Investigation of the (catalytic) co-pyrolysis of Shendong coal and coal tar based on rapid pyrolysis and ANN modelling

The catalytic co-pyrolysis of coal and hydrogen-rich substances is an effective way to improve the yield and quality of coal tar. In this paper, the co-pyrolysis experiments of Shendong low rank coal (SD) and low temperature coal tar (HCT) catalyzed by hematite, chalcopyrite, nickel laterite, and molybdenite were carried out respectively. The catalytic co-pyrolysis characteristics and product distribution of coal-tar slurry with different coal-tar ratios were investigated by the thermogravimetric analyzer (TGA), pyrolysis-gas chromatography/mass spectrometer (Py-GC/MS), and fixed bed rapid pyrolysis reactor (FBR). In addition, the response surface design method and artificial neural network (ANN) were introduced to optimize catalyst ratios. The analysis results show that the experimental value of the maximum weight loss rate in the high temperature pyrolysis stage with a coal-tar ratio of 5: 5 is greater than the estimated value. Besides, the coal-tar co-pyrolysis has a synergistic effect, which strongly reduces the apparent activation energy of the pyrolysis process. The addition of HCT promotes the generation of oxygen-containing compounds and aromatics. The presence of natural minerals promotes the formation of light tar, especially mono-aromatics, aliphatics, and phenol in the pyrolysis tar. After optimizing and verifying the catalyst ratio by ANN, the pyrolysis tar yield, light component content, and light tar yield are 50.49 wt%, 46.14%, and 21.14 wt%, respectively.

Automated summary

The catalytic co-pyrolysis of coal and hydrogen-rich substances can improve the yield and quality of coal tar. This study investigated the effects of hematite, chalcopyrite, nickel laterite, and molybdenite catalysts on the product distribution of coal-tar slurry. The addition of catalysts reduced the apparent activation energy of the pyrolysis process and promoted the generation of oxygen-containing compounds and aromatics. The presence of natural minerals enhanced the formation of light tar.