Synergistic effects on thermochemical behaviors of co-pyrolysis between bio-oil distillation residue and bituminous coal

Co-pyrolysis characteristics of bio-oil distillation residue and bituminous coal were investigated through thermogravimetric analysis coupled with Fourier transform infrared spectrophotometer (TGA-FTIR). The addition of bituminous coal changed the behaviors and kinetics of pyrolysis reaction. With temperature increasing, synergistic effects rapidly increased at relatively low temperatures, and then kept a decreasing tendency with different rates until a relatively steady state. The results of the quantitative analysis of chemical functional group by the peak area of infrared spectroscopy indicated that the addition of bituminous coal had a positive effect on the production of CO2 and CO, and a negative effect on the functional groups containing C-H, C=C and C-O bond. The co-pyrolysis mechanism and kinetics parameters were calculated by the Coats-Redfern and Flynn-Wall-Ozawa method, suggesting that the activation energy and the reaction order of co-pyrolysis increased with mixing ratio increasing in main step. The lowest activation energy (73.17 kJ/mol by Coast-Redfern method and 71.46 kJ/mol by Flynn-Wall-Ozawa method) was obtained by blending 20 wt% bituminous coal.