition of a catalyst, the liquefaction conversion of pyridine-swollen coal is higher in H-2 than that in N-2. The swelling pretreatment of coal can improve the liquefaction yields, weaken the dependence of the process on the presence of molecular hydrogen and the hydrogen donation ability of the solvent, and increase the conversion of coal liquefaction. (C) 2000 Elsevier Science B.V. All rights reserved.