Synergistic Effect of Co-pyrolysis of Low-Grade Coal and Heavy Oil

This study explores the co-pyrolysis of low-rank coal with heavy oil to address challenges in processing high-viscosity crude oil.Various coal-to-oil ratios were tested to evaluate yield and thermal behavior.Adding 20-80% heavy oil increased tar and gas yields by 50.69% and 10.39%, respectively, while reducing semi-coke yield by 61.08%.The presence of heavy oil lowered peak decomposition temperatures in DTG spectra and intensified corresponding peaks, indicating enhanced reactivity.A positive synergistic effect was observed at 80% oil addition, while 20-60% additions showed a negative effect.This synergistic effect was confirmed by TG-DTG-DSC analysis, revealing maximum weight loss and loss rates at 80% oil.Tar composition shifted, with a 20.64% rise in aromatic hydrocarbons and decreases in alkanes, olefins, and phenols by 9.76%, 2.44%, and 2.71%, respectively.Gas analysis showed increased H, CH, and CnHm, with lower CO and CO levels, likely due to hydrogen from oil reacting with coal's oxygen groups via hydrogenolysis.These findings suggest that co-pyrolysis with heavy oil enhances product yield and quality, offering a promising route for upgrading heavy crude oil.