Study of Co-liquefaction Process of Chinese Lignite Coals and Lignin from Black Liquor

Co-liquefaction of Shengli lignite and lignin came from black liquor of papermaking Industry and was studied in the presence of hydrogen-donor solvent, tetralin. The experiments were carried out in a 250ml micro-autoclave to investigate the effects of reaction temperature, time, pressure of H-2, and lignite/lignin ratios on the conversion, correspondingly, liquid, and gas yield, asphaltene and preasphaltene yields and hydrogen consumption also being measured. The results showed, coal-lignin co-processing produces the higher oil yield with the lower hydrogen consumption and lower gas yield compared with the liquefaction only by Shengli lignite. The addition of lignin to coal can modify the liquefaction reaction and selectively enhance the liquid yield. Under the conditions of the initial hydrogen pressure of 9Mpa and reaction time of 60min at 410 C, tetralin as hydrogen-donor solvent, and lignite/lignin ratio at 9:1, the conversion rate of feedstock can reach as 92.12% with oil yield 54.3%. The conversion rate and oil yield achieved the maximum at the 9:1 ratio of Shenli coal/lignin and then decreased as the ratio of the Shengli coal and lignin augmented, but asphaltene(AS)/preasphaltene(PAS)yield had been increasing. The effects of the reaction temperature, time and the pressure of hydrogen on the oil yield are discussed on the base of asphaltene and preasphaltene yields.