Synergistic effects from co-pyrolysis of lignocellulosic biomass main component with low-rank coal: Online and offline analysis on products distribution and kinetic characteristics

To comprehensively understanding the synergistic effects from co-pyrolysis of cellulose and low-rank coal, product distribution and kinetic characteristics were investigated based on both online and offline models. Thermogravimetric analysis combined with differential scanning calorimetry (DSC) and tubular furnace combined with online mass spectrometer were applied to investigate the synergistic effects from product distribution under slow and fast co-pyrolysis process, respectively. The model-free method and iso-conversion method were used for analyzing the synergistic interactions of kinetic characteristics. The results indicated that positive synergy from volatile products and kinetic behavior were observed from the slow co-pyrolysis with 50 wt% and 75 wt% of cellulose, with the lowest activation energy of 244.44 kJ.mol(-1) and 164.41 kJ.mol(-1), respectively. Thermal effect analysis from DSC indicated that the endothermic interval of cellulose was corresponding with the synergy interactions. For the fast co-pyrolysis process, both the temperature and the mass ratio of cellulose influenced the synergistic effect. Cellulose inhibited the formation of gaseous products and promoted the formation of tar. A negative synergistic effect was observed from the formation of CH4 and H-2. The activation energy for the generation of CH4 and H-2 from the mixture was higher than that of cellulose or low-rank coal alone. The results could provide some guidance for selecting proper reaction conditions with the optimal synergy during co-pyrolysis process.