Thermochemical behavior and char morphology analysis of blended bituminous coal and lignocellulosic biomass model compound co-pyrolysis: Effects of cellulose and carboxymethylcellulose sodium

• Co-pyrolysis characteristic of lignocellulosic biomass major components and bituminous coal was evaluated.
• CE and CMC showed opposite synergistic effects on the char yields during co-pyrolysis.
• Kinetic parameter was calculated by iso-conversional approach (Flynn–Wall–Ozawa).
• Surface morphology of co-pyrolysis char were analyzed based on fractal theory.

Lignocellulosic biomass–coal co-pyrolysis is a promising approach for greenhouse gas reduction. The thermochemical behaviors and product distributions must be understood to optimize the process. This paper examines the effects of lignocellulosic biomass model components (cellulose and carboxymethylcellulose sodium) on the thermal behavior of bituminous coal (BC) using a non-isothermal thermogravimetric analysis. The co-pyrolysis char surface morphology was evaluated using scanning electron microscopy technology (SEM) and a fractal dimension analysis. A positive char yield synergistic effect was observed between BC and CE. CMC exhibited a negative synergistic effect on BC pyrolysis, with char yields being higher than predicted. The additions of CE and CMC decreased the average activation energy of the co-pyrolysis process. A fractal analysis of SEM images provided quantitative information pertaining to the effects of CE and CMC on the co-pyrolysis char surface morphology. The BCCE (BC and CE mixtures) co-pyrolysis char fractal dimensions were less than those of BC and CE chars, indicating that the addition of CE promoted the uniformity degree of the co-pyrolysis char. The BCCMC (BC and CMCE mixtures) co-pyrolysis char fractal dimensions displayed the opposite trend.