Pyrolysis characteristics and kinetics of residue from China Shenhua industrial direct coal liquefaction plant

• Pyrolysis behavior of direct coal liquefaction residue (DCLR) and its four fractions were investigated.
• The inorganic components in DCLR have catalytic effects on both pyrolysis and gasification.
• The pyrolysis activation energy of DCLR obtained from DAEM is in the range of 68.4–142.9 kJ/mol.

The objective of this work is to comprehensively investigate the pyrolysis characteristics of the direct coal liquefaction residue (DCLR) from China Shenhua industrial direct coal liquefaction plant. The pyrolysis experiments were conducted with TGA under four kinds of atmospheres (N2, 10% H2, CO2, and air) and a fixed bed reactor in N2. Two obvious mass loss peaks at 470 °C and 770 °C, are mainly attributed to decomposition of the organic matrix and inorganic compounds in DCLR, respectively. The four fractions extracted from DCLR (hexane soluble fraction (HS), asphaltene fraction (A), preasphaltene (PA), and tetrahydrofuran insoluble (THFIS)) were studied separately by TG-FTIR, and the results show that the interaction among the fractions is unfavorable for the evolution of volatile matter. In addition, the inorganic compounds in DCLR exhibit catalysis behaviors on both pyrolysis under N2 and gasification under CO2. Moreover, the properties of DCLR pyrolysis products obtained from the fixed bed reactor were analyzed by GC–MS, SEM, and FTIR. Finally, a kinetic analysis of DCLR pyrolysis was performed using the distributed activation energy model (DAEM). The activation energy distribution of DCLR follows an approximate Gaussian distribution with a mean activation energy of 87.6 kJ/mol.

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